EP4648836A1 - Systems, devices, and methods for detecting ventriculoperitoneal shunt failure - Google Patents

Abstract

A ventriculoperitoneal (VP) shunt system comprises a VP shunt device comprising a ventricular catheter, a drainage catheter, a flow control valve fluidly connecting the ventricular catheter to the drainage catheter, and one or more capacitive and/or resistive flow sensors positioned at one or more positions of a fluid flow path comprising the ventricular catheter, the flow control valve, and the drainage catheter, and a computing system communicatively connected to the VP shunt device comprising a processor and a non-transitory computer- readable medium with instructions stored thereon, which when executed by the processor, performs steps comprising a method for detecting VP shunt blockage or failure.

Description

SYSTEMS, DEVICES, AND METHODS FOR DETECTING VENTRICULOPERITONEAL SHUNT FAILURE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. provisional application No. 63/479,398, filed on January 11, 2023, the contents of which are incorporated herein by reference as if set forth in its entirety.

BACKGROUND OF THE INVENTION

[0002] Elevated intracranial pressure (ICP) is associated with a myriad of neurological disorders and can lead to fatal brain herniation. ICP rises in response to excessive accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain. Management of elevated ICP in hospitalized patients often involves the diversion of CSF out of the ventricles and through a device known as an extraventricular drain (EVD), which is effectively a drainage catheter inserted into the lateral and third ventricles. As pressure builds in the ventricles, the catheter offloads excess CSF through the EVD from the ventricles and into a container outside of the body. The amount of fluid drained depends on the ICP, the amount of CSF being produced, and the level (height) of the EVD drainage system in relation to the patient's head. EVDs serve as a temporary means of alleviating elevated ICP. The goal in hospitalized patients with an EVD is to eventually wean the patient off of the EVD as their physiologic ability cycle CSF from the ventricular system of the brain recovers and ICP returns to physiologic levels. [0003] A subset of patients, however, never recover physiologic CSF flow, and require a more permanent device known as a ventriculoperitoneal (VP) shunt to be implanted. A typical VP shunt system comprises 3 main parts: 1) the ventricular catheter; 2) the pressure outlet valve (which is often adjustable); and 3) the distal catheter. The VP shunt system is inserted permanently into the ventricles of the brain, runs under the skin of the scalp and neck, and drains excess CSF into the peritoneal cavity (or other body cavity, such as the pleural cavity or atrium of the heart). Therefore, the patient can be discharged from the hospital with the VP shunt in place and the pressure outlet valve serves to evacuate excessive CSF which builds up in the cerebral ventricular system.

[0004] An estimated 30,000 VP shunts are implanted annually in the United States, including both adult and pediatric patients. Unfortunately, VP shunt failure post-implantation is a significant problem, with 30-40% of shunts failing within the first year and 50% failing within the first two years due to a variety of causes, such as shunt obstruction, valve failure, disconnection, catheter fracture, infection, and displacement, among others, leading to thousands of emergent shunt revisions and a potentially fatal outcome if not promptly addressed [Kumar, Monisha, et al., eds. Neurocritical care management of the neurosurgical patient E-Book. Elsevier Health Sciences, 2017; Ahmadvand, Saba, et al. "Rate and risk factors of early ventriculoperitoneal shunt revision: a five-year retrospective analysis of a referral center." World Neurosurgery 134 (2020): e505-e511]. Numerous mechanisms underlie shunt failure, including shunt obstruction, valve failure, disconnection, catheter fracture, infection, and displacement, among others. However, all of these mechanisms ultimately lead to the same endpoint: arrested CSF flow through the shunt. [0005] Since it is difficult to detect VP shunt failures, there are frequent patient encounters in the emergency department for shunt evaluation and emergent shunt revisions. Numerous devices have been developed to detect shunt failure, but these are limited in their practical use by various shortcomings including power expensive operation precluding battery-powered implantation, non-continuous function, insufficient sensitivity for measuring the slow flow of CSF, disturbance of CSF flow dynamics, MRI incompatible [Bork, Toralf, et al. "Development and in-vitro characterization of an implantable flow sensing transducer for hydrocephalus." Biomedical microdevices 12.4 (2010): 607-618; Soler GJ, et al., A Review of Cerebral Shunts, Current Technologies, and Future Endeavors. Yale J Biol Med. 2018 Sep 21;91(3):313-321. PMID: 30258318; PMCID: PMC6153620; Krishnan SR, et aL, Continuous, noninvasive wireless monitoring of flow of cerebrospinal fluid through shunts in patients with hydrocephalus. NPJ Digit Med. 2020 Mar 6;3:29. doi: 10.1038/s41746-020-0239-l. PMID: 32195364; PMCID: PMC7060317; Pennell T, et al., Noninvasive measurement of cerebrospinal fluid flow using an ultrasonic transit time flow sensor: a preliminary study. J Neurosurg Pediatr. 2016 Mar;17(3):270-7. doi: 10.3171/2015.7.PEDS1577. Epub 2015 Nov 13. PMID: 26565943],

[0006] Patients with shunt failure who do not reach medical attention promptly are at risk of irreversible neurological injury and even death. There is therefore a pressing need for an advanced warning system that can alert the patient and medical care personnel of reduced shunt function and impending VP shunt failure before the onset symptoms occur, thereby avoiding emergency scenarios. Ideally, this system would be fully implantable, would be magnetic resonance image (MRI) compatible, would not add significant bulk to the present VP shunt device design, and would function at low electrical power for device longevity without the need for large battery implants. Thus, there is a need in the art for improved systems and methods for detecting VP shunt failure.

SUMMARY OF THE INVENTION

[0007] Some embodiments of the invention disclosed herein are set forth below, and any combination of these embodiments (or portions thereof) may be made to define another embodiment.

[0008] In one aspect, a ventriculoperitoneal (VP) shunt device comprises a ventricular catheter, a drainage catheter, a flow control valve fluidly connecting the ventricular catheter to the drainage catheter, and one or more capacitive or resistive flow sensors positioned at one or more positions of a fluid flow path comprising the ventricular catheter, the flow control valve, and the drainage catheter.

[0009] In one embodiment, the one or more capacitive or resistive flow sensors are configured to measure a fluid flow rate via a variation in charge density within the fluid.

[0010] In one embodiment, the fluid comprises cerebrospinal fluid (CSF).

[0011] In one embodiment, the one or more capacitive or resistive flow sensors each comprise one or more emitter electrodes, one or more detector electrodes, and a voltage source electrically connected to at least one of the one or more emitter electrodes and/or the one or more detector electrodes. [0012] In one embodiment, the distance between the one or more emitter electrodes and one or more detector electrodes is in the range of 1 mm to 1000 mm.

[0013] In one embodiment, the one or more emitter electrodes and one or more detector electrodes each have lengths in the range of 0.1 mm to 50 mm, widths in the range of 0.1 mm to 1 mm, and thicknesses in the range of 0.1 mm to 1 mm.

[0014] In one embodiment, the one or more emitter electrodes and one or more detector electrodes each have lengths of 3 mm, widths of 0.4 mm, and thicknesses of 0.4 mm.

[0015] In one embodiment, the one or more emitter electrodes and one or more detector electrodes each comprise at least one of gold, silver, copper, titanium, steel, or nitinol.

[0016] In some embodiments, the one or more emitter electrodes and one or more detector electrodes are at least partially formed in one or more shapes.

[0017] In some embodiments, the one or more shapes are selected from: wire, cylinder, hollow cylinder, ring, torus, annulus, cube, prism, a rectangular prism, a sphere, curvilinear, bowed, curved, helix, double-helix, or spiral.

[0018] In one embodiment, the device further comprises an analog-to-digital converter (ADC) communicatively connected to the one or more capacitive or resistive flow sensors, and a microcontroller communicatively connected to the ADC.

[0019] In one embodiment, the one or more positions are associated with the ventricular catheter and comprise at least one of a first end of the ventricular catheter, a tip of the ventricular catheter, a position along the length of the ventricular catheter, a second end of the ventricular catheter proximate to the flow control valve, between and inline with the ventricular catheter and the flow control valve, surrounding either partially or entirely at least a portion of the ventricular catheter, within the walls of the ventricular catheter either partially or entirely, within a cavity of the ventricular catheter, and within a lumen of the ventricular catheter.

[0020] In one embodiment, the one or more positions are associated with the flow control valve and comprise at least one of surrounding either partially or entirely at least a portion of flow control valve, within the body of the flow control valve either partially or entirely, and within a cavity of the flow control valve.

[0021] In one embodiment, the one or more positions are associated with the drainage catheter and comprise at least one of between and inline with the flow control valve and the drainage catheter, a first end of the drainage catheter proximate to the flow control valve, a position along the length of the drainage catheter, a second end (i.e. tip) of the drainage catheter, a tip of the drainage catheter, surrounding either partially or entirely at least a portion of the drainage catheter, within the walls of the drainage catheter either partially or entirely, within a cavity of drainage catheter, and within a lumen of drainage catheter.

[0022] In one embodiment, the one or more capacitive or resistive flow sensors are configured to detect fluid flow rates in the range of 0.01 mL/min to 0.9 mL/min.

[0023] In another aspect, ventriculoperitoneal (VP) shunt system comprises a VP shunt device comprising a ventricular catheter, a drainage catheter, a flow control valve fluidly connecting the ventricular catheter to the drainage catheter, and one or more capacitive or resistive flow sensors positioned at one or more positions of a fluid flow path comprising the ventricular catheter, the flow control valve, and the drainage catheter, and a computing system communicatively connected to the VP shunt device, comprising a processor and a non- transitory computer-readable medium with instructions stored thereon, which when executed by the processor, perform steps comprising calculating at least one of a flow rate, a flow acceleration, and a valve state by measuring properties of the fluid with the one or more capacitive or resistive flow sensors, identifying failure of or blockage of the VP shunt device based on at least one of the flow rate, flow acceleration, and valve state, and providing an alert when failure of or blockage of the VP shunt device is identified.

[0024] In one embodiment, the computing system is communicatively connected to the VP shunt device via a wireless communication protocol comprising at least one of an 802.11 standard, cellular WAN infrastructure, Bluetooth, Bluetooth Low Energy (BLE) Zigbee, NearField Communication (NFC), and infrared.

[0025] In one embodiment, the processor of the computing system is configured to calculate fluid flow rate by performing steps comprising, applying a voltage for a period of time via one or more emitter electrodes of the one or more capacitive or resistive flow sensors to modify the charge density within a portion of a fluid in the VP shunt system, detecting the portion of the fluid with the modified charge density via one or more detector electrodes of the one or more capacitive or resistive flow sensors, measuring a time difference between applying the voltage via the one or more emitter electrodes and detecting the portion of the fluid with the modified charge density via one or more detector electrodes based on the detected response, and calculating a fluid flow rate based on the measured time difference and know distance between the one or more emitter electrodes and the one or more detector electrodes.

[0026] In one embodiment, the processor of the computing system is configured to calculate fluid acceleration by performing steps comprising measuring a change in capacitance due to variation in a dielectric value of a fluid moving in the system and calculating a flow acceleration based on the change in capacitance.

[0027] In one embodiment, the processor of the computing system is configured to measure valve state by performing steps comprising measuring a change in capacitance or resistance due to variation in a dielectric value or electrical resistance of a fluid moving in the system and determining the valve state by determining the geometry of the dielectric fluid before and after the valve.

[0028] In another aspect, method for identifying failure or blockage in a ventriculoperitoneal (VP) shunt comprises providing a VP shunt system as described above, calculating at least one of a flow rate, a flow acceleration, and a valve state by measuring properties of the fluid with the one or more capacitive or resistive flow sensors, identifying failure of or blockage of the VP shunt device based on at least one of the flow rate, flow acceleration, and valve state, and providing an alert when failure of or blockage of the VP shunt device is identified.

[0029] In one embodiment, the method is configured to identify failure or blockage in a VP shunt configured to accommodate fluid flow rates in the range of 0.01 mL/min to 0.9 mL/min. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The foregoing purposes and features, as well as other purposes and features, will become apparent with reference to the description and accompanying figures below, which are included to provide an understanding of the invention and constitute a part of the specification, in which like numerals represent like elements, and in which:

[0031] FIGs. 1A and IB depict an exemplary VP shunt device in accordance with some embodiments.

[0032] FIG. 2 depicts an exemplary VP shunt system in accordance with some embodiments.

[0033] FIG. 3 depicts a method for identifying failure in a ventriculoperitoneal (VP) shunt in accordance with some embodiments.

[0034] FIGs. 4A-4B depict an exemplary capacitive and/or resistive flow sensor working principle in accordance with some embodiments.

[0035] FIG. 5 depicts details of an exemplary mathematical model parameters, inputs, and constants of the exemplary capacitive and/or resistive flow sensor in accordance with some embodiments.

[0036] FIG. 6 depicts details of an exemplary mathematical model output indicating when the detector plate will sense a voltage differential across its plates relative to voltage emission of the exemplary capacitive and/or resistive flow sensor in accordance with some embodiments. [0037] FIG. 7 depicts theoretical vs measured delay to detected signal of the exemplary capacitive and/or resistive flow sensor in accordance with some embodiments.

[0038] FIGs. 8A and 8B depict an exemplary capacitive and/or resistive flow sensor plate design and wiring in accordance with some embodiments. In an aspect of the invention, FIG. 8A depicts the general wire electrode sensor design, which may include linear conductive wires comprising an emitter and detector. In another aspect of the invention, FIG. 8B depicts the general cylindrical electrode sensor design, which may include conductive cylinders comprising an emitter and detector.

[0039] FIGs. 8C and 8D are photographs of the flow sensor in accordance with some embodiments. FIG. 8C is a photograph of the exemplary flow sensor comprising the wire electrode flow sensor. FIG. 8D is a photograph of the exemplary flow sensor comprising the cylindrical electrode flow sensor.

[0040] FIG. 8E is a photograph of the exemplary cylindrical electrode flow sensor in a preferred embodiment whereby the exemplary cylindrical electrode flow sensor is inserted between the ventricular catheter and pressure outlet valve of a valve and shunt assembly. [0041] FIGs. 8F and 8G depict exemplary experimental setups for various aspects of the invention. In various embodiments, emitter plates are stimulated by a voltage-regulated power source, and an analog-to-digital converter (ADC) captures analog signals from the detector plates and sends them to digital input/output (I/O) pins of a microcontroller. FIG. 8F depicts a sensor testing experimental setup with flow driven by a gravity drain. FIG. 8G depicts sensor testing experimental setup with flow driven by a syringe pump. [0042] FIG. 9 depicts an exemplary global circuit design in accordance with some embodiments.

[0043] FIG. 10 depicts exemplary experimental normal saline flow velocity sensing performance in a straight tube without inline shunt-valve assembly in accordance with some embodiments. The emitter was programmed to apply 1 volt for 300 ms in all trials as this was found to be the optimal combination of voltage and duration. Three trials of eight different flow velocities were tested during three different sessions (entirely different days of experimentation). Different experimental sessions are denoted by different plotted colors.

[0044] FIG. 11 depicts an exemplary capacitive and/or resistive flow sensor experimental design in accordance with some embodiments.

[0045] FIG. 12 depicts low flow experimental results for flow rates of 0.029 mL/min, 0.035 mL/min, and 0.070 mL/min in accordance with some embodiments.

[0046] FIG. 13 depicts low flow experimental results for flow rates of 0.008 mL/min, 0.019 mL/min, and 0.029 mL/min in accordance with some embodiments.

[0047] FIG. 14 depicts low flow experimental results for flow rates of 0.004 mL/min, 0.009 mL/min, and 0.014 mL/min in accordance with some embodiments.

[0048] FIG. 15 depicts fast valve on/off experimental results in accordance with some embodiments.

[0049] FIG. 16 depicts slow valve on/off experimental results in accordance with some embodiments.

[0050] FIG. 17 depicts measurable valve position experimental results in accordance with some embodiments. [0051] FIG. 18 depicts an exemplary capacitive and/or resistive flow sensor experimental design utilizing a Codman VP shunt in accordance with some embodiments.

[0052] FIG. 19 depicts detecting shunt obstruction experimental results in accordance with some embodiments.

[0053] FIG. 20 depicts an enlarged view of region 1 of the experimental results shown in FIG. 19.

[0054] FIG. 21 depicts an enlarged view of region 2 of the experimental results shown in

FIG. 19.

[0055] FIG. 22 depicts resistance vs. flow sensitivity experimental results in accordance with some embodiments.

[0056] FIG. 23 depicts valve closure detection via resistance experimental results in accordance with some embodiments.

[0057] FIG. 24 depicts further details of the experimental results shown in FIG. 23.

[0058] FIG. 25 depicts low-flow velocity measured via capacitance experimental results in accordance with some embodiments.

[0059] FIG. 26 depicts additional low-flow velocity measured via capacitance experimental results in accordance with some embodiments.

[0060] FIGs. 27A-G depict one aspect of the invention with wire electrode sensor design and performance. FIG. 27A depicts dimensions of the wire electrode flow sensor used in this set of experiments; FIG. 27B depicts sensor response curves measured throughout a gravity drain experiment as configured in FIG. 8C. Time-to-peak (maximum voltage value) for high flow rates or time-to-value (minimum voltage value) for lower flow rates were analyzed for each curve to estimate flow rate; FIG. 27C depicts flow rate as a function of time-to-peak for five gravity drain trials, each trial consisting of approximately 15 distinct flow rate measurements; FIG. 27D depicts seconds-to-valley as a function of flow rate for five gravity drain trials, each trial consisting of approximately 15 flow rate measurements; FIG. 27E depicts fourth order polynomial fit of loglO of flow rate as a function of loglO of time-to-peaks; FIG. 27F depicts first order polynomial fit of loglO of flow rate as a function of loglO of time-to-valleys; and FIG. 27G depicts overall accuracy of the wire electrode sensor as determined by absolute error in predicted flow rate as a function of true flow rate.

[0061] FIGs. 28A-F depict another aspect of the invention with cylindrical electrode sensor design and performance. FIG. 28A depicts an exemplary cylindrical electrode flow sensor used in this set of experiments; FIG. 28B depicts sensor response curves measured 10 times at each of 10 different syringe-pump driven flow rates, using the experimental setup depicted in FIG.

8D. Seconds-to-peak was the feature used to estimate flow rate for each curve; FIG. 28C depicts flow rate as a function of time-to-peak for the five trials used to determine a flow estimation model; FIG. 28D depicts fourth order polynomial fit of loglO of flow rate as a function of loglO of time-to-peaks; FIG. 28E depicts overall accuracy of the cylindrical electrode flow sensor as determined by absolute error in predicted flow rate as a function of true flow rate; and FIG. 28F depicts sensor response during a gravity drain with transient manual catheter obstruction. [0062] FIGs. 29A-D depict another aspect of the invention with a secondary cylindrical electrode flow sensor characterization using normal saline. FIG. 29A depicts variation in sensor response with isolated change to stimulation voltage; FIG. 29B depicts variation in sensor response with isolated change to stimulation duration; FIG. 29C depicts power consumption as a function of stimulation duration demonstrates capacitance-like behavior with asymptotically decreasing charge rate after initial voltage application; and FIG. 29D depicts energy consumption as a function of stimulation duration demonstrating the low power requirements of the sensing element.

[0063] FIG. 30 depicts an exemplary computing environment in which aspects of the invention may be practiced in accordance with some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

[0064] It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clearer comprehension of the present invention, while eliminating, for the purpose of clarity, many other elements found in systems, devices, and methods for detecting ventriculoperitoneal (VP) shunt failure. Those of ordinary skill in the art may recognize that other elements and/or steps are desirable and/or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein. The disclosure herein is directed to all such variations and modifications to such elements and methods known to those skilled in the art.

[0065] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, exemplary methods and materials are described.

[0066] As used herein, each of the following terms has the meaning associated with it in this section.

[0067] The articles "a" and "an" are used herein to refer to one or to more than one (/.e., to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

[0068] "About" as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20%, ±10%, ±5%, ±1%, and ±0.1% from the specified value, as such variations are appropriate.

[0069] Ranges: throughout this disclosure, various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Where appropriate, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range. [0070] Referring now in detail to the drawings, in which like reference numerals indicate like parts or elements throughout the several views, in various embodiments, presented herein are systems, devices and methods for detecting VP shunt failure.

[0071] Disclosed herein are novel VP shunt failure detection systems with a sensing element which can be inserted into existing VP shunt systems during placement and related methods. In some embodiments, the sensor comprises conductive electrodes which induce a change in CSF charge density and subsequently measure a flow velocity-dependent response. Further disclosed are the sensor's design, working principle, and prototype benchtop performance for measuring CSF flow velocity through both a tube and through a VP shunt valve assembly. In some embodiments, the disclosed system relates to biomedical implants and a method for detecting VP shunt failure in its earliest phases via flow rate monitoring. In some embodiments, the disclosed system is capable of monitoring and logging CSF flow rate and VP shunt valve position as metrics for predicting shunt failure or shunt blockage.

[0072] Referring now to FIGs. 1-2, a VP shunt device 101 and system 100 are shown. In some embodiments, a VP shunt system 100 includes a VP shunt device 101 as described herein, and a computing system 102, such as computing system 2700 described herein, communicatively connected to the VP shunt device 101. The computing system 102 can be in communication with the VP shunt 101 via any suitable wireless or wired communication means and network protocols including, but not limited to, Ethernet, fiber optic, copper wire, gold wire, various 802.11 standards, cellular WAN infrastructures such as 3G, 4G/LTE, or 5G networks, Bluetooth, Bluetooth Low Energy (BLE) or Zigbee communication links, a TCP/IP network such as the Internet or an intranet, Near-Field Communication (NFC), infrared or any other method by which one electronic device is capable of communicating with another. In some embodiments, the includes a processor and a non-transitory computer-readable medium with instructions stored thereon, which when executed by the processor, perform steps comprising calculating at least one of a flow rate, a flow acceleration, and a valve state by measuring properties of the fluid with the one or more capacitive and/or resistive flow sensors, identifying failure of or blockage of the VP shunt system based on at least one of the flow rate, flow acceleration, and valve state, and providing an alert when failure of or blockage of the VP shunt is identified.

[0073] In some embodiments, the VP shunt device 101 comprises a ventricular catheter 103, a drainage catheter 105, a flow control valve 104 fluidly connecting the ventricular catheter 103 to the drainage catheter 105, and one or more capacitive and/or resistive flow sensors 106A-106N (collectively 106) positioned at one or more positions of a fluid flow path comprising the ventricular catheter 103, the flow control valve 104, and the drainage catheter 105.

[0074] One cause of shunt failure is blockage of the CSF flow path in the shunt which can occur at different locations of the shunt. For example, blockage may occur at the ventricular catheter 103 where the CSF enters the shunt, at the flow control valve 104, and/or at the drainage catheter 105 as a result of tissue growth over, around or into the catheter.

[0075] The use of capacitive and/or resistive flow sensors 106 provides many advantages over other flow sensing techniques. With capacitive and/or resistive flow sensors 106 ultra-low flow rates can be measured, CSF flow mechanics are not altered, they are MRI compatible, and operate on low power.

[0076] In some embodiments, the one or more capacitive and/or resistive flow sensors 106A-106N (collectively 106) can be placed at one or more locations along a fluid flow path of the VP shunt 101 including, but not limited to: a first end 198 (i.e. tip) of the ventricular catheter 103; any position along the length of the ventricular catheter 103; a second end 199 of the ventricular catheter 103 proximate to the flow control valve 104; between (i.e. inline with) the ventricular catheter 103 and the flow control valve 104 either under, within, or above the scalp; surrounding either partially or entirely at least a portion of the ventricular catheter 103; within the walls of the ventricular catheter 103 either partially or entirely; within a cavity (i.e. lumen) of the ventricular catheter 103; surrounding either partially or entirely at least a portion of flow control valve 104; within the body of the flow control valve 104 either partially or entirely; within a cavity of the flow control valve 104; between (i.e. inline with) the flow control valve 104 and the drainage catheter 105; a first end 198 of the drainage catheter 105 proximate to the flow control valve 104; any position along the length of the drainage catheter 105; a second end 199 (i.e. tip) of the drainage catheter 105; surrounding either partially or entirely at least a portion of the drainage catheter 105; within the walls of the drainage catheter 105 either partially or entirely; and/or within a cavity (i.e. lumen) of drainage catheter 105.

[0077] In some embodiments, the capacitive and/or resistive flow sensor 106 is an add-on device configured to be placed proximate to and/or around a ventricular catheter 103, valve 104, and/or drainage catheter 105. In some embodiments, the add-on capacitive and/or resistive flow sensor 106 is positioned within the hole in the skull bone (burr hole) which the ventricular catheter 103 passes through.

[0078] In some embodiments, the one or more capacitive and/or resistive flow sensors 106 are configured to measure a fluid flow rate via a variation in charge density within the fluid. In some embodiments, the fluid comprises cerebrospinal fluid (CSF). In some embodiments, the one or more capacitive and/or resistive flow sensors 106 are configured to detect fluid flow rates in the range of 0.01 mL/min to 0.9 mL/min.

[0079] In some embodiments, the one or more capacitive and/or resistive flow sensors 106 each comprise one or more emitter electrodes 107, one or more detector electrodes 108 and a voltage source electrically connected to at least one of the one or more emitter electrodes 107 and/or the one or more detector electrodes 108. In some embodiments, the electrodes (107, 108) can be used to measure capacitance and/or resistance when a current is actively passed between the electrodes (107, 108). In some embodiments the distance between the one or more emitter electrodes 107 and one or more detector electrodes 108 is approximately in the range of 1 mm to 1000 mm. In some embodiments, the one or more emitter electrodes 107 and one or more detector electrodes 108 each have lengths approximately in the range of 0.1 mm to 50 mm, widths approximately in the range of 0.1 mm to 1 mm, and thicknesses approximately in the range of 0.1 mm to 1 mm. In some embodiments, the one or more emitter electrodes 107 and one or more detector electrodes 108 each have lengths of about 3 mm, widths of about 0.4 mm, and thicknesses of about 0.4 mm. In some embodiments, the one or more emitter electrodes 107 and one or more detector electrodes 108 each comprise at least one of gold, silver, copper, titanium, steel, or nitinol.

[0080] In some embodiment, flow sensors 106 may comprise one or more gold-plated wires oriented parallel to the flow, coincident with the inner catheter wall, axially offset, and diametrically opposed comprising each the emitter electrodes 107 and detector electrodes 108 (FIG. 8C). In some embodiments, an exemplary cylindrical electrode design comprises two gold- plated cylinders with outer surfaces coincident with the inner catheter wall, each comprising the emitter and detector (FIG. 8D). In some embodiments, the catheter segment of all sensors are formed from or manufactured from silicone. The cylindrical electrode flow sensor was preferably inserted between the ventricular catheter and pressure outlet valve of a valve and shunt assembly, is shown in FIG. 8E.

[0081] In some embodiments, flow sensor 106 may comprise one or more linear conductive wires comprising an emitter and detector as shown in FIG. 8A. The CSF flows from the emitter to the detector. In an alternative embodiment, the flow sensor may be based on a cylindrical electrode sensor design comprising conductive cylinders including an emitter and detector as shown in FIG. 8B. The CSF flows from the emitter to the detector. For example, the sensing element may be cylindrical and may measure 2 mm in diameter and 17 mm in length such that the sensing element may be inserted inline with existing shunt systems in various locations as shown in FIG. 2 and described above. The inner diameter of the catheter within the sensing element was expanded to 2 mm from the typical shunt catheter diameter of 1 mm in order to preserve a clear 1 mm inner diameter cylindrical flow channel for CSF to flow unimpeded. [0082] In some embodiments, electrodes (107, 108) are in direct electrical contact with the fluid. In some embodiments, electrodes (107, 108) are electrically insulated from the fluid.

[0083] In some embodiments, the capacitance across the electrodes (107, 108) varies according to variation in the dielectric value of the fluid. In some embodiments, an electrical current is passed between the electrodes (107, 108) and through the fluid. In some embodiments, an electrical field is formed between the electrodes (107, 108) and through the fluid. In some embodiments, capacitance across the electrodes (107, 108) varies according to variation in the dielectric value of the fluid flowing through the system. In some embodiments, voltage measured across the electrodes (107, 108) varies according to variation in the electrical resistance of the fluid flowing through the system.

[0084] In some embodiments, the valve 104 is positioned between the electrodes (107, 108) of the capacitive and/or resistive flow sensor 106. In some embodiments, the valve 104 is positioned outside the electrodes (107, 108) of the capacitive and/or resistive flow sensor 106. In various aspects of the invention, flow sensors 106 may include different types of geometries, or be at least partially formed in one or more shapes. In some embodiments, the different types of geometries, or the one or more shapes are selected from square, rectangle, circle, semi-circle, polygon, cube, prism, rectangular prism, cylinder, hollow cylinder ring, annulus, torus, wire, curved, curvilinear, spiral, helix, double-helix or the like. In some embodiments, flow sensors 106 may comprise one or more curved regions or curved surfaces in the geometries of the sensors. In one embodiment, the sensor 106 may comprise a wire electrode design that may include linear conductive wires. In an alternative embodiment, the sensor 106 may comprise a cylindrical electrode design. In an alternative embodiment, the sensor 106 may comprise a quadrilateral (square or rectangular) electrode design.

[0085] In some embodiments, the VP shunt device 101 further includes an analog-to-digital converter (ADC) communicatively connected to the one or more capacitive and/or resistive flow sensors 106, and a microcontroller communicatively connected to the ADC.

[0086] In some embodiments, the ADC and microcontroller along with other suitable electronics to read and store sensor data overtime are implantable. In some embodiments, the VP shunt device 101 includes a transceiver configured to wirelessly transmit logged data to the computing system 102.

[0087] FIG. 3 is a flowchart depicting a method for identifying failure in a ventriculoperitoneal (VP) shunt. In one embodiment, the method 200 starts at Operation 201 where a VP shunt system 100 is provided. At Operation 202 at least one of a flow rate, a flow acceleration, and a valve state is calculated by measuring properties of the fluid with the one or more capacitive and/or resistive flow sensors 106. At Operation 203 failure of or blockage of the VP shunt device 101 is identified based on at least one of the flow rate, flow acceleration, and valve state. The method 200 ends at Operation 204 where an alert is provided when failure of or blockage of the VP shunt device 101 is identified.

[0088] In some embodiments, steps for calculating a fluid flow rate include: applying a voltage for a period of time via one or more emitter electrodes 107 of the one or more capacitive and/or resistive flow sensors 106 to modify the charge density within a portion of a fluid in the VP shunt system 101; detecting the portion of the fluid with the modified charge density via one or more detector electrodes 108 of the one or more capacitive and/or resistive flow sensors 106; measuring a time difference between applying the voltage via the one or more emitter electrodes 107 and detecting the portion of the fluid with the modified charge density via one or more detector electrodes 108 based on the detected response; and calculating a fluid flow rate is based on the measured time difference and know distance between the one or more emitter electrodes 107 and the one or more detector electrodes 108.

[0089] In some embodiments, steps for calculating a fluid acceleration include measuring a change in capacitance due to variation in a dielectric value of a fluid moving in the VP shunt device 101, and calculating a flow acceleration based on the change in capacitance. In some embodiments, the measured flow acceleration of the fluid in the VP shunt device 101 is used to estimate fluid velocity within the VP shunt device 101. In some embodiments, the measured flow acceleration of the fluid in the VP shunt device 101 is used to predict occlusion and/or failure of the VP shunt device 101.

[0090] In some embodiments, the working principle of the described system 100 for measuring CSF flow acceleration is shown in FIGs. 4A-4B, and is described as follows. As CSF flow accelerates, there is wave of compressed dielectric material proportional to the magnitude of flow acceleration which propagates through the fluid. As this wave passes between the conducting electrodes (107, 108; as shown in FIGS. 8B & 8C), the measured capacitance changes as a result of the composition of the dielectric material being transiently altered.

Therefore, the magnitude of CSF flow acceleration and/or flow rate through the capacitive flow sensor 106 in the VP shunt device 101 can be measured using the rate of change of capacitance across the conducting electrodes (107, 108).

[0091] Alternatively, and/or simultaneously, as this wave passes between the conducting electrodes (107, 108), the measured resistance changes as a result of the composition of the dielectric material being transiently altered. Therefore, the magnitude of CSF flow rate through the resistive flow sensor 106 in the VP shunt device 101 can be measured using the rate of change of resistance across the conducting electrodes (107, 108).

[0092] Experimentation has reliably demonstrated that the described method enables accurate calculation of fluid flow velocity as low as 0.004 mL per minute, over twice as slow as the slowest documented flow rate of CSF within a VP shunt.

[0093] In some embodiments, steps for calculating a valve state include measuring a change in capacitance due to variation in a dielectric value of a fluid moving in the VP shunt device 101 or measured voltage due to variation in electrical resistance of a fluid moving in the VP shunt device 101, and determining the valve state by determining the geometry of the dielectric fluid before and after the valve 104. In some embodiments, the measured valve position is used to estimate fluid pressure in the VP shunt device 101. In some embodiments, the geometry of the dielectric fluid before and/or after the valve 104 is used to determine the valve state. In some embodiments, measured valve state is used to predict occlusion and/or failure of the VP shunt device 101.

[0094] In some embodiments, the working principle of the described method for measurement of valve function/state is as follows. When a pressure outlet valve 104 is positioned between two conducting electrodes (107, 108), pressure outlet valve opening and closing alters the associated capacitor CSF dielectric value and/or electrical resistance, which in turn induces a change in the capacitance and/or resistance measured by the capacitive and/or resistive flow sensor 106, and thus provides a reliable method for determining exact shunt valve 104 position. Experimentation has reliably demonstrated a measurable change in capacitance proportional to the degree to which the catheter lumen is occluded.

[0095] The pressure outlet valve opening and closing further alters the electrical resistance between the two conducting electrode plates, and thus provides a reliable method for determining exact shunt valve position. Experimentation has reliably demonstrated a measurable change in measured electrical resistance proportional to the degree to which the catheter lumen is occluded.

[0096] When a valve 104 is positioned outside of two conducting electrodes (107, 108) (as opposed to in between them), CSF valve 104 opening and closing is detectable due to altered CSF dielectric geometry. Experimentation has reliably demonstrated that by measuring capacitance across two conductive electrodes, the position of a valve 104 outside of the two electrodes can be reliably determined.

[0097] In some embodiments, artificial intelligence and/or machine learning is utilized to analyze the data to enable early detection of shunt failure prior to the manifestation of its clinical sequelae. EXPERIMENTAL EXAMPLES

[0098] The invention is now described with reference to the following Examples. These Examples are provided for the purpose of illustration only and the invention should in no way be construed as being limited to these Examples, but rather should be construed to encompass any and all variations which become evident as a result of the teaching provided herein.

[0099] Without further description, it is believed that one of ordinary skill in the art can, using the preceding description and the following illustrative examples, make and utilize the present invention and practice the claimed methods. The following working examples therefore, specifically point out exemplary embodiments of the present invention, and are not to be construed as limiting in any way the remainder of the disclosure.

[0100] Sensing Mechanism: Initial design requirements included a fully implantable system (no external hardware so as to remove user interference) which is capable of automatically alerting the patient at any given time when shunt failure is developing. An implantable and low power solution would fulfill these requirements. To this end, the sensor was designed such that its sensing mechanism interacted directly with CSF as opposed to transcutaneous action so as to minimize necessary power. The inherent conductivity of CSF is central to the described approach. An emitter comprised of two conducting plates lining the inner surface of the shunt catheter applies a temporary voltage to alter the distribution of ionic charges within the CSF. A detector plate at a known position is downstream to the emitter. After a short voltage pulse is applied by the emitter at a known time, the detector is activated and awaits the signal downstream. Based on the delay to voltage detection and known position of the emitter relative to the detector, a flow velocity can be computed. This mechanism is depicted in FIGs.

4A-4B.

[0101] Working Principles: Referring to FIGs. 4A-4B, a brief voltage pulse applied across the emitter induces a variation in charge density within the fluid which then flows downstream and induces a detectable change potential difference across detector plates. The delay between voltage application and detected response is used to determine fluid flow rate. Detected response is positive at first, then eventually zeroes and deflects negative, then settles back to zero as the charged cloud passes over and beyond the detector. The detected voltage deflection may be negative first if the electrical polarity of the emitting electrode is reversed.

[0102] Sensor working principles for flow rate measurement will be as follows. 1) Homogenously charged CSF will flow through the catheter and over the emitter and detector;

2) a brief voltage pulse will be applied across the emitter plates and induces a positively and negatively charged cloud of ions in local CSF; 3) Continued CSF flow will carry the charged ion clouds downstream; 4) the charged cloud will begin to induce a detectable difference in potential across detector plates; 5) as the charged clouds will pass further over the detector plates, the detected difference in potential will maximize; 6) the difference in potential diminishes as the charged cloud continues downstream; 7) the difference in potential across the detector plates will return to baseline. Flow rate will be estimated using time-to-peak of the response signal and the known distance between the emitter and detector plates.

[0103] As shown in FIG. 4A, a set of conductive electrodes lines the inner surface of the flow channel within the sensor and electrically will interact with CSF as it flows by. The first two electrodes which CSF encounter comprise the emitter, and the final two electrodes comprise the detector. When a voltage is applied across the emitter electrodes, a cloud of relative positive charge will be formed near the negative electrode, and a cloud of relative negative charge will be formed near the positive electrode. Upon removal of the emitter voltage, ions within each cloud will begin to diffuse towards electrical neutrality through Brownian motion. This process takes time and does not complete before the CSF reaches the detector plates when flowing at typical flow rates of 0.01-1 mL/min. The charged ion clouds then serve as a battery by inducing a measurable voltage across detector electrodes. This detected voltage first rises, peaks, and then returns to baseline as the charged clouds pass by the detector. Given a known time of emitter stimulation, a known time of arrival at the detectors, and a known distance between the emitter and detector electrodes, a flow rate will be determined.

[0104] Mathematical Model: A mathematical model simulating detection delays was developed to inform initial prototype design. Parameters included emitter and detector size and spacing, applied voltage, voltage duration, flow velocity, and catheter inner diameter. These parameters were tuned until a range of dimensions capturing the target flow rates of 0.01 mL/minute to 0.3 mL/minute were captured. A summary of the mathematical model is shown in: FIG. 5 showing model parameters, inputs, and constants; FIG. 6 showing an example of model output, indicating when the detector plate will sense a voltage differential across its plates relative to voltage emission; and FIG. 7 showing theoretical vs measured delay to detected signal. [0105] Sensor and Circuit Design: Two electrode geometries were tested including a wire electrode design as shown in FIG. 8A and a cylindrical electrode design as shown in FIG. 8B. The dimensions of the exemplary experimental flow sensor as informed by the mathematical model and experimental tuning are shown in FIG. 8A. The wire electrode design comprised two gold- plated wires oriented parallel to the flow, coincident with the inner catheter wall, axially offset, and diametrically opposed comprising each the emitter and detector (FIG. 8C). The cylindrical electrode design comprises two gold-plated cylinders with outer surfaces coincident with the inner catheter wall, each comprising the emitter and detector (FIG. 8D). The catheter segment of all sensors was made up of silicone. The cylindrical electrode flow sensor, preferably inserted between the ventricular catheter and pressure outlet valve of a valve and shunt assembly, is shown in FIG. 8E.

[0106] In one embodiment, the flow sensor may comprise of linear conductive wires comprising an emitter and detector as shown in FIG. 8A. The CSF flows from the emitter to the detector. In an alternative embodiment, the flow sensor may be based on a cylindrical electrode sensor design comprising conductive cylinders including an emitter and detector as shown in FIG. 8B. The CSF flows from the emitter to the detector. For example, the sensing element may be cylindrical and may measure 2 mm in diameter and 17 mm in length such that the sensing element may be inserted inline with existing shunt systems in various locations as shown in FIG. 2 and described above. The inner diameter of the catheter within the sensing element was expanded to 2 mm from the typical shunt catheter diameter of 1 mm in order to preserve a clear 1 mm inner diameter cylindrical flow channel for CSF to flow unimpeded. [0107] Experimental Setup: Flow of either normal saline (0.9% NaCI) or a CSF (Ecocyte Bioscience) was driven through the sensor by either gravity through a CODMAN® CERTAS® Plus Programmable Valve and Shunt Assembly (FIG. 8F) or a New Era® 1000 One Channel Programmable Syringe Pump (FIG. 8G). In each case, a microcontroller (AT ega328P) controlled a bridge which operated the emitter relay, thereby applying a voltage-regulated source to the emitter. In all experiments, analog voltages from the detector were converted to digital signals using a 24-bit analog-to-digital converter (ADC) and stored in memory by the microcontroller. For gravity-driven flow (FIG. 8F), a CGOLDENWALL® Precision Digital Analytical Balance measured the mass of drained fluid in real-time and transferred this data to the microcontroller for determination of true flow rates.

[0108] The inner diameter of most VP shunt catheters is approximately 1 mm as shown by the entry and exit tubes. In the example shown, the sensing element is contained within the 2 mm ID segment. In the example shown, the emitter comprises two conducting plates each measuring 3 x 0.4 x 0.4 mm and oriented as shown, for example, in 107 of FIG. 8A. In the example shown, the detector comprises two conducting plates each measuring 3 x 0.4 x 0.4 mm and oriented as shown, for example, in 108 of FIG. 8A. Fluid flows from the emitter to the receiver. In the example shown, the entire sensing element measures 17 mm in length and 2 mm in diameter and can be inserted between portions of any existing VP shunt system. In the example shown, the emitter plates are connected to negative and positive leads. In the example shown, the detector plates are connected directly to an analog-to-digital converter

(ADC) pins A0 and Al as shown in FIG. 8A. [0109] The sensing element was controlled using a microcontroller which also logged all measured data as seen in Fig. 8F. The same microcontroller also controlled a syringe infusion pump for controlled fluid flow rates, a voltage regulator for controlled voltage application, and an analog-to-digital converter (ADC) for voltage measurement across the detector as seen in Fig. 8G. A diagram depicting the global device circuit is also shown in FIG. 9.

[0110] The sensing element as described in FIG. 4A is shown within the blue catheter. This catheter is connected to a syringe infusion pump which injects known flow rates. A voltage regulator is used to apply a constant voltage. A relay is used to toggle voltage applied / not applied. An ADC samples the detector plates during measurement windows. A microcontroller controls the elements of the system and logs data.

[0111] Experimental Design: An initial benchtop validation test was performed with a simple straight catheter measuring 1 mm in inner diameter without an inline shunt valve system to validate flow sensitivity of the initial prototype. Normal saline was used as test fluid. Flows including 0.01, 0.02, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 mL / minute were established using the programmable syringe pump. The sensor was then activated, and the flow response curve was recorded for each trial. Three trials were conducted at each flow velocity, and the entire process was repeated on three separate days to evaluate sensor consistency over time. A voltage of 1 V was applied for a duration of 300 ms for all trials, and then the detector was activated immediately after the voltage pulse was removed. The results of this experiment are shown in FIG. 10. [0112] A second set of experiments was conducted to measure flow rates when the sensing element was inserted into a shunt and valve assembly. The sensing element was coupled to the ventricular catheter on one end and the shunt valve on the other end. A simple gravity drain driven by the hydrostatic pressure of water column was then connected to the ventricular catheter and flow was measured at various intervals throughout an eight-hour draining trial. True flow rate was measured by tracking the weight of dispensed water over time. Sensor flow estimates were then compared to true flow estimates. The results of this experiment are shown in FIGs. 19, 20, 21, and 22.

[0113] Data Analysis and Results: Recorded flow measurements from each experiment were analyzed using MATLAB (R2022b). The results show that the flow sensor is sensitive over the range of relevant CSF flow velocities. The sensing element operates on very low power given its direct interaction with CSF and can therefore readily be integrated into an implantable, battery-powered VP shunt failure detection system which updates patients automatically at all times of the day if there is progressive shunt failure. Use of a reference electrode as described can make the sensing mechanism robust to changes in environmental conditions such as temperature and CSF content. The measured sensor behavior agrees closely with the mathematical model which supports the hypothesis for the sensing mechanism. The compact dimensions of the sensor and the ability to bend it enables implantation into a burr hole and under the scalp with minimal additional bulk.

[0114] Measuring Flow Velocity Using Capacitance: FIGs. 11-14 describe experimental details and results for measuring flow velocity via capacitance. FIG. 11 shows an overview of the design of the experiment. A microcontroller couple to a linear actuator was used to control input flow provided by a 1 mL input syringe to a first catheter tube. A 3-way valve was used to direct the flow to a 60 mL reservoir syringe or to a second catheter tube including the capacitive flow sensor electrodes and 1 mL receiving syringe. For this experiment a phone was used to record capacitance values from a capacitance meter connected to the electrodes.

[0115] FIG. 12 shows that low flow rates of 0.029 mL/min, 0.035 mL/min, and 0.070 mL/min are detectable via capacitance measurements. FIG. 13 shows that low flow rates of 0.008 mL/min, 0.019 mL/min, and 0.029 mL/min are detectable via capacitance measurements. FIG. 14 shows that low flow rates of 0.004 mL/min, 0.009 mL/min, and 0.014 mL/min are detectable via capacitance measurements. For FIGs. 12-14, the top left plots show actuator on/off periods vs. time, the bottom left plots show measured capacitance over time in seconds, the top right plots show capacitance immediately after flow is turned on, and the bottom right table show integrated capacitance values for each flow rate along with P and T test values.

[0116] FIGs. 15-17 show experimental results for fast valve on/off, slow valve on/off, and valve position measurements with capacitance, respectively. For the fast valve on/off results shown in FIG. 15, each pinch was performed over 6 seconds. As indicated by the long arrow, notice the gradual change with slow pinch release.

[0117] For the slow valve on/off results shown in FIG. 16, the valve was opened/closed over approximately 30 seconds. The takeaway from this is that in addition to flow rates, exact valve position can be measured using capacitance. [0118] FIG. 17 shows that valve position is measurable without injecting any current. For this experiment, the capacitance plates (electrodes) were electrically insulated with no current flowing in the liquid.

[0119] FIGs. 18-22 describe experimental details and results for measuring flow through a VP shunt, in this example a Codman shunt. FIG. 18 shows an overview of the design of the experiment. A 60 mL reservoir syringe was used to supply fluid to a catheter that included a Codman valve. The catheter comprised resistive flow sensors communicatively connected to a microcontroller via an analog-to-digital converter (ADC). In some embodiments, an optical drip sensor was used to monitor the fluid exiting the catheter.

[0120] FIG. 19 depicts overnight experimental results including detecting shunt obstruction. The top plot shows drip count vs. time in hours, the middle plot shows flow rate in mL/min vs. time in hours, and the bottom plot shows mV which is proportional to resistance vs. time in hours. An intentional peritoneal catheter obstruction was performed as indicated in FIG. 19. FIGs. 20-21 depict an enlarged views of region 1 and region 2, respectively, of the experimental results shown in FIG. 19. As shown in FIGs. 20-21, resistance is highly sensitive to flow velocity. FIG. 22 is a plot showing resistance vs. flow rate (i.e. sensitivity). Sensitivity maximizes at low flow rates.

[0121] FIGs. 23-24 depict detecting valve open/closed state via resistance. The top plots show drip count vs. time in hours, and the bottom plots show mV which is proportional to resistance vs. time in hours. FIG. 24 shows that slightly different drip rates (i.e. true flow rates) are detectable via resistance. [0122] FIGs. 25-26 depict low-flow velocity measured via capacitance experimental results.

The plots of FIG. 25 from top to bottom show capacitance in nF vs. sample number for flow rates of 0.3 mL/min, 0.2 mL/min, 0.1 mL/min, and 0.02 mL/min, respectively. FIG. 26 is a plot showing the change in capacitance in nF vs. flow rate in mL/min.

[0123] Accordingly, in one aspect of the invention, the disclosed system and sensor demonstrate flow sensitivity down to 0.01 mL / minute through a CSF shunt valve assembly and can measure flows up to at least 0.3 mL / minute, the physiologic rate of CSF generation. These tasks are accomplished in the device using very low power, therefore making this flow sensing method desirable for use in an implantable and battery-powered VP shunt failure detection system. The disclosed system and sensor offers a chance for improved awareness of shunt health in the tens of thousands of patients in the United States whose well-beings rely on the continued functionality of their shunting system.

[0124] Wire Electrode Flow Senor Test Results: The exact dimensions of the wire electrode sensor are detailed in FIG. 27A. The voltages detected during a typical gravity drain of normal saline through the wire electrode flow sensor are superimposed in FIG. 27B. The hypothesized voltage peaks described in FIG. 4A were observed in the detector response, along with the addition of unexpected dips in voltage consistently occurring at lower flow rates of < 0.3 mL/min (forming the valleys ultimately used in time-to-valley modeling). Seconds-to-peak (FIG. 27C) and seconds-to-valley (FIG. 27D) as functions of flow rate were plotted. A fourth order polynomial was fit to the loglO of seconds-to-peak vs loglO of flow rate (FIG. 27E), and a first order polynomial was fit to loglO of seconds-to-valley vs loglO of flow rate (FIG. 27F). The sensor achieved an average percent error of 7.2% in flow rate measurement evaluated against a total of 241 true flow rate measurements over a broad range of flow (0.01 - 0.9 mL/min) (FIG. 27G).

[0125] Cylindrical Electrode Flow Sensor Test Results: The exact dimensions of a longitudinal midline cross-section of the cylindrical electrode flow sensor are detailed in FIG. 28A. The voltages detected by the cylindrical electrode flow sensor during the syringe pump- driven a CSF trials are superimposed in FIG. 28B. Response curves were in close alignment with the hypothesized voltage peaks described in FIG. 4A. Seconds-to-peak as a function of flow rate for the five trials used to develop the flow estimation model alongside mathematical models corresponding to earliest theoretical detection time (Model 1) and latest theoretical detection time (Model 2) with intervening area shaded gray are plotted in FIG. 28C; the shapes of the empirically and mathematically derived seconds-to-peak vs flow rate responses mirrored one another as parabolic curves. A fourth order polynomial was fit to loglO of seconds-to-peak vs loglO of flow rate (FIG. 28D). The average percent error of the cylindrical flow sensor using the polynomial fit to generate flow estimations over a flow range of 0.01 - 0.9 mL/min was 4.2% (FIG. 28E). Detected voltages for successive measurements during the VP shunt manual obstruction trial are shown in FIG. 28F. Obstructed trials exhibited a flattened profile compared to unobstructed trials, which peaked in response to nonzero flow of normal saline.

[0126] Secondary Sensor Characterization Results: Detected voltage in response to variation in stimulation voltage at constant flow rate and stimulation duration is shown in FIG.

29A. The time-to-peak did not change appreciably with changing stimulation voltage. Signal clarity is compromised at stimulation voltage of 0.50 V with the cylindrical plate design.

Detected voltage in response to variation in stimulation duration at constant flow rate and stimulation voltage is shown in FIG. 29B. The time-to-peak did not change appreciably with changing stimulation duration. Signal clarity was not comprised as low as 0.50 sec stimulation duration, as evidenced by the preservation of a clear signal peak at 0.50 sec stimulation duration. Power consumption as a function of stimulation duration at various flow rates of normal saline is shown in FIG. 29C. The power curve exhibits capacitance-like behavior with asymptotically decreasing charge rate after initial voltage application. Energy consumption as a function of stimulation duration at various flow rates of normal saline is shown in FIG. 29D.

Fewer than 40 pJoules are consumed by the sensing element during one flow rate measurement with a pulse duration of 0.5 seconds.

[0127] The disclosed sensing element (e.g., flow sensor) achieved accurate measurements of flow rates ranging from 0.01 - 0.9 mL I min while consuming less power than direct thermal anemometry solutions by a factor of over 400. The disclosed flow sensor employs a novel flow sensor leveraging the time-dependent dispersion of a charged fluid through Brownian diffusion The time it takes CSF to flow ~ 2 cm through the catheter between the two detection points matches the time associated with CSF's transient return to spatial electrical homogeneity. This congruence in time allows for a viable method to measure flow using the disclosed compact sensor design as described herein. Due to the combination of CSF's constant fluid mechanical flow and the partial electrical conductivity of CSF, the fluid between the electrodes effectively functions as a hybrid electrical resistor and capacitor, which allows for some flow of current while also retaining charge after the external voltage is removed. Because the disclosed method involves applying an EM field directly through a segment of CSF, the sensing element saves significant power as it only requires 37.5 pJoules per flow measurement. In direct thermal anemometry solutions, the thermistor is placed in direct contact with CSF to minimize transcutaneous heat loss associated with indirect thermal anemometry, making direct solutions more power-efficient per flow measurement than indirect thermal anemometry; yet the direct thermal anemometry solution described in Qin et al. [Qin et al. (2017). Inline shunt flow monitor for hydrocephalus. Analytical Chemistry, 89(15), 8170-8176. https //doi.org/10.1021/acs.anakhem.7b02034] still required ~17 millijoules per flow measurement, which is ~450 times higher than the power required in our present solution.

[0128] The disclosed flow sensor is capable of reporting accurate measurement in variable conditions in large part due to the implementation of a reference electrode. The emitter effectively serves as a reference for the detector, abstracting away several characteristics of the fluid which are subject to temporal variation. The chemical composition of CSF may change over time with the variable cell counts, the presence or absence of blood, and variable protein, ion, and sugar levels. Despite the significantly differing chemical compositions of normal saline and a CSF, flow rates of both fluids were accurately measured using the described time-to-peak algorithm across typical VP shunt flow rates. Furthermore, no effort was made to control the pre-stimulation state of ionization in the fluid. Given repeatable flow rate sensor accuracy results in this setting, it follows that the pre-existing state of ionization of the fluid does not significantly affect the accuracy of the flow sensor. Unlike existing thermal anemometry solutions, it stands to reason that temperature variation would similarly have negligible effect on the transit time of the ion cloud from emitter to detector. This is unlike thermal anemometry solutions, which are inherently temperature dependent.

[0129] It was found that electrode geometry influenced the maximum achievable accuracy of flow rate measurement. The averaged percent errors in flow rate measurement for the wire and cylindrical electrode flow sensors were 7.2% and 4.2%, respectively, results which are comparable to the most accurate current solutions. These accuracies were tested for flows ranging from 0.01 - 0.9 mL/min, which covers reported physiologic CSF shunt flow rates. The physical explanation for the observed difference may relate to the total area of available conductive surface available for interaction with the fluid. With more conductive surface contacting the fluid in the cylindrical emitter as compared to the wire emitter, the cylindrical emitter likely generated more spatially distinct ion clouds. Similarly, the larger detector surface likely facilitates improved detection of potential differences within the ion cloud, hence improving flow sensor accuracy. Being symmetrical, a cylindrical electrode design flush with the catheter's inner wall offers the benefit of no alteration in CSF flow mechanics (other than slightly differing drag coefficients of the conducting surface compared to the silicone tubing). Future iterations of this technology may employ a design with one or more emitters and multiple detectors spaced throughout the catheter, therefore allowing for characterization of the full flow profile throughout the catheter.

[0130] Several factors influence the ideal stimulus voltage applied by the emitter. Stimulus voltages below 0.7 Volts resulted in a low detected voltage and a poor signal-to-noise ratio on the detector plate, presumably due to insufficient electrically induced spatial variation in CSF charge density at the emitter. It should be noted that 0.7 Volts as a lower stimulus voltage threshold is unique to the cylindrical emitter geometry evaluated in this study, because this voltage threshold is associated with a particular geometry-dependent electromagnetic (EM) field formed between the emitter's positive and negative poles. To avoid unwanted chemical reactivity with the ionic contents CSF, the upper stimulus voltage threshold lies below the reduction potentials of each ion capable of precipitation upon reduction in CSF (Na+: 2.71 V, K+: 2.93 V, Ca2+: 2.87 V, Mg2+: 2.37 V, CI-: 1.36 V) and below the standard potential for hydrolysis (1.23 V). While early solutions intentionally created electrolytic bubbles for velocity tracking, this method for fluid velocity measurement proved challenging with frequent bubble adherence to the catheter wall. A value of 1.1 Volts was therefore selected for high signal-to- noise ratios without the significant risk of driving ionic reduction and precipitation or hydrolysis.

[0131] As a standalone and compact insertable component, the sensing element is compatible with existing commercial shunt systems and can also be used to retrofit previously implanted shunt systems. After implanting the tip of the ventricular catheter into the ventricles, neurosurgeons will connect the sensor such that the emitter is adjacent to the ventricular catheter, and the detector is adjacent to the proximal side of the shunt valve. By orienting the sensor as such, CSF will flow from emitter to detector as intended. Positioning the sensor directly adjacent to the valve lends neurosurgeons ease of access to the sensor insertion site during routine shunt implantation. Convenient retrofitting of previously implanted shunt systems will also be possible during revisions with the sensor being directly adjacent to the valve, where the surgeon will have already established surgical access. The novel sensing mechanism allows for a compact 2 cm design which is smaller than pressure sensitive silicone membrane flow sensors which span over 10 cm along the length of the catheter. Future iterations of this technology may be embedded directly into the wall of the catheter of a smart shunt, which would presumably have other sensory data (patency, pressure) to holistically monitor overall shunt health. Connection of the sensor distal to the valve would also be possible.

[0132] The use of metal electrodes as described in the flow sensing element is associated with several potential limitations. Metals selected for the electrodes must be compatible with radiographic and magnetic resonance imaging to avoid the introduction of significant imaging artifact and device migration or loss of function under a power external EM field. Any of these complications would be an unacceptable clinical outcome, given the potential danger to the patient and compromise of image quality, which provides critical information necessary for optimal medical management of patients with hydrocephalus. Furthermore, any metal immersed in aqueous solution has the potential to corrode. To prevent plate corrosion, all prototyped electrodes were coated in a thin layer of gold. Close inspection of electrode plates of the emitter and detector in normal saline and artificial CSF revealed no corrosion after immersion for over 60 days. Other corrosion resistant metals such as copper would be similarly sensible selections as corrosion-resistant electrode coatings in future iterations of this device.

[0133] Accordingly, in one aspect of the invention, a novel method for sensing the flow rate of CSF in a VP shunt which achieves high accuracy in benchtop testing across a broad flow range of normal saline and artificial CSF (0.01 - 0.9 mL/min) while using significantly less power.

Further, the sensing element is insertable into existing shunt and valve assemblies and does not alter CSF flow mechanics. The described CSF flow rate sensing method offers the opportunity for a power-efficient implantable VP shunt monitor requiring minimal device maintenance.

COMPUTING ENVIRONMENT

[0134] In some aspects of the present invention, software executing the instructions provided herein may be stored on a non-transitory computer-readable medium, wherein the software performs some or all of the steps of the present invention when executed on a processor.

[0135] Aspects of the invention relate to algorithms executed in computer software. Though certain embodiments may be described as written in particular programming languages, or executed on particular operating systems or computing platforms, it is understood that the system and method of the present invention is not limited to any particular computing language, platform, or combination thereof. Software executing the algorithms described herein may be written in any programming language known in the art, compiled or interpreted, including but not limited to C, C++, C#, Objective-C, Java, JavaScript, MATLAB, Python, PHP, Perl, Ruby, or Visual Basic. It is further understood that elements of the present invention may be executed on any acceptable computing platform, including but not limited to a server, a cloud instance, a workstation, a thin client, a mobile device, an embedded microcontroller, a television, or any other suitable computing device known in the art. [0136] Parts of this invention are described as software running on a computing device. Though software described herein may be disclosed as operating on one particular computing device (e.g. a dedicated server or a workstation), it is understood in the art that software is intrinsically portable and that most software running on a dedicated server may also be run, for the purposes of the present invention, on any of a wide range of devices including desktop or mobile devices, laptops, tablets, smartphones, watches, wearable electronics or other wireless digita l/cel lula r phones, televisions, cloud instances, embedded microcontrollers, thin client devices, or any other suitable computing device known in the art.

[0137] Similarly, parts of this invention are described as communicating over a variety of wireless or wired computer networks. For the purposes of this invention, the words "network", "networked", and "networking" are understood to encompass wired Ethernet, fiber optic connections, wireless connections including any of the various 802.11 standards, cellular WAN infrastructures such as 3G, 4G/LTE, or 5G networks, Bluetooth®, Bluetooth® Low Energy (BLE) or Zigbee® communication links, or any other method by which one electronic device is capable of communicating with another. In some embodiments, elements of the networked portion of the invention may be implemented over a Virtual Private Network (VPN).

[0138] FIG. 30 and the following discussion are intended to provide a brief, general description of a suitable computing environment in which the invention may be implemented. While the invention is described above in the general context of program modules that execute in conjunction with an application program that runs on an operating system on a computer, those skilled in the art will recognize that the invention may also be implemented in combination with other program modules.

[0139] Generally, program modules include routines, programs, components, data structures, and other types of structures that perform particular tasks or implement particular abstract data types. Moreover, those skilled in the art will appreciate that the invention may be practiced with other computer system configurations, including hand-held devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, and the like. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

[0140] FIG. 30 depicts an illustrative computer architecture for a computer 2700 for practicing the various embodiments of the invention. The computer architecture shown in FIG. 30 illustrates a conventional personal computer, including a central processing unit 2750 ("CPU"), a system memory 2705, including a random-access memory 2710 ("RAM") and a readonly memory ("ROM") 2715, and a system bus 2735 that couples the system memory 2705 to the CPU 2750. A basic input/output system containing the basic routines that help to transfer information between elements within the computer, such as during startup, is stored in the ROM 2715. The computer 2700 further includes a storage device 2720 for storing an operating system 2725, application/program 2730, and data. [0141] The storage device 2720 is connected to the CPU 2750 through a storage controller (not shown) connected to the bus 2735. The storage device 2720 and its associated computer- readable media, provide non-volatile storage for the computer 2700. Although the description of computer-readable media contained herein refers to a storage device, such as a hard disk or CD-ROM drive, it should be appreciated by those skilled in the art that computer-readable media can be any available media that can be accessed by the computer 2700.

[0142] By way of example, and not to be limiting, computer-readable media may comprise computer storage media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other solid state memory technology, CD-ROM, DVD, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the computer.

[0143] According to various embodiments of the invention, the computer 2700 may operate in a networked environment using logical connections to remote computers through a network 2740, such as TCP/IP network such as the Internet or an intranet. The computer 2700 may connect to the network 2740 through a network interface unit 2745 connected to the bus 2735. It should be appreciated that the network interface unit 2745 may also be utilized to connect to other types of networks and remote computer systems. [0144] The computer 2700 may also include an input/output controller 2755 for receiving and processing input from a number of input/output devices 2760, including a keyboard, a mouse, a touchscreen, a camera, a microphone, a controller, a joystick, or other type of input device. Similarly, the input/output controller 2755 may provide output to a display screen, a printer, a speaker, or other type of output device. The computer 2700 can connect to the input/output device 2760 via a wired connection including, but not limited to, fiber optic, ethernet, or copper wire or wireless means including, but not limited to, Bluetooth, Near-Field Communication (NFC), infrared, or other suitable wired or wireless connections.

[0145] As mentioned briefly above, a number of program modules and data files may be stored in the storage device 2720 and RAM 2710 of the computer 2700, including an operating system 2725 suitable for controlling the operation of a networked computer. The storage device 2720 and RAM 2710 may also store one or more applications/programs 2730. In particular, the storage device 2720 and RAM 2710 may store an application/program 2730 for providing a variety of functionalities to a user. For instance, the application/program 2730 may comprise many types of programs such as a word processing application, a spreadsheet application, a desktop publishing application, a database application, a gaming application, internet browsing application, electronic mail application, messaging application, and the like. According to an embodiment of the present invention, the application/program 2730 comprises a multiple functionality software application for providing word processing functionality, slide presentation functionality, spreadsheet functionality, database functionality and the like. [0146] The computer 2700 in some embodiments can include a variety of sensors 2765 for monitoring the environment surrounding and the environment internal to the computer 2700.

These sensors 2765 can include a Global Positioning System (GPS) sensor, a photosensitive sensor, a gyroscope, a magnetometer, thermometer, a proximity sensor, an accelerometer, a microphone, biometric sensor, barometer, humidity sensor, radiation sensor, or any other suitable sensor.

[0147] The following publications are each hereby incorporated herein by reference in their entirety:

[0148] Ahmadvand S, et al. Rate and Risk Factors of Early Ventriculoperitoneal Shunt Revision: A Five-Year Retrospective Analysis of a Referral Center. World Neurosurg.

2020;134:e505-e511. doi:10.1016/j.wneu.2019.10.108

[0149] Sood S, Canady Al, Ham SD. Evaluation of Shunt Malfunction Using Shunt Site Reservoir. Pediatr Neurosurg. 2000;32(4):180-186. doi:10.1159/000028931

[0150] Paff M, et al., Ventriculoperitoneal shunt complications: A review. Interdisciplinary Neurosurgery. 2018;13:66-70. doi:10.1016/j.inat.2018.04.004

[0151] Desai VR, Sadrameli SS, Jenson A V., et al. Ventriculoperitoneal shunt complications in an adult population: A comparison of various shunt designs to prevent overdrainage. Surg Neurol Int. 2020;ll:269. doi:10.25259/SNI_38_2020

[0152] Hara M, et al., A new method for measuring cerebrospinal fluid flow in shunts. J

Neurosurg. 1983;58(4):557-561. doi:10.3171/JNS.1983.58.4.0557 [0153] Numoto M, et al., A non-invasive CSF flowmeter. J Med Eng Technol. 1984;8(5):218- 220. doi:10.3109/03091908409032079

[0154] Hara M, et al., A device to measure CSF flow in a shunt tube and its clinical application. No To Shinkei. 1982;34(10):947-953.

[0155] Raj R, et al. Demonstration that a new flow sensor can operate in the clinical range for cerebrospinal fluid flow. Sens Actuators A Phys. 2015;234:223-231. doi:10.1016/J.SNA.2015.08.023

[0156] Gamero M, et al., Multimodal Sensing Capabilities for the Detection of Shunt Failure. Sensors (Basel). 2021;21(5):l-ll. doi:10.3390/S21051747

[0157] Kim BJ, Jin W, Baldwin A, et al. Parylene MEMS patency sensor for assessment of hydrocephalus shunt obstruction. Biomed Microdevices. 2016;18(5). doi:10.1007/S10544-016- 0112-9

[0158] Basati S, et al., Impedance Changes Indicate Proximal Ventriculoperitoneal Shunt Obstruction. IEEE Trans Biomed Eng. 2015;62(12):2787-2793. doi:10.1109/TBME.2014.2335171

[0159] Krishnan SR, Arafa HM, Kwon K, et al. Continuous, noninvasive wireless monitoring of flow of cerebrospinal fluid through shunts in patients with hydrocephalus. NPJ Digit Med.

2020;3(l). doi:10.1038/S41746-020-0239-1

[0160] Qin C, Stamos B, Dasgupta PK. Inline Shunt Flow Monitor for Hydrocephalus. Anal

Chem. 2017;89(15):8170-8176. doi:10.1021/ACS.ANALCHEM.7B02034 [0161] Qin C, et al., Inline flow sensor for ventriculoperitoneal shunts: Experimental evaluation in swine. Med Eng Phys. 2019;67:66-72. doi:10.1016/J.MEDENGPHY.2019.03.010

[0162] Bork T, Hogg A, Lempen M, et al. Development and in-vitro characterization of an implantable flow sensing transducer for hydrocephalus. Biomed Microdevices. 2010;12(4):607- 618. doi:10.1007/S10544-010-9413-6

[0163] Hudson T, et al., Testing a Multi-Sensor System For Hydrocephalus Monitoring in External Ventricular Drains. In: 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII).

IEEE; 2019:310-313. doi:10.1109/TRANSDUCERS.2019.8808653

[0164] EcoCyte Bioscience Cell & Tissue Media. Accessed July 29, 2023. https://ecocyte- us.com/products/cell-tissue-media/

[0165] CODMAN® CERTAS® Plus Programmable Valve. Accessed July 29, 2023. https://www.integralife.com/codman-certas-plus-programmable- valve/product/hydrocephalus-programmable-valves-codman-certas-plus-programmable-valve

[0166] Syringe Pump - Advanced Precision Programmable Syringe Pumps - SyringePump.com. Accessed July 29, 2023. https://www.syringepump.com/NE-1000.php

[0167] ATMEGA328P | Microchip Technology. Accessed July 29, 2023. https://www.microchip.eom/en-us/product/atmega328p#document-table

[0168] ADS1256 data sheet, product information and support | Tl.com. Accessed July 29,

2023. https://www.ti.com/product/ADS1256 [0169] CGOLDENWALL Precision Scale O.lmg Analytical Balance 0.0001g Digital Scale Lab

Balance Electronic Balance for Laboratories (220g, O.lmg) : Industrial & Scientific. Accessed July 29, 2023. https://www.amazon.com/CGOLDENWALL-Precision-Analytical-Electronic-

Laboratories/dp/B08MKVPVGR?ref_=ast_sto_dp&th=l

[0170] Kadowaki C, et aL, CSF shunt physics: factors influencing inshunt CSF flow. Childs Nerv Syst. 1995;ll(4):203-206. doi:10.1007/BF00277654

[0171] 'Flowers P 'Robinson, W 'Langley R 'Theopold, K. Chemistry. In: Chemistry. OpenStax; 2015.

[0172] Ventriculoperitoneal Shunt - StatPearls - NCBI Bookshelf. Accessed July 29, 2023. https://www.ncbi.nlm.nih.gov/books/NBK459351/

[0173] Ellioun K, Yazdian F, Nouri PMM. Corrosion Resistance of Gold and Gold Oxide Nanomaterials. Smart Anticorrosive Materials: Trends and Opportunities. Published online January 1, 2023:213-228. doi:10.1016/B978-0-323-95158-6.00010-2

[0174] Fateh A, Aliofkhazraei M, Rezvanian AR. Review of corrosive environments for copper and its corrosion inhibitors. Arabian Journal of Chemistry. 2020;13(l):481-544. doi:10.1016/J.ARABJC.2017.05.021

[0175] The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. While this invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of this invention may be devised by others skilled in the art without departing from the true spirit and scope of the invention.

Claims

What is claimed is:

1. A ventriculoperitoneal (VP) shunt device, comprising: a ventricular catheter; a drainage catheter; a flow control valve fluidly connecting the ventricular catheter to the drainage catheter; and one or more capacitive or resistive flow sensors positioned at one or more positions of a fluid flow path comprising the ventricular catheter, the flow control valve, and the drainage catheter.

2. The device of claim 1, wherein the one or more capacitive or resistive flow sensors are configured to measure a fluid flow rate via a variation in charge density within the fluid.

3. The device of claim 2, wherein the fluid comprises cerebrospinal fluid (CSF).

4. The device of claim 1, wherein the one or more capacitive or resistive flow sensors each comprise: one or more emitter electrodes; one or more detector electrodes; and a voltage source electrically connected to at least one of the one or more emitter electrodes and the one or more detector electrodes.

5. The device of claim 4, wherein the distance between the one or more emitter electrodes and one or more detector electrodes is in the range of 1 mm to 1000 mm.

6. The device of claim 4, wherein the one or more emitter electrodes and one or more detector electrodes each have lengths in the range of 0.1 mm to 50 mm, widths in the range of 0.1 mm to 1 mm, and thicknesses in the range of 0.1 mm to 1 mm.

7. The device of claim 4, wherein the one or more emitter electrodes and one or more detector electrodes each have lengths of 3 mm, widths of 0.4 mm, and thicknesses of 0.4 mm.

8. The device of claim 4, wherein the one or more emitter electrodes and one or more detector electrodes each comprise at least one of gold, silver, copper, titanium, steel, or nitinol.

9. The device of claim 4, wherein the one or more emitter electrodes and one or more detector electrodes are each at least partially formed in one or more shapes.

10. The device of claim 9, wherein the one or more shapes are selected from: wire, cylinder, hollow cylinder, ring, torus, annulus, cube, prism, a rectangular prism, a sphere, curvilinear, bowed, curved, helix, double-helix, or spiral.

11. The device of claim 1, further comprising: an analog-to-digital converter (ADC) communicatively connected to the one or more capacitive or resistive flow sensors; and a microcontroller communicatively connected to the ADC.

12. The device of claim 1, wherein the one or more positions are associated with the ventricular catheter and comprise at least one of: a first end of the ventricular catheter; a tip of the ventricular catheter; a position along the length of the ventricular catheter; a second end of the ventricular catheter proximate to the flow control valve; between and inline with the ventricular catheter and the flow control valve; surrounding either partially or entirely at least a portion of the ventricular catheter; within the walls of the ventricular catheter either partially or entirely; within a cavity of the ventricular catheter; and within a lumen of the ventricular catheter.

13. The device of claim 1, wherein the one or more positions are associated with the flow control valve and comprise at least one of: surrounding either partially or entirely at least a portion of flow control valve; within the body of the flow control valve either partially or entirely; and within a cavity of the flow control valve.

14. The device of claim 1, wherein the one or more positions are associated with the drainage catheter and comprise at least one of: between and inline with the flow control valve and the drainage catheter; a first end of the drainage catheter proximate to the flow control valve; a position along the length of the drainage catheter; a second end (i.e. tip) of the drainage catheter; a tip of the drainage catheter; surrounding either partially or entirely at least a portion of the drainage catheter; within the walls of the drainage catheter either partially or entirely; within a cavity of drainage catheter; and within a lumen of drainage catheter.

15. The device of claim 1, wherein the one or more capacitive or resistive flow sensors are configured to detect fluid flow rates in the range of 0.01 mL/min to 0.9 mL/min.

16. A ventriculoperitoneal (VP) shunt system, comprising: a VP shunt device comprising: a ventricular catheter; a drainage catheter; a flow control valve fluidly connecting the ventricular catheter to the drainage catheter; and one or more capacitive or resistive flow sensors positioned at one or more positions of a fluid flow path comprising the ventricular catheter, the flow control valve, and the drainage catheter; and a computing system communicatively connected to the VP shunt device, comprising a processor and a non-transitory computer-readable medium with instructions stored thereon, which when executed by the processor, perform steps comprising: calculating at least one of a flow rate, a flow acceleration, and a valve state by measuring properties of the fluid with the one or more capacitive or resistive flow sensors; identifying failure of or blockage of the VP shunt device based on at least one of the flow rate, flow acceleration, and valve state; and providing an alert when failure of or blockage of the VP shunt device is identified.

17. The system of claim 16, wherein the computing system is communicatively connected to the VP shunt device via a wireless communication protocol comprising at least one of a

802.11 standard, cellular WAN infrastructure, Bluetooth, Bluetooth Low Energy (BLE) Zigbee, Near-Field Communication (NFC), and infrared.

18. The system of claim 16, wherein the processor of the computing system is configured to calculate fluid flow rate by performing steps comprising: applying a voltage for a period of time via one or more emitter electrodes of the one or more capacitive or resistive flow sensors to modify the charge density within a portion of a fluid in the VP shunt system; detecting the portion of the fluid with the modified charge density via one or more detector electrodes of the one or more capacitive or resistive flow sensors; measuring a time difference between applying the voltage via the one or more emitter electrodes and detecting the portion of the fluid with the modified charge density via one or more detector electrodes based on the detected response; and calculating a fluid flow rate based on the measured time difference and known distance between the one or more emitter electrodes and the one or more detector electrodes.

19. The system of claim 16, wherein the processor of the computing system is configured to calculate fluid acceleration by performing steps comprising: measuring a change in capacitance due to variation in a dielectric value of a fluid moving in the system; and calculating a flow acceleration based on the change in capacitance.

20. The system of claim 16, wherein the processor of the computing system is configured to measure valve state by performing steps comprising: measuring a change in capacitance or resistance due to variation in a dielectric value or electrical resistance of a fluid moving in the system; and determining the valve state by determining the geometry of the dielectric fluid before and after the valve.

21. A method for identifying failure or blockage in a ventriculoperitoneal (VP) shunt, comprising: providing a VP shunt system of claim 16; calculating at least one of a flow rate, a flow acceleration, and a valve state by measuring properties of the fluid with the one or more capacitive or resistive flow sensors; identifying failure of or blockage of the VP shunt device based on at least one of the flow rate, flow acceleration, and valve state; and providing an alert when failure of or blockage of the VP shunt device is identified.

22. The method of claim 21, wherein the method is configured to identify failure or blockage in a VP shunt configured to accommodate fluid flow rates in the range of 0.01 mL/min to 0.9 mL/min.