WO2012155157A1 - Capteur capacitif de support multiple - Google Patents

Capteur capacitif de support multiple Download PDF

Info

Publication number
WO2012155157A1
WO2012155157A1 PCT/ZA2012/000027 ZA2012000027W WO2012155157A1 WO 2012155157 A1 WO2012155157 A1 WO 2012155157A1 ZA 2012000027 W ZA2012000027 W ZA 2012000027W WO 2012155157 A1 WO2012155157 A1 WO 2012155157A1
Authority
WO
WIPO (PCT)
Prior art keywords
transducer
module
capacitance
electrodes
motion
Prior art date
Application number
PCT/ZA2012/000027
Other languages
English (en)
Inventor
Frederick Johannes Bruwer
Daniël Barend RADEMEYER
Original Assignee
Azoteq (Pty) Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Azoteq (Pty) Ltd filed Critical Azoteq (Pty) Ltd
Publication of WO2012155157A1 publication Critical patent/WO2012155157A1/fr

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6813—Specially adapted to be attached to a specific body part
    • A61B5/6824—Arm or wrist
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
    • A61B5/02438—Detecting, measuring or recording pulse rate or heart rate with portable devices, e.g. worn by the patient
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
    • A61B5/02444—Details of sensor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/683—Means for maintaining contact with the body
    • A61B5/6831—Straps, bands or harnesses
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6887—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient mounted on external non-worn devices, e.g. non-medical devices
    • A61B5/6898—Portable consumer electronic devices, e.g. music players, telephones, tablet computers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
    • A61B2562/0204—Acoustic sensors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
    • A61B2562/0209—Special features of electrodes classified in A61B5/24, A61B5/25, A61B5/283, A61B5/291, A61B5/296, A61B5/053
    • A61B2562/0214—Capacitive electrodes

Definitions

  • the invention pertains to the use of a range of transducers in conjunction with, and external to, a capacitive sensing IC (integrated circuit) to sense motion in multiple media by measuring capacitance variance.
  • Capacitive motion sensing using MEMS devices is a well-researched and commercially developed field.
  • a fair amount of integrated circuits exist that can measure motion in one to three dimensions.
  • the cost of the devices still prohibits deployment in applications that are highly cost sensitive.
  • the capacitive transducer of a MEMS device being contained within the confines of an integrated circuit housing and typically etched into a semiconductor substrate, is fixed in dimensions and composition. Adjustment of transducer characteristics to suit a specific application is not feasible. If a change in capacitance due to motion for a particular MEMS device is not sufficient in a certain application, the selection of a new integrated circuit is required.
  • motion, acceleration and tilt sensors are used in a number of high end portable electronic products, specifically smart phones. Typically, these would be used to wake a unit from a deep sleep mode as soon as the unit is moved, to orient the unit's display according the manner in which it is held, and to record motion and shock, either for protection or gaming purposes.
  • lower end portable electronics of the present state of the art seldom utilize any motion sensors, as the cost and power consumption thereof prohibit it.
  • Electrodes which make galvanic contact with a user's skin conduct an electrical signal present on the skin to an amplification circuit.
  • an infrared LED and sensor are used to detect a light permeability change due to blood being pumped rhythmically by the heart. This change in infrared light permeability is typically measured on the tip of a finger, or on an earlobe.
  • the infrared technique requires the subject to stay fairly immobile and, as such, it is not generally practical for sport applications.
  • the disclosed invention constitutes a low-cost motion detector based on capacitive sensing. Its main characteristic is the fact that all the capacitive transducers utilized are non-MEMS and external to an integrated circuit which measures the change in capacitance.
  • transducer includes a complete assembly used to convert a motion into a capacitance change, and comprises electrodes, dielectric material, interconnects and other structural elements. The aforementioned main characteristic makes it possible to detect motion in a cost-effective manner in three of the four material states i.e. in gasses, liquids and solid materials. It also enables the possible adjustment of transducer dimensions or composition to suit a specific application, without the need to change the integrated circuit.
  • the digital output of the capacitive sensing IC should be proportional to the amplitude of the sound waves.
  • Motion detection according to the present invention with an electret film as a transducer is not restricted to air alone. Given the typical thickness of an electret film available commercially, motion detection could be feasible in other gasses or in liquids by placing the film within the medium, or with one surface of the electret film touching the medium, and thus exposed to motion and pressure changes. If motion in a solid material needs to be detected, the film could be attached along a periphery of the film to the solid material. Due to the difference in inertias of the film and of the solid material, motion changes should cause film deflection, which may be measured as a change in capacitance.
  • a biasing and transistor circuit may also be feasible to use a biasing and transistor circuit to amplify the voltage signal obtained due to motion of an electret film, contained in, or attached to, a liquid, gaseous or solid body, and measure this signal directly with a capacitive sensing IC.
  • a number of filtering techniques may also be applied to the signal before using it to inject charge into the capacitive sensing IC. For instance, if a periodic signal such as human heart rate, or engine combustion cycle, a filter with a relevant pass band centred on the expected periodic frequency may be employed. Or, if the intention is to measure shock impulses, for instance during fragile goods transport, a peak detector may be employed to capture the highest motional amplitude experienced.
  • the present invention allows the manner in which the electrodes are kept in place in the vicinity of the heart-rate based deflecting skin section to be quite varied. For instance, skin motion due to heart rate may be measured at a user's finger through the use of a ring-like device to keep the electrodes in place. Or the electrodes may be inserted underneath a wristband of an athlete's watch. The number of electrodes also do not have to be constrained to two, but multiple pairs may be used.
  • multiple pairs of electrodes may be incorporated into the material of a sports watch strap, thereby reducing the sensitivity to electrode position of the heart rate monitoring system.
  • a method of using a volume charged, void-filled electret material such as that marketed under the name EMFIT, to measure human heart rate with a single capacitance sensing IC. If the capacitive heart rate transducers are incorporated into the structure of a sports watch, be it in the strap or the watch body, a self-contained unit is formed, without the need to transmit the heart rate data to the watch via an air interface, as is presently done with chest-strap based heart rate monitors.
  • Another embodiment of the present invention for the detection of human heart rate teaches the use of a semi-rigid strap to be placed securely around a user's wrist.
  • Pliable, conductive material is situated between the user's wrist and the semirigid strap, separated from the strap by a compressible dielectric material, which may be air.
  • the conductive material is electrically floating relative to the measurement circuitry which is employed, or it may be grounded.
  • a number of electrodes are placed on the semi-rigid strap, in close proximity to the pliable conductive material which is situated against the user's skin. When the user's skin moves due to heart rate, the pliable conductive material moves toward and away from the electrodes.
  • This may be measured as a proportional change in capacitance between two specific electrodes (mutual), or between an electrode and earth (self-capacitance).
  • an electret microphone with integral transistor amplification, as discussed above, is used in conjunction with a first air cavity and a flexible membrane to detect human heart rate.
  • the first air cavity is covered by the flexible membrane, with the membrane placed on the user's skin, in an area where heart action typically results in skin motion.
  • the first air cavity is sealed, except for a small channel or pipe, with a diameter substantially less than the dimensions of the first air cavity, leading from one wall or side of the cavity.
  • the distant end of the channel or pipe opens to a second sealed cavity which contains the electret microphone.
  • the electret microphone is positioned in such a manner that its electret membrane is maximally exposed to the channel or pipe, in terms of air or gas flow.
  • the air or gas in the first cavity is compressed, and along with it the air or gas in the channel or pipe. This results in air or gas movement against the electret membrane of the microphone. Due to the significant smaller dimensions of the channel or pipe, the air or gas movement in the first cavity is amplified, resulting in increased movement of the electret membrane compared to what would be obtained if the microphone were to be placed directly into the first air cavity. This increase in movement typically results in a larger signal from an electret microphone and capacitive sensing combination, as disclosed above. Therefore, it may be used to detect a heart rate with more fidelity than what would be obtained otherwise.
  • Measurement of heart rate according to the present invention may be implemented in a completely waterproof manner.
  • the electrodes do not have to be in galvanic contact with the user's skin, but only mechanically connected to it, waterproofing may be realized in a cost effective manner.
  • the waterproof nature could potentially pose a significant advantage in many sports applications, especially if combined with the inherent cost-effectiveness of the present invention.
  • one or more transducers may be placed around any limb or the user, or any other body part, as required.
  • Tilting motion of devices may also be accurately measured according to the present invention.
  • a capacitance sensing IC in conjunction with a number of transducer components, such as springs, flexible membranes, rolling balls or contained liquid bodies, it may be possible to measure tilt. For instance, by attaching an electrode to a spring which is anchored to the body being tilted, a change in either mutual or self-capacitance may be measured which should be proportional to tilt.
  • tilting motion may be measured in 2 dimensions. If track is kept of tilting progression, it might further be possible to determine not only tilt, but also which side is up. If tilting motion along a specific axis only needs to be measured, it may be possible to use flexible membranes, such as a flexible printed circuit, or FPC, in the above manner. Flexible membranes tend to be fairly stiff in movement parallel to their surface area, and only bend perpendicular to it, making them ideal for constrained tilting measurement.
  • Another embodiment of the present invention would be to use a rolling ball to detect tilting motion.
  • a rolling ball may be used in various ways with a capacitive sensing IC to measure tilt. For instance, if a metal ball is rolled by tilting motion along a predetermined, constrained track, with electrodes placed in a chosen location alongside the track, a measureable change in capacitance might be realized. As the metal ball rolls closer to or further from the electrodes, it should perturb the electrical coupling between the electrodes. In a mutual capacitance arrangement, one electrode may be a transmit electrode, and another electrode may be a sense electrode. As the ball rolls closer to the electrodes, less charge should be transferred between the transmit and sense electrodes, which should result in a decrease in measured capacitance.
  • a spherical vessel may be used to contain the rolling ball, with a plurality of electrodes which may be placed around a periphery of the sphere, !n this manner, a more exact value of the tilt angle should be discernible, and clicking sounds due to host tilting should not be evident. However, if the sphere is shaken or vibrated, clicking sounds might still be heard. Further, due to the solid nature of the ball and the requirement that it rolls fairly freely, with sufficient spacing to a minimum number of electrodes inside the sphere, its maximum diameter is limited, and it will typically not easily give an exact angle of tilt.
  • the use of a ionic, liquid body instead of a rolling ball allows a more exact measurement of the tilting angle of the hosting device.
  • the movement of the liquid body to and from electrodes should be much more continuous, and the liquid should mate perfectly with boundaries of the vessel containing the liquid, ensuring the biggest effect on electric fields emanating from the electrodes. Further, it should ensure a silent, cost effective tilt sensor without any clicking sounds.
  • the fluid (liquid) used needs to contain enough ions to disrupt the nominal electric field lines between electrodes. And for applications in the region of, or below zero degrees Celsius, the fluid type will have to be carefully chosen to ensure it does not freeze, or lose its viscosity in a substantial manner.
  • the signals from capacitive tilting motion sensors as described above should be static or quasi-static in nature, and should need little filtering if the hosting device is tilted only.
  • normal use may typically include motion which is acceleratory or vibratory in nature.
  • a filter producing the envelope of the measured capacitance related signal might be required. Should the capacitance be stable at a certain new value for a minimum period, a tilt can be annunciated.
  • non-MEMS sensors which can measure acceleration or vibration.
  • the above mentioned embodiments of the present invention that utilize springs or flexible membranes as part of the required capacitive transducers may be used to measure such motion.
  • an output signal from a capacitive sensing IC should typically be decaying and oscillatory. Therefore, if the signal is filtered correctly to determine its primary peak value, the period at which this peak is maintained, and its decay period, a fair amount of information about the acceleratory motion can be garnered.
  • vibratory motion should produce a static or quasi-static envelope signal which, if filtered correctly, may be used to identify vibration, using a spring or flexible spring-based transducer and a separate capacitive sensing IC.
  • the invention provides a module comprising a capacitive measurement integrated circuit coupled with at least one capacitance transducer for use in a product, wherein said at least one transducer is located external to the integrated circuit, with said integrated circuit controlling and performing a charge transfer capacitance measurement process, said module characterized by at least one transducer designed to be positioned on or around limbs or body parts to facilitate the measurement of a heart rate.
  • the product may be a heart rate monitor wherein the transducer detects motion due to a variation in blood pressure during a heartbeat cycle.
  • the transducer may make use of a compressible dielectric material, said dielectric material separating a plurality of electrodes used for capacitive sensing, and wherein at least one of the electrodes is fairly static relative to the movement of a user's skin, or of a volume charged, void-filled, electret material, said electret material being compressible, and placed against a user's skin, with skin motion causing capacitance changes according to the material properties of said electret material.
  • At least one layer of conductive material may be positioned on an outside of the transducer construction in order to help shield electrodes of the transducer from causes of noise.
  • Figure 1 shows an exemplary embodiment of the present invention which detects motion in air, typically due, but not limited to, audible sound, through the use of inexpensive electret film technology;
  • Figure 2 shows an exemplary embodiment of the present invention which can detect motion of human skin, typically caused by but not limited to, a pulse or heart rate;
  • Figure 3 shows an exemplary embodiment of the present invention which can detect tilting motion of a device;
  • Figure 4 shows an exemplary embodiment of the present invention which can detect, but not limited to, vibratory or accelerative motion of a device in one or two dimensions;
  • Figure 5 illustrates an exemplary implementation of a tilt/vibration/rnovement transducer according to the present invention, that utilizes, but which is not limited to, a mm scale spring attached to an electrode;
  • Figure 6 illustrates an exemplary implementation of a 2.5D motion transducer according to the present invention, that utilizes, but which is not limited to, a ring of 4 electrodes surrounding a mm scale spring attached to an electrode;
  • Figure 7 illustrates an exemplary implementation of a transducer for skin motion, according to the present invention, that utilizes, but which is not limited to, two rigid electrodes separated by a compressible medium;
  • Figure 8 illustrates an exemplary implementation of a transducer that can detect either tilting, vibratory or accelerative motion according to the present invention, utilizing, but not limited to, a rolling ball, constrained to a predetermined track and space, which perturbs electric fields surrounding a set of electrodes;
  • Figure 9 illustrates an exemplary implementation of a transducer that can detect tilting, vibratory or accelerative motion by containing an electric field disrupting object, typically a metal ball or a small amount of liquid, within a volume, typically a sphere or cylinder, with electrodes on a periphery of the volume to measure corresponding changes in capacitance,
  • an electric field disrupting object typically a metal ball or a small amount of liquid
  • Figure 10 illustrates an exemplary implementation of a motion transducer according to the present invention, which utilizes, but which is not limited to, a low cost flexible printed circuit (FPC) material to realize deflecting beam and capacitive sensing electrodes;
  • Figure 11 (A) illustrates details of an exemplary biasing circuit for the sound sensor of FIG. 1 ;
  • Figure 1 1 (B) illustrates an exemplary embodiment of the present invention to detect motion in liquids, gasses or solid bodies through the use of an electret film and a biasing and amplification circuit used to inject charge directly into a capacitive sensing IC;
  • Figure 1 (C) illustrates an exemplary embodiment of the present invention similar to that of Figure 1 (B), but with the addition of a peak detector to capture a signal corresponding to the maximum motion experienced by an electret film transducer;
  • Figure 12 illustrates an exemplary embodiment of a capacitive heart rate sensor attached to an inner surface of a watch wristband;
  • Figure 13 illustrates yet another exemplary embodiment of a capacitive heart rate sensor that employs deformable cells within the wristband of a watch, with electrodes contained within each cell to measure corresponding changes in capacitance;
  • Figure 14 illustrates an exemplary embodiment of a capacitive heart rate transducer in the form of an adjustable ring, to be placed around a user's finger;
  • Figure 15 illustrates an exemplary embodiment that utilizes a semi-rigid strap around a user's wrist, in conjunction with pliable conductive material, and a plurality of electrodes to detect human heart rate.
  • the combination of electret film and capacitive sensing technology offers the possibility to realize motion detection in three of the four material states that is in gaseous substances, liquids and in solid materials.
  • a change in capacitance occurs.
  • the change in capacitance is accompanied by a voltage change.
  • a capacitive sensing IC 10 may be used to detect the change in capacitance due to film motion directly, or the voltage change Vs may be measured by the same IC, using a simplistic biasing circuit 12.
  • sound may be detected accurately through a combination of an electret film and a capacitive sensing IC.
  • Propagating air waves carry the sound, and also deflect the electret film inwards and outwards, resulting in a changing voltage / capacitance, which could be measured by the capacitive sensing IC.
  • Another embodiment would be to use an extremely low cost electret microphone 13 as a transducer. These microphones are very commonplace, and are used in a wide range of consumer electronic products, such as mobile telephones, headsets for personal computer use, fixed telephones etc.
  • a biasing circuit 14 may be utilized, as depicted in exemplary manner in Figure 11(A), to bias a JFET 16 typically contained within this type of low cost electret microphone. Once biased correctly, the voltage from the JFET may be used to drive a sensing pin 18 of a capacitive sensing IC, as depicted in Figure (A), with the driving current typically proportional to the amplitude of the sound waves incident on the microphone.
  • a transmit pin 20 of the capacitive sensing IC is typically utilized to energize the final stage of the biasing circuit depicted in Figure 1 (A), and to charge a fixed capacitance C2 between the transmit and sense pins, resulting in a more stable signal. This final stage biasing method should reduce current consumption significantly, since energy is only dissipated when the transmit pin is driven high.
  • Figure 1 1 (B) presents another exemplary embodiment to detect motion using an electret film as a transducer 24 in conjunction with an FET, or an alternative switching element, -based amplification 26, and a biasing circuit 28 to inject charge directly into a capacitive sensing IC 30.
  • the capacitance between electrodes 32 and 34 should be directly proportional to the charge contained within an electret film 36 and the spacing 38 between the film 36 and the electrode 34. If either the film or the opposite electrode moves closer to or further from the other electrode, due to motion of the hosting liquid, gas or solid material, the capacitance should increase or decrease respectively.
  • Typical values which may be practically realized are in the order of 30pF for the spacing 38 at its maximum, and 15pF for the spacing at its minimum.
  • the change in capacitance should also imply a proportional change in voltage across the electrodes 32 and 34.
  • This voltage may be applied to a terminal 42 of the FET amplification circuit 26.
  • the output of the amplification circuit may be used as an input to the biasing circuit 28, at a terminal 44.
  • the voltage signal due to the motion of the liquid, gaseous or solid material body hosting the electret film may be used to inject charge directly into the capacitive sensing IC 30, resulting in a digital signal which is directly proportional to host motion.
  • a diode 46 typically serves dual functions.
  • FIG. 11 Various filtering circuits may be applied to the embodiment in Figure 11 (B) to detect certain categories of motion.
  • the output of an amplification and biasing circuit 50, at a terminal 52 is applied to a peak detection circuit 54, before being used to inject charge into a capacitive sensing IC 56.
  • a peak detection circuit- based embodiment may be used to detect shock of a device in a cost-effective, flexible and reliable manner.
  • a band pass filter circuit may be used, with a pass band from 0.4HZ to 5Hz, to detect human heart rate due to motion of the skin.
  • the same capacitive sensing IC may be used in conjunction with a transducer 60, of the kind shown in Figure 7, to accurately detect skin motion caused by a pulse / heart rate.
  • a transducer 60 of the kind shown in Figure 7, to accurately detect skin motion caused by a pulse / heart rate.
  • the deflection of the skin 64 due to pulse rate may be measured accurately using a mutual capacitance sensing IC 56.
  • FIG. 13 Another embodiment, depicted in Figure 13, utilizes a plurality of sensor cells 86, incorporated directly into the material of a wristband 88 of a watch 90.
  • the cells are separated by walls, with each cell constituting a self-contained skin deflection device, and therefore heart-rate, monitoring unit.
  • Figure 13(A) shows, on an enlarged scale, a cell 86 which contains two electrodes 92 and 94, separated by a compressible dielectric medium 96, which may or may not be of similar material as the cell material 98, which contains the whole assembly. It also falls within the scope of the present invention, to use a compressible liquid or gel for the dielectric medium 96 or cell material 98.
  • the electrodes 92 and 94 may form part of a mutual capacitance sensing circuit. As the skin expands due to a heart rate variation, it should push the electrode 94 closer to the electrode 92, resulting in a capacitance increase, which could be measured by a capacitive sensing IC contained within the watch 90. As stated before, through the use of multiple cells within the wristband of the watch, the challenge of placing the heart rate transducer on an exact area of skin to obtain a highest signal to noise ratio may be overcome. Capacitance measurements from multiple cells may be compared with an expected waveform to determine which cell is most optimally placed, and then use the information from that cell to determine the heart rate.
  • an adjustable ring 102 containing one or a plurality of capacitive heart rate sensors 104 according to the invention are placed on a person's finger. A user may adjust the ring with swing arms 106 and VelcroTM straps 108, thus compressing the skin, until his/her pulse is sensed reliably.
  • a body of the ring 102 may contain a battery supply and an extremely low power wireless link, making the ring completely self-contained and free of encumbering wires.
  • FIG. 15 depicts yet another exemplary embodiment of the present invention.
  • a semi-rigid strap 110 is placed around a user's wrist, and secured and tightened by straps 112 and 1 14.
  • these straps may be formed from VelcroTM.
  • a pliable conductive strip 16 is used on an inner side of the strap 1 10. This conductive strip is therefore placed against the user's skin.
  • a plurality of electrodes 118 is located on an inner face of the semi-rigid strap 1 10. These electrodes may be used for self-capacitance or mutual-capacitance measurements, used to determine the user's heart rate.
  • a thin layer of compressible dielectric material 122 separates the pliable conductive material 1 16 and the semi-rigid strap 110.
  • the pliable conductive material 6 floats electrically relative to the capacitive measurement circuit, or it may be grounded. As the user's skin moves due to his or her heart rate variation, the pliable conductive material 116 is moved closer to or further from the electrodes 118, resulting in a change in the measured capacitance, be that self- or mutual capacitance.
  • the present invention teaches that it may be possible to obtain an accurate indication of the user's heart rate without the measurement being overly dependent on the exact placement and location of the whole assembly on the user's wrist.
  • FIGs 3 and 4 illustrate in exemplary manner that the capacitive sensing IC 56 may also be used to detect tilting, accelerative or vibratory motion in a solid medium, such as spring steel or a flexible printed circuit board (FPC), using the correct transducers.
  • a solid medium such as spring steel or a flexible printed circuit board (FPC)
  • FPC flexible printed circuit board
  • a transducer 130 is shown that may be used to detect vibratory, accelerative or tilting motion in one or two dimensions.
  • An electrode 132 is attached to a flexible medium 134, which may be a small spring.
  • the combination of the flexible medium and the electrode is anchored at a location 136, which will typically be the hosting device. Electrodes 138 and 140 will typically be below the electrode
  • the electrode 132 should swing from a centre point between the electrodes 138 and 140.
  • the electrode 132 should either move closer to the electrode 138 or 140, or move closer to or further from both, depending on the direction of the motion.
  • the movement may be detected through mutual or self-capacitance sensing.
  • mutual capacitance By making the electrode 132 a transmit or energizing electrode, and the electrodes 138 and 140, sensing electrodes of separate channels, mutual capacitance may be used to detect the motion.
  • mutual capacitance may be used to detect the motion.
  • motion may also be detected.
  • FIG. 6 presents another exemplary embodiment of a 2.5D movement sensor 144, according to the present invention.
  • an electrode 146 is attached via a flexible beam or spring 148 to a point 150 which is anchored to a host device.
  • the electrode 146 is surrounded by a ring of four electrodes 152, 154, 156 and 158.
  • Vibratory or accelerative motion may be detected in two dimensions. Tilting motion may be detected in two dimensions, being the x and y directions, and it may also be possible to monitor which side is upwards. This should be possible because the earth's gravitational force is always directed downwards, and it is not possible to obtain an upturned device without progressing through a maximum amount of tilting in a particular direction.
  • either mutual or self- capacitance sensing may be used to detect the motion of the above electrodes, and thereby, of the hosting device.
  • Figure 8 illustrates yet another exemplary embodiment of a tilt or motion sensor according to the present invention.
  • a ball 160 typically but not necessarily from metal, with a diameter typically on the mm scale, rolls along a predetermined and constrained track 162.
  • Two electrodes 164 are situated at one end of the track 162.
  • the ball may or may not make galvanic contact with the electrodes.
  • the hosting device is moved along an axis parallel to the ball track 162, the ball should roll closer to or further from the electrodes 164.
  • One possibility, according to the present invention, is to make the electrodes 164 the transmit (164A) and sense (164B) electrodes of a mutual capacitance circuit.
  • the mutual capacitance should decrease/increase accordingly, which may be measured by the IC 56 depicted in Figures 3 and 4.
  • embodiments of the present invention using a rolling ball need not be constrained to a mutual capacitance implementation. By using only one electrode at one end of the constrained rolling track for the ball, a change in self-capacitance can be effected through host device motion or tilting, which can be measured.
  • an incline 170 relative to the gravitational force of the earth, may be inserted in the constrained rolling track 162 (see Figure 8(B)). Further, to avoid the clicking sound typically experienced with rolling ball motion sensors, a curvature may be introduced into a track 172 (see Figure 8(C)). In this case, the ball will always start from the lowest point of the track, and if designed correctly, will not collide with a high impact during envisaged motion of the hosting device.
  • Another variation of the embodiment presented in Figure 8 is to use a pendulum-like transducer, which swings metal closer or further from an electrode or plurality of electrodes.
  • a sphere 174 contains a typically, but not necessarily, metallic ball 176, which can roll freely within it. Normally, the sphere would consist of insulating material.
  • a plurality of electrodes are placed on the periphery of the sphere. In the example of Figure 9, four electrodes 178, 180, 182, 184 are placed on the periphery, typically isolated by the sphere material from contact with the ball 176. As depicted in Figure 9, the ball should always ultimately reside at the point in the sphere which is closest to the earth, due to the earth's gravitational force.
  • the electrodes 178 and 184 form a transmit and sense pair of a mutual capacitance circuit, and are connected to an external capacitive sensing IC, as per the invention, it is clear from the example of Figure 9 that tilting the sphere towards the electrode 180 should result in an increased measured mutual capacitance for the electrode pair 178 and 184.
  • one or more of the plurality of electrodes on the periphery of the sphere may be tied to ground, and the self-capacitance of the remaining electrodes may be utilized to monitor tilt. In the above manners, tilting of a hosting device may be measured with the transducer of Figure 9, with a large number of electrode combinations and uses possible.
  • a spherical transducer as depicted in Figure 9, might still experience clicking sounds if the hosting device is shaken or vibrated. Due to the discrete nature of the rolling ball, it might also be difficult to obtain exact tilting angles.
  • an embodiment of the invention such as presented in Figure 9(A) may be used.
  • An ionic fluid body 190 is used in the above mentioned sphere, instead of the rolling ball 176.
  • the perturbation of the electric fields between electrode pairs should be much more gradual. This may allow for a more exact determination of the tilting angle. It should result in a silent tilt sensor according the present invention.
  • Figure 0 presents an exemplary tilting or motion transducer according to the present invention that utilizes a purely flexible printed circuit material implementation.
  • a deflecting beam 190 is punched or cut into flexible material 192, with two electrodes 194 and 196 printed with a normal flexible printed circuit deposition process.
  • the electrode 196 is placed on a T-piece that terminates the deflecting beam, and the electrode 194 is placed in a parallel position on the material 192, which is fairly static in position relative to the hosting device. If the hosting device accelerates, vibrates or tilts along an axis perpendicular to the surface of the material 192, the beam will bend, causing the electrode 196 to move further from the electrode 194.
  • a self- capacitance sensing IC can also be used to detect motion according to the exemplary embodiment of Figure 10, by connecting one electrode to ground, and sensing the change in self-capacitance of the other.
  • FIG 10(C) another typical embodiment might use rigid PCB material 200 to implement a motion/tilting sensor in a manner similar to the above.
  • a flexible printed circuit beam and T-piece similar to the above are used, but are soldered onto the rigid PCB at a location 202, and lifted by a support 204 to ensure that motion in two directions can be detected.

Abstract

La présente invention concerne un détecteur de mouvement à faible coût basé sur une détection capacitive, qui utilise des transducteurs non-MEMS, externes à un circuit intégré, pour mesurer un changement de capacité.
PCT/ZA2012/000027 2011-05-06 2012-05-04 Capteur capacitif de support multiple WO2012155157A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA201103299 2011-05-06
ZA2011/03299 2011-05-06

Publications (1)

Publication Number Publication Date
WO2012155157A1 true WO2012155157A1 (fr) 2012-11-15

Family

ID=46457103

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/ZA2012/000027 WO2012155157A1 (fr) 2011-05-06 2012-05-04 Capteur capacitif de support multiple

Country Status (1)

Country Link
WO (1) WO2012155157A1 (fr)

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103860170A (zh) * 2014-03-11 2014-06-18 天津师范大学 电导生物反馈训练仪
EP3231356A1 (fr) 2016-04-11 2017-10-18 Hill-Rom Industries SA Capteur capacitif destiné à la surveillance respiratoire
CN108882886A (zh) * 2016-03-29 2018-11-23 小利兰·斯坦福大学托管委员会 接近度传感器电路以及相关的感测方法
CN109662702A (zh) * 2018-05-23 2019-04-23 李芝宏 电容式脉搏检测系统及方法
WO2020018892A1 (fr) * 2018-07-19 2020-01-23 Ctrl-Labs Corporation Procédés et appareil pour une robustesse de signal améliorée pour un dispositif d'enregistrement neuromusculaire portable
US10656711B2 (en) 2016-07-25 2020-05-19 Facebook Technologies, Llc Methods and apparatus for inferring user intent based on neuromuscular signals
US10687759B2 (en) 2018-05-29 2020-06-23 Facebook Technologies, Llc Shielding techniques for noise reduction in surface electromyography signal measurement and related systems and methods
US10842407B2 (en) 2018-08-31 2020-11-24 Facebook Technologies, Llc Camera-guided interpretation of neuromuscular signals
CN112099669A (zh) * 2020-09-11 2020-12-18 合肥工业大学 用于腕背部手势识别的驻极体电容式压力传感器单元阵列
US10905383B2 (en) 2019-02-28 2021-02-02 Facebook Technologies, Llc Methods and apparatus for unsupervised one-shot machine learning for classification of human gestures and estimation of applied forces
US10921764B2 (en) 2018-09-26 2021-02-16 Facebook Technologies, Llc Neuromuscular control of physical objects in an environment
US10937414B2 (en) 2018-05-08 2021-03-02 Facebook Technologies, Llc Systems and methods for text input using neuromuscular information
US10970374B2 (en) 2018-06-14 2021-04-06 Facebook Technologies, Llc User identification and authentication with neuromuscular signatures
US10970936B2 (en) 2018-10-05 2021-04-06 Facebook Technologies, Llc Use of neuromuscular signals to provide enhanced interactions with physical objects in an augmented reality environment
US10990174B2 (en) 2016-07-25 2021-04-27 Facebook Technologies, Llc Methods and apparatus for predicting musculo-skeletal position information using wearable autonomous sensors
US11036302B1 (en) 2018-05-08 2021-06-15 Facebook Technologies, Llc Wearable devices and methods for improved speech recognition
US11069148B2 (en) 2018-01-25 2021-07-20 Facebook Technologies, Llc Visualization of reconstructed handstate information
US11079846B2 (en) 2013-11-12 2021-08-03 Facebook Technologies, Llc Systems, articles, and methods for capacitive electromyography sensors
US11179066B2 (en) 2018-08-13 2021-11-23 Facebook Technologies, Llc Real-time spike detection and identification
US11216069B2 (en) 2018-05-08 2022-01-04 Facebook Technologies, Llc Systems and methods for improved speech recognition using neuromuscular information
US11337652B2 (en) 2016-07-25 2022-05-24 Facebook Technologies, Llc System and method for measuring the movements of articulated rigid bodies
CN114571505A (zh) * 2022-02-28 2022-06-03 深圳市越疆科技有限公司 基于自电容检测的电子皮肤模块、机械臂和设备
US11481030B2 (en) 2019-03-29 2022-10-25 Meta Platforms Technologies, Llc Methods and apparatus for gesture detection and classification
US11481031B1 (en) 2019-04-30 2022-10-25 Meta Platforms Technologies, Llc Devices, systems, and methods for controlling computing devices via neuromuscular signals of users
US11493993B2 (en) 2019-09-04 2022-11-08 Meta Platforms Technologies, Llc Systems, methods, and interfaces for performing inputs based on neuromuscular control
US11567573B2 (en) 2018-09-20 2023-01-31 Meta Platforms Technologies, Llc Neuromuscular text entry, writing and drawing in augmented reality systems
US11635736B2 (en) 2017-10-19 2023-04-25 Meta Platforms Technologies, Llc Systems and methods for identifying biological structures associated with neuromuscular source signals
US11666264B1 (en) 2013-11-27 2023-06-06 Meta Platforms Technologies, Llc Systems, articles, and methods for electromyography sensors
US11797087B2 (en) 2018-11-27 2023-10-24 Meta Platforms Technologies, Llc Methods and apparatus for autocalibration of a wearable electrode sensor system
US11868531B1 (en) 2021-04-08 2024-01-09 Meta Platforms Technologies, Llc Wearable device providing for thumb-to-finger-based input gestures detected based on neuromuscular signals, and systems and methods of use thereof
US11907423B2 (en) 2019-11-25 2024-02-20 Meta Platforms Technologies, Llc Systems and methods for contextualized interactions with an environment
US11921471B2 (en) 2013-08-16 2024-03-05 Meta Platforms Technologies, Llc Systems, articles, and methods for wearable devices having secondary power sources in links of a band for providing secondary power in addition to a primary power source
US11961494B1 (en) 2019-03-29 2024-04-16 Meta Platforms Technologies, Llc Electromagnetic interference reduction in extended reality environments

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4305401A (en) * 1979-05-16 1981-12-15 Hughes Aircraft Company Digital watch/infrared plethysmograph having a quick release remote pulse sensor having a finger cuff
US4409983A (en) * 1981-08-20 1983-10-18 Albert David E Pulse measuring device
US6491647B1 (en) * 1998-09-23 2002-12-10 Active Signal Technologies, Inc. Physiological sensing device
US20100217345A1 (en) * 2009-02-25 2010-08-26 Andrew Wolfe Microphone for remote health sensing

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4305401A (en) * 1979-05-16 1981-12-15 Hughes Aircraft Company Digital watch/infrared plethysmograph having a quick release remote pulse sensor having a finger cuff
US4409983A (en) * 1981-08-20 1983-10-18 Albert David E Pulse measuring device
US6491647B1 (en) * 1998-09-23 2002-12-10 Active Signal Technologies, Inc. Physiological sensing device
US20100217345A1 (en) * 2009-02-25 2010-08-26 Andrew Wolfe Microphone for remote health sensing

Cited By (43)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11921471B2 (en) 2013-08-16 2024-03-05 Meta Platforms Technologies, Llc Systems, articles, and methods for wearable devices having secondary power sources in links of a band for providing secondary power in addition to a primary power source
US11079846B2 (en) 2013-11-12 2021-08-03 Facebook Technologies, Llc Systems, articles, and methods for capacitive electromyography sensors
US11666264B1 (en) 2013-11-27 2023-06-06 Meta Platforms Technologies, Llc Systems, articles, and methods for electromyography sensors
CN103860170A (zh) * 2014-03-11 2014-06-18 天津师范大学 电导生物反馈训练仪
CN108882886B (zh) * 2016-03-29 2023-02-28 小利兰·斯坦福大学托管委员会 接近度传感器电路以及相关的感测方法
EP3435855A4 (fr) * 2016-03-29 2019-11-20 The Board of Trustees of the Leland Stanford Junior University Circuits de capteur de proximité et procédés de détection associés
JP2019515722A (ja) * 2016-03-29 2019-06-13 ザ ボード オブ トラスティーズ オブ ザ レランド スタンフォード ジュニア ユニバーシティー 近接センサ回路及びその関連感知方法
JP7251763B2 (ja) 2016-03-29 2023-04-04 ザ ボード オブ トラスティーズ オブ ザ レランド スタンフォード ジュニア ユニバーシティー ウェアラブル装置、ウェアラブル機器の一部に用いる装置及び血流力学的モニタリング方法
CN108882886A (zh) * 2016-03-29 2018-11-23 小利兰·斯坦福大学托管委员会 接近度传感器电路以及相关的感测方法
US11185289B2 (en) 2016-04-11 2021-11-30 Hill-Rom Services, Inc. Capacitive sensor for respiratory monitoring
EP3231356A1 (fr) 2016-04-11 2017-10-18 Hill-Rom Industries SA Capteur capacitif destiné à la surveillance respiratoire
US10656711B2 (en) 2016-07-25 2020-05-19 Facebook Technologies, Llc Methods and apparatus for inferring user intent based on neuromuscular signals
US11337652B2 (en) 2016-07-25 2022-05-24 Facebook Technologies, Llc System and method for measuring the movements of articulated rigid bodies
US10990174B2 (en) 2016-07-25 2021-04-27 Facebook Technologies, Llc Methods and apparatus for predicting musculo-skeletal position information using wearable autonomous sensors
US11635736B2 (en) 2017-10-19 2023-04-25 Meta Platforms Technologies, Llc Systems and methods for identifying biological structures associated with neuromuscular source signals
US11069148B2 (en) 2018-01-25 2021-07-20 Facebook Technologies, Llc Visualization of reconstructed handstate information
US11036302B1 (en) 2018-05-08 2021-06-15 Facebook Technologies, Llc Wearable devices and methods for improved speech recognition
US10937414B2 (en) 2018-05-08 2021-03-02 Facebook Technologies, Llc Systems and methods for text input using neuromuscular information
US11216069B2 (en) 2018-05-08 2022-01-04 Facebook Technologies, Llc Systems and methods for improved speech recognition using neuromuscular information
CN109662702A (zh) * 2018-05-23 2019-04-23 李芝宏 电容式脉搏检测系统及方法
US10687759B2 (en) 2018-05-29 2020-06-23 Facebook Technologies, Llc Shielding techniques for noise reduction in surface electromyography signal measurement and related systems and methods
US11129569B1 (en) 2018-05-29 2021-09-28 Facebook Technologies, Llc Shielding techniques for noise reduction in surface electromyography signal measurement and related systems and methods
US10970374B2 (en) 2018-06-14 2021-04-06 Facebook Technologies, Llc User identification and authentication with neuromuscular signatures
US11045137B2 (en) 2018-07-19 2021-06-29 Facebook Technologies, Llc Methods and apparatus for improved signal robustness for a wearable neuromuscular recording device
WO2020018892A1 (fr) * 2018-07-19 2020-01-23 Ctrl-Labs Corporation Procédés et appareil pour une robustesse de signal améliorée pour un dispositif d'enregistrement neuromusculaire portable
US11179066B2 (en) 2018-08-13 2021-11-23 Facebook Technologies, Llc Real-time spike detection and identification
US10842407B2 (en) 2018-08-31 2020-11-24 Facebook Technologies, Llc Camera-guided interpretation of neuromuscular signals
US10905350B2 (en) 2018-08-31 2021-02-02 Facebook Technologies, Llc Camera-guided interpretation of neuromuscular signals
US11567573B2 (en) 2018-09-20 2023-01-31 Meta Platforms Technologies, Llc Neuromuscular text entry, writing and drawing in augmented reality systems
US10921764B2 (en) 2018-09-26 2021-02-16 Facebook Technologies, Llc Neuromuscular control of physical objects in an environment
US10970936B2 (en) 2018-10-05 2021-04-06 Facebook Technologies, Llc Use of neuromuscular signals to provide enhanced interactions with physical objects in an augmented reality environment
US11941176B1 (en) 2018-11-27 2024-03-26 Meta Platforms Technologies, Llc Methods and apparatus for autocalibration of a wearable electrode sensor system
US11797087B2 (en) 2018-11-27 2023-10-24 Meta Platforms Technologies, Llc Methods and apparatus for autocalibration of a wearable electrode sensor system
US10905383B2 (en) 2019-02-28 2021-02-02 Facebook Technologies, Llc Methods and apparatus for unsupervised one-shot machine learning for classification of human gestures and estimation of applied forces
US11481030B2 (en) 2019-03-29 2022-10-25 Meta Platforms Technologies, Llc Methods and apparatus for gesture detection and classification
US11961494B1 (en) 2019-03-29 2024-04-16 Meta Platforms Technologies, Llc Electromagnetic interference reduction in extended reality environments
US11481031B1 (en) 2019-04-30 2022-10-25 Meta Platforms Technologies, Llc Devices, systems, and methods for controlling computing devices via neuromuscular signals of users
US11493993B2 (en) 2019-09-04 2022-11-08 Meta Platforms Technologies, Llc Systems, methods, and interfaces for performing inputs based on neuromuscular control
US11907423B2 (en) 2019-11-25 2024-02-20 Meta Platforms Technologies, Llc Systems and methods for contextualized interactions with an environment
CN112099669B (zh) * 2020-09-11 2023-02-10 合肥工业大学 用于腕背部手势识别的驻极体电容式压力传感器单元阵列
CN112099669A (zh) * 2020-09-11 2020-12-18 合肥工业大学 用于腕背部手势识别的驻极体电容式压力传感器单元阵列
US11868531B1 (en) 2021-04-08 2024-01-09 Meta Platforms Technologies, Llc Wearable device providing for thumb-to-finger-based input gestures detected based on neuromuscular signals, and systems and methods of use thereof
CN114571505A (zh) * 2022-02-28 2022-06-03 深圳市越疆科技有限公司 基于自电容检测的电子皮肤模块、机械臂和设备

Similar Documents

Publication Publication Date Title
WO2012155157A1 (fr) Capteur capacitif de support multiple
US8079247B2 (en) Impact detection system
US5099702A (en) Perimeter mounted polymeric piezoelectric transducer pad
US8677802B2 (en) Sensing modules and methods of using
US10136543B1 (en) Inductance-based user interface elements
KR20190104374A (ko) 힘 저항 센서 어레이를 사용한 혈압 측정 시스템
US11395600B2 (en) Vibration waveform sensor and pulse wave detection device
EP2734809A1 (fr) Procédé permettant d'améliorer la capacité de détection d'un changement de hauteur par un capteur de pression d'air, et unité de détection servant à déterminer un changement de hauteur
KR20030004387A (ko) 신체 동작 검출 장치
TW201325552A (zh) 肌能參數感測器
EP1519165A2 (fr) Capteur de vibrations piézoélectrique
TW201701825A (zh) 將壓力轉換到非侵入式脈搏感測器
CN210513399U (zh) 一种振动感测装置
CN107396275B (zh) 一种振幅检测装置、方法及移动终端
JP5476153B2 (ja) 携帯情報端末
EP3809956B1 (fr) Timbre jetable de surveillance de la santé et des signes vitaux
EP1571990B1 (fr) Controle d'activite
CN208464097U (zh) 一种运动监控系统
JP2009226025A (ja) 生体情報測定装置
CN2910111Y (zh) 一种高灵敏度触觉传感器
WO2022077242A1 (fr) Dispositif à porter sur soi pour détecter des signaux physiologiques et système et procédé pour l'utiliser
CN210019300U (zh) 一种无线无源脉搏测试装置及其应用的手机壳和穿戴装置
US20200085328A1 (en) Device for Monitoring of Patient's Vital Signs
Huang et al. A wireless flexible pressure sensor for human motion detection
CN112511933A (zh) 一种麦克风

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12731888

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12731888

Country of ref document: EP

Kind code of ref document: A1