WO2018206122A1

WO2018206122A1 - Devices and methods for detecting viral particles

Info

Publication number: WO2018206122A1
Application number: PCT/EP2017/061496
Authority: WO
Inventors: VAN Bart Robert Nicolaas GRINSVEN; Thomas Jan CLEIJ
Original assignee: Universiteit Maastricht; Academisch Ziekenhuis Maastricht
Priority date: 2017-05-12
Filing date: 2017-05-12
Publication date: 2018-11-15

Abstract

A device (100) for detecting viral particles (132) includes a polymer material (112) over a substrate (110); a heat transfer element (114) thermally coupled to the substrate; a temperature modification device (118) thermally coupled to the heat transfer element; a controller (121) to produce a thermal (202) wave emanating from the heat transfer element; a flow cell (122) located and configured to pass a liquid (124) over the polymer material; a temperature sensor (134) to detect a temperature (T2) of the liquid passing over the polymer material; and a processor (123) to calculate a concentration of viral particles (132) in the liquid based at least in part on a phase shift between the thermal wave at the heat transfer element and an attenuated thermal wave (204) in the liquid. Related methods of forming such a device and detecting viral particles using said device and Thermal Wave Transport Anaysis (TWTA) are also disclosed.

Description

DEVICES AND METHODS FOR DETECTING VIRAL PARTICLES

TECHNICAL FIELD

Embodiments of the present disclosure relate generally to devices and methods of detecting viral particles using polymer materials, such as over a heat sink configured to produce a thermal wave.

BACKGROUND

The detection of viral particles or viruses in a fast, selective and sensitive manner is vital in diverse fields ranging from the diagnosis, prevention and control of infectious diseases to application in plant biology or agriculture. Current gold standard virus detection kits are commonly based on polymerase chain reaction (PCR), enzyme-linked immunosorbent assays or microbiological analysis of infected cell cultures. Although these methods are very sensitive, there are many drawbacks associated with their use including long processing times (typically 24 hours) and the need for expensive laboratory equipment and trained personnel.

Therefore, a lot of research effort focused on the development of low-cost biosensor platforms for viral detection over the past few decades. These biosensor tools are able to selectively bind their target and allow for fast and label-free detection of viruses up to the single virus particle level. Despite these successes, the translation into commercial diagnostic applications is often troublesome as the chemical, thermal and physical stability of biological recognition elements is rather poor. In addition, their synthesis is labor-intensive and expensive and their coupling to transducers is often troublesome, creating a need for carefully optimized linker molecules.

Synthetic receptors overcome many of the drawbacks associated with classical biological recognition elements.

Molecularly imprinted polymers (MIPs) have been described for detecting chemical substances in complex mixtures. In modern research, these polymers are of increasing interest for bioanalytical applications. Advantages of using these MIPs include easy and cheap production; mechanical, chemical, and thermal stability; reusability; and long shelf life. In recent years, the concept of molecular imprinting has been extended to surface imprinting of thin polymer films with micrometer-sized cells to create so-called "surface imprinted polymers" (SIPs) for the detection of proteins, glycoproteins, plant viruses, human viruses, bacteria, pollen, yeast cells, and even mammalian red blood cells. SIPs are polymeric materials with indentations at the surface, with a form and function matching part of a desired target. SIPs are suitable for bonding with larger objects (e.g., cells, bacteria, eic), which do not diffuse quickly through pores of an MIP. Imprinting may occur after polymerization by softening the polymer. The detection of cells using biosensors described in literature is conventionally done by gravimetric detection, electronic read-out platforms or micro-fluidic techniques. However, these techniques are often time- consuming, provide difficulties for analysis, or require expensive equipment.

For example, temperature resistance of substrates having MIPs attached thereto based on the concentration of analytes is described in U.S. Patent Application Publication 2014/001 1 198 A1 , "Heat-Transfer Resistance Based Analysis Bioparticles," published January 9, 2014, the entire disclosure of which is hereby incorporated herein by reference.

A low-cost sensor platform providing the capability to differentiate between cells with slight differences in shape, size, and functionalities in functional groups on their surface would be a valuable tool for modern research and industry.

DISCLOSURE

In some embodiments, a device for detecting viral particles includes a substrate having a polymer material formed on a surface thereof; a heat sink thermally coupled to a surface of the substrate opposite the polymer material; a temperature modification device thermally coupled to the heat sink; a controller configured to cause the temperature modification device to produce a thermal wave emanating from the heat sink; and a flow cell located and configured to pass a liquid over the polymer material of the substrate. The device may further include a temperature sensor located and configured to detect a temperature of the liquid passing over the polymer material and a processor configured to calculate a concentration of viral particles in the liquid based at least in part on a phase shift between the thermal wave at the heat sink and an attenuated thermal wave in the liquid.

A method for detecting viral particles includes passing a liquid containing a virus over a polymer material on a substrate; binding the viral particles to the polymer material; providing a thermal wave from a heat sink to the polymer material through the substrate; detecting a temperature of the liquid; and calculating a concentration of the viral particles in the liquid based at least in part on a phase shift between the thermal wave produced by the heat sink and an attenuated thermal wave in the liquid.

A method of forming a device for detecting viral particles includes forming a polymer material over a surface of a substrate; thermally coupling a heat sink to a surface of the substrate opposite the polymer material; thermally coupling a temperature modification device to the heat sink; configuring a controller to cause the temperature modification device to produce a thermal wave emanating from the heat sink; configuring a flow cell to pass a liquid over the polymer material of the substrate; configuring a temperature sensor to detect a temperature of the liquid passing over the polymer material; and configuring a processor to calculate a concentration of viral particles in the liquid based at least in part on a phase shift between the thermal wave at the heat sink and an attenuated thermal wave in the liquid.

In some embodiments, a method for characterizing viral particles includes passing a liquid comprising viral particles of a first species and viral particles of a second species over and in contact with a polymer material on a substrate. The polymer material is formulated to bind to the viral particles of first virus species, and the viral particles of the first virus species binds to the polymer material with a higher affinity than the viral particles of the second virus species. A heat transfer property of the polymer material varies based on an amount of the viral particles bound thereto. The method further includes binding a portion of the viral particles of the first virus species and the viral particles of the second virus species to the polymer material, removing at least a portion of the viral particles of the second virus species from the polymer material, detecting a temperature of the substrate, and calculating a concentration of the viral particles of the first virus species in the liquid based at least in part on the temperature of the substrate.

In other embodiments, a method for characterizing a liquid comprising viral particles includes passing a liquid containing viral particles of a first virus species and at least viral particles of a second virus species over and in contact with a polymer material on a substrate. The polymer material is formulated to bind to viral particles of the first virus species, and viral particles of the first virus species binds to the polymer material with a higher affinity than viral particles of the at least a second virus species. A heat transfer property of the polymer material varies based on an amount of material bound thereto. The method further includes binding a portion of viral particles of the first virus species and a portion of viral particles of the at least a second virus species to the polymer material, washing the polymer material to remove viral particles of the at least a second virus species therefrom, passing the liquid over the polymer material after washing the polymer material, washing the polymer material at least a second time to remove viral particles of the at least a second virus species therefrom, detecting a temperature of the substrate, and calculating a concentration of viral particles of the first virus species in the liquid based at least in part on the temperature of the polymer material.

In yet another example, the method for characterizing viral particles comprises the steps of providing heat from a heat transfer element through the substrate; detecting a first temperature at the side of substrate opposite to the side where the polymer is provided detecting a second temperature at the side of substrate where the polymer is provided, and wherein the step of calculating the concentration of the first virus species in the liquid comprises the step of calculating the heat transfer property of the polymer material based on the first and second temperature and the amount of heat being provided by the heat transfer element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic diagram showing a device for detecting a virus;

FIG. 2 is a simplified schematic representation showing how a thermal wave may travel in the device of FIG. 1 ;

FIG. 3 is a simplified schematic diagram showing another device for detecting a virus;

FIG. 4 is a graph showing changes in temperature as measured according to an embodiment of the disclosure;

FIG. 5 is a graph showing time-dependent values of thermal resistance as measured according to an embodiment of the disclosure;

FIG. 6 is a graph showing thermal waves measured after passing through a substrate according to an embodiment of the disclosure;

FIG. 7 is a graph showing the phase shift of the thermal waves shown in FIG. 6 as measured according to an embodiment of the disclosure;

FIG. 8 is a graph showing changes in temperature as measured according to an embodiment of the disclosure;

FIG. 9 is a graph showing time-dependent values of thermal resistance as measured according to an embodiment of the disclosure; FIG. 10 is a graph showing thermal waves measured after passing through a substrate according to an embodiment of the disclosure;

FIG. 1 1 is a graph showing the phase shift of the thermal waves shown in FIG. 10 as measured according to an embodiment of the disclosure.

MODE(S) FOR CARRYING OUT THE INVENTION

The illustrations presented herein are not actual views of any particular device or method, but are merely idealized representations employed to describe example embodiments of the present disclosure. Elements common between figures may retain the same numerical designation.

As used herein, the term "may" encompasses the word "can," and the term "may be" encompasses the words "is" or "are," depending on context. Furthermore, presence of the word "may" is intended to indicate options for practicing or implementing

embodiments of the disclosure, without limitation.

FIG. 1 is a simplified schematic diagram showing a device 100 for detecting a virus. In an example, the device 100 is configured to detect a target analyte, here viral particles species.

The device 100 may include a substrate 1 10 having a polymer material 1 12 located over a surface thereof. For example, the polymer material 1 12 may be formed or disposed over a generally planar surface of the substrate 1 10, and another, opposite generally planar surface of the substrate 1 10 may be free of the polymer material 1 12. In some embodiments, the substrate 1 10 may include a metal (e.g., aluminum), an alloy, a semiconductor (e.g., silicon, doped diamond, eic), an electrically insulating material (e.g., undoped diamond). The polymer material 1 12 may include any material for which a heat transfer property varies based on an amount of the viral particles bound thereto. For example, the thermal conductivity, thermal diffusivity, heat capacity, or another property of the polymer material 1 12 may vary with concentration of the viral particles on the surface thereof.

In some embodiments, the polymer material 1 12 may include an imprinted polymer, such as a molecularly imprinted polymer (MIP) or a surface imprinted polymer (SIP). MIPs and SIPs may also be referred to in the art as "plastic" antibodies. MIPs typically possess a high affinity for a specific binding partner, so that when such binding partners are contacted with the MIP, the molecules bind with the MIP. MIPs are synthetic receptors that contain nanocavities with high affinity for their respective target analytes. Imprinting (i.e., formation of the nanocavities) is often part of the polymerization process. MIPs are able to specifically bind targets, including bacteria, varying from small ions to large cells in complex matrices. Binding of molecules to the MIP may alter some properties of the MIP, such as thermal properties, mechanical properties, electrical properties, etc. The altered property of an MIP may, therefore, be used to detect a presence of such molecules at relatively low concentrations. MIPs are described in, for example, U.S. Patent Application Publication 2009/0281272 A1 , "Monodisperse

Molecularly Imprinted Polymer Beads," published November 12, 2009, the entire disclosure of which is hereby incorporated herein by reference.

Similarly, SIPs typically possess a high affinity for a specific binding partner, but may typically bind to relatively larger objects (e.g., cells, bacteria, etc.) that do not diffuse quickly through pores of an MIP. SIPs may be polymer materials formed over a surface, then imprinted after polymerization by softening the polymer.

In certain embodiments, the polymer material 1 12 may include DNA, RNA, proteins, or portions or analogs thereof. For example, the device 100 may include a substrate 1 10 (e.g., a diamond surface) functionalized with a polymer material 1 12 such as DNA, RNA, a protein, a polypeptide, a nucleic acid polymer, a probe, or a portion or analog thereof (e.g., complementary DNA, antibodies, eic). The polymer material 1 12 may be formulated to possess a high affinity for a specific binding partner, so that when such binding partners are contacted with the surface of the substrate 1 10, the molecules bind with the polymer material 1 12. The polymer material 1 12 may also bind to analogues of the binding partner (e.g., a material having similar functionality as the binding partner), though not necessarily with the same affinity as binding with the binding partner itself. In some embodiments, the polymer material 1 12 may include at least about seven (7) repeating units, such as ten (10) repeating units or more.

In some embodiments, the polymer material 1 12 may include a material screen- printed onto the substrate 1 10. Screen-printed materials may be manufactured efficiently and in mass quantities, with relatively high uniformity in comparison with other materials.

The device 100 may further include a heat sink 1 14 thermally coupled to a surface of the substrate 1 10, such as a surface opposite the polymer material 1 12. Though referred to as a heat "sink" for the sake of simplicity, the heat sink 1 14 may be configured to provide heat to or remove heat from the substrate 1 10 and, so, may also be characterized as a heat transfer element 1 14. The heat sink or heat transfer element 1 14 may be a material having a high thermal conductivity, such as a transition metal (e.g., copper, silver, etc.) or an alloy or mixture thereof. In some embodiments, the polymer material 1 12 may be applied to the heat sink 1 14 itself. The heat sink 1 14 may be thermally coupled to a temperature sensor 1 16 (e.g., a thermocouple or another device) configured to detect a temperature of the heat sink 1 14, and to a temperature modification device 1 18 configured to maintain the temperature of the heat sink 1 14. The temperature modification device 1 18 may include, for example, a thermoelectric device, a heat exchanger, a fan, a resistance heater, etc. The temperature sensor 1 16 may be a resistor having a resistance that varies with temperature. If the properties of the heat sink 1 14 are known (e.g., if a relationship between a control signal to the modification device 1 18 and the temperature of the heat sink 1 14 is well characterized), the temperature sensor 1 16 may be omitted. In some embodiments, the temperature sensor 1 16 may be integral to the temperature modification device 1 18. For example, the internal resistance of the temperature modification device 1 18 itself may be measured to determine its temperature.

The temperature sensor 1 16 and the temperature modification device 1 18 may be connected to a controller 121 configured (i.e., programmed) to control the temperature modification device 1 18 to cause the heat sink 1 14 to produce a thermal wave emanating from the heat sink 1 14 and through the substrate 1 10 (including the polymer material 1 12 thereon). For example, the controller 121 and a processor 123 may be incorporated into a computer 120 (e.g., the controller 121 may be an input-output card configured to receive and provide electrical signals, and may be configured to receive signals from the processor 123). In some embodiments, the controller 121 may be a proportional-integral- derivative (PID) controller capable of changing the temperature of the heat sink 1 14 by a small amount on a relatively short time scale. For example, the controller 121 may change the temperature of the heat sink 1 14 by about 0.5°C or less, about 0.2°C or less, or even about 0.05°C or less. Thus, the thermal wave may have an amplitude of about 1 .0°C or less, about 0.4°C or less, or even about 0.10°C or less. The controller 121 may be capable of changing the temperature of the heat sink 1 14 via the temperature modification device 1 18 from one set point to another and back to form a thermal wave having a frequency from about 0.001 to about 0.5 Hz, such as from about 0.005 to about 0.1 Hz, or from about 0.01 to about 0.05 Hz. In some embodiments, the controller 121 , the temperature modification device 1 18, and the heat sink 1 14 may together produce a thermal wave having a variable frequency. Based on a measurement from the

temperature sensor 1 16 (if present), a known input to the temperature modification device 1 18, or other means, properties of the thermal wave may be known (e.g., a phase, amplitude, frequency at a specific time, rate of frequency change, eic).

In other embodiments, the controller 121 may be configured to maintain the heat sink 1 14 at a constant temperature. Detection of analytes using a heat sink at constant temperature is described in U.S. Patent Application Publication 2015/0219584 A1 , "Biosensor Using Impedimentric Real-Time Monitoring," published August 6, 2015, the entire disclosure of which is hereby incorporated herein by reference.

The device 100 may further include a flow cell 122 configured to pass a liquid 124 over the polymer material 1 12 of the substrate 1 10. The flow cell 122 may define a void 126 adjacent the polymer material 1 12 of the substrate 1 10, as well as an inlet 128 and an outlet 130 through which the liquid 124 may flow. An O-ring 131 or another appropriate sealing mechanism may retain the liquid 124 within the flow cell 122 adjacent the polymer material 1 12 over the substrate 1 10.

The liquid 124 may include a viral particles species 132 that specifically binds to the polymer material 1 12 and change thermal properties thereof, as described above. The viral particles 132 (which may include viral particles of multiple virus species 132a and 132b) may specifically bind to the polymer material 1 12 and changes thermal properties thereof, as described above. If viral particles of multiple virus species 132a and 132b are present in the liquid 124, the viral particles 132a, 132b may have similar functionalities, such that each of the viral particles 132a, 132b bind to the polymer material 1 12. The viral particles 132a, 132b may bind to the polymer material 1 12 with different affinities. In some embodiments, viral particles of the first virus species 132a may include viral particles of a first type, and the second virus species 132b may include an analogue virus or viral particles of a different, second type.

A temperature sensor 134 (e.g., a thermocouple or another device) may be configured to detect a temperature of the liquid 124 in (e.g., flowing through) the flow cell 122. The computer 120 may record the temperature of the liquid 124 by, for example, measuring a resistance of the temperature sensor 134 via the controller 121 and/or the processor 123, and correlating that resistance to a temperature. The temperature of the liquid 124 may be different from the temperature of the heat sink 1 14, and may vary based at least in part on the presence or absence of the viral particles 132 and its concentration in the liquid 124. For example, temperature resistance of substrates based on the concentration of analytes is described in U.S. Patent Application Publication

2014/001 1 198 A1 , "Heat-Transfer Resistance Based Analysis Bioparticles," published January 9, 2014, the entire disclosure of which is hereby incorporated herein by reference.

In some embodiments, the processor 123 may be configured to calculate a concentration of the viral particles 132 in the liquid 124 based at least in part on a phase shift between the thermal wave produced by the heat sink 1 14 and an attenuated thermal wave in the liquid 124 after the thermal wave passes through the substrate 1 10 and the polymer material 1 12.

FIG. 2 is a simplified schematic representation showing how the thermal wave may travel in the device 100 of FIG. 1. FIG. 2 includes some of the components shown in FIG. 1 , but shows them separated to allow representation of thermal waves traveling through and between the components. In particular, FIG. 2 shows the heat sink 1 14 thermally coupled to the temperature modification device 1 18 and the temperature sensor 1 16, which are connected to the computer 120. The concentration of the viral particles 132 may be measured based on the differences between the thermal wave at the heat sink 1 14 and the thermal wave in the liquid 124, without a separate calibration step.

The heat sink 1 14 may produce a thermal wave 202 and transfer the thermal wave 202 to the substrate 1 10 and the polymer material 1 12 thereon. For example, if the heat sink 1 14 is initially maintained at a constant temperature of 37°C, the thermal wave 202 may be produced by heating the heat sink 1 14 to a temperature of 37.1 °C and then cooling the heat sink 1 14 to a temperature of 36.9°C. The heating and cooling of the heat sink 1 14, driven by the temperature modification device 1 18, may cause the substrate 1 10 and the polymer material 1 12 to heat and cool in a corresponding manner. The thermal wave 202 may have an amplitude αι and a frequency φ-ι . The amplitude αι and/or the frequency ψι may vary with time. For example, the thermal wave 202 may have a continuously varying frequency φ-ι .

As discussed above, the presence or absence of the viral particles 132 on the substrate 1 10 may change the thermal conductivity, thermal diffusivity, heat capacity, or another property of the polymer material 1 12. FIG. 2 illustrates conceptually that the polymer material 1 12 may define cavities 136 therein adapted to interact with at least a portion of the virus 132. Without being bound to any particular theory, the cavities 136 may be configured to act to specifically bind the viral particles 132. Thus, the polymer material 1 12 may receive particles or molecules of the viral particles 132 from the liquid 124 in some of the cavities 136, based on the concentration of the viral particles 132 in the liquid 124. The liquid 124 and the polymer material 1 12 may reach equilibrium at a given temperature, such that the viral particles 132 binds to and separates from the polymer material 1 12 at equal rates. The thermal properties of the polymer material 1 12 may depend in part on the fraction of the cavities 136 bound to particles or molecules of the viral particles 132.

The substrate 1 10 and/or the polymer material 1 12 thereon may alter the thermal wave 202 passing therethrough to form an attenuated thermal wave 204. The attenuated thermal wave 204 may be detected by the temperature sensor 134, and recorded by the computer 120. The attenuated thermal wave 204 may have an amplitude a₂ and a frequency φ₂, which may be different from the amplitude αι and a frequency ψι of the thermal wave 202. The differences in the amplitudes α-ι, a₂ and/or the frequencies φ-ι, φ₂ may be correlated to the amount of the viral particles 132 bound to the polymer material 1 12, and thus, to the concentration of the viral particles 132 in the liquid 124.

Measurement of the differences in the amplitudes α-ι, a₂ and/or the frequencies φ-ι, φ₂ may allow the device 100 to detect relatively lower amounts of the viral particles 132 bound to the polymer material 1 12 (corresponding to lower concentrations of the viral particles 132 in the liquid 124) as compared with conventional methods of measuring the temperature of the liquid 124 at steady state.

In other embodiments, the processor 123 may be configured to calculate a concentration of the viral particles 132 based on a steady-state temperature difference between the heat sink 1 14 and the liquid 124.

In certain embodiments, the viral particles 132 may bind to a non-planar surface.

For example, FIG. 3 is a simplified schematic diagram showing another device 200 for detecting the viral particles 132. The device 200 may include a thermocouple 210 having a base material 212 formed over a surface thereof. For example, the base material 212 may be formed over a generally cylindrical surface of the thermocouple 210, such that an entire end of the thermocouple 210 is enclosed. The thermocouple 210 may include a junction between two materials formulated to provide a temperature-dependent voltage between electrical contacts 216, 218. In some embodiments, the thermocouple 210 may include one or more of a metal (e.g., platinum, gold, iridium, palladium, etc.) or an alloy (e.g., a nickel alloy, a copper alloy, a rhodium alloy, a rhenium alloy, an iron alloy, a molybdenum alloy, eic).

The base material 212 may be a polymer material such as polylactic-(L)-acid, which may be referred to in the art as PLLA. PLLA is transparent, inexpensive to produce from environmentally renewable sources (e.g., starch or sugar-containing agricultural products), biodegradable, and biocompatible. Furthermore, PLLA can be solubilized in chloroform to enable application to the thermocouple 210. Another material, rather than PLLA, may be selected to be the base material 212, based on desired properties. In some embodiments, the base material 212 may include polyurethane, polylactic acid, polycaprolactone, poly(lactic-co-glycolic acid), poly(D,L-lactide-co-glycolide), or another selected polymer. The base material 212 may be in the form of a thin, smooth, and homogeneous coating over the exterior of the thermocouple 210. Uniformity of the coating by base material 212 may enable to the device 200 to yield reproducible results. The thickness of the base material 212 may be selected in view of the thermal resistance of the base material 212 to affect the rate at which heat may flow toward or away from the thermocouple 210. Thus, a thinner base material 212 may be beneficial for applications in which a fast response is desired or temperature differentials are small.

The base material 212 may be selected to exhibit at least some elasticity, such that the device 200 may be flexible to allow bending of the thermocouple 210 without breaking the base material 212. This may enable the device 200 to be used for applications requiring tight clearance or bends (e.g., in vivo use in catheters).

An assay polymer 214 may be on a surface of the base material 212. In some embodiments, the assay polymer 214 may be directly bonded to the surface of the thermocouple 210, and the base material 212 may be omitted. The assay polymer 214 may include a material for which a heat transfer property varies responsive to an amount of the viral particles bound thereto. For example, the thermal conductivity, thermal diffusivity, heat capacity, or another property of the assay polymer 214 may vary with concentration of the viral particles on the surface thereof.

In some embodiments, the assay polymer 214 may include an imprinted polymer (an MIP or SIP), DNA, RNA, proteins, or portions or analogs thereof (e.g., antibodies). The assay polymer 214 may be configured to possess a high affinity for a specific binding partner, so that when such binding partners are contacted with the surface of the thermocouple 210, the molecules bind with the assay polymer 214. In some embodiments, the assay polymer 214 may include at least about seven (7) repeating units, such as ten (10) repeating units or more.

In some embodiments, the device 200 may include a processor 223 programmed to calculate an amount of the viral particles bound to the assay polymer 214. The processor 223 may calculate a concentration of the viral particles in a liquid in contact with the device 200 based at least in part on the amount of the viral particles bound to the assay polymer 214. For example, the processor 223 may calculate the amount of the viral particles by a method as disclosed in U.S. Patent Application Publication 2014/001 1 198 A1 , "Heat-Transfer Resistance Based Analysis Bioparticles," published January 9, 2014; or U.S. Patent Application Publication 2014/0242605 A1 , "Heat-Transfer Resistance

Based Analysis of Bioparticles," published August 28, 2014, the entire disclosures of each of which are hereby incorporated herein by reference. In certain embodiments, the processor 223 may be used to detect a phase shift between a thermal wave at or emanating from a heat sink and an attenuated thermal wave at the thermocouple 210. The processor 223 may then calculate the concentration of the viral particles in the liquid based at least in part on a difference in amplitude between the thermal wave at the heat sink and the attenuated thermal wave at the thermocouple 210.

Returning again to FIG. 1 , the polymer material 1 12 may be formed or otherwise provided over the substrate 1 10. For example, the polymer material 1 12 may be screen- printed onto a metal substrate 1 10. Screen-printing may be performed efficiently and scaled to produce mass quantities, with relatively high uniformity in comparison with other methods. Screen-printing of substrates is described in, for example, U.S. Patent

Application Publication 2012/0186999 A1 , "Electrochemical Sensor," published July 26, 2012, the entire disclosure of which is hereby incorporated herein by reference.

The heat sink 1 14 may be thermally coupled to the substrate 1 10 at a surface opposite the polymer material 1 12. For example, the heat sink 1 14 may be placed in direct physical contact with the substrate 1 10 such that heat can flow from the heat sink 1 14 to the substrate 1 10 by conduction. In some embodiments, a thermally conductive material (e.g., a polymerizable liquid matrix having a thermally conductive filler) may be placed in physical contact with the heat sink 1 14 and the substrate 1 10 to eliminate air gaps between the heat sink 1 14 and the substrate 1 10. Similarly, the temperature modification device 1 18 may be thermally coupled to the heat sink 1 14 by direct physical contact, through a thermally conductive material, or by other appropriate means. The controller 121 (e.g., a PID controller) may be electrically connected to the temperature modification device 1 18 to provide power sufficient to drive the temperature of the heat sink 1 14, and to cause the temperature modification device 1 18 to change the temperature of the heat sink 1 14 to produce the thermal wave 202 (FIG. 2).

The flow cell 122 may be secured adjacent the substrate 1 10 such that the liquid

124 enters the flow cell 122 through the inlet 128, contacts the polymer material 1 12, and then leaves the flow cell 122 through the outlet 130. In some embodiments, the flow cell 122 may be connected to the heat sink 1 14 by one or more fasteners 138 (e.g., screws). In other embodiments, the flow cell 122 may be connected to the heat sink 1 14 by integral threads or by a slip-fit joint. The O-ring 131 or other seal may be configured to keep the liquid 124 from contacting the heat sink 1 14, the temperature modification device 1 18, or the back side of the substrate 1 10 directly.

The temperature sensor 134 may be disposed within the void 126 of the flow cell 122 to measure the temperature of the liquid 124 flowing through the flow cell 122. The temperature sensor 134 may be secured to the flow cell 122 by an adhesive or other appropriate means. The temperature sensor 134 may be electrically connected to the processor 123, which may include an ohmmeter. The processor 123 may be configured to continuously detect the temperature at the temperature sensor 134, and to calculate the concentration of the viral particles 132 in the liquid 124 based at least in part on a phase shift between the thermal wave 202 (FIG. 2) produced by the heat sink 1 14 and the attenuated thermal wave 204 (FIG. 2) in the liquid 124.

Surprisingly, the device 100 shown in FIG. 1 and described above is also capable to detect any selected viral particles 132. During testing it has been found, for example, that the device 100 as described herein can be used for detecting, sensing, and quantifying viral particles (virions) in the liquid 124. The device 100 may be used for detecting, sensing, and quantifying particular viral particles, or discriminating types of viral particles in a complex mixture.

One of the many attractive features of molecular imprinting methods as disclosed herein is that it has been discovered that such molecular imprinting methods also can be applied to a diverse range of viral particles of different virus species. The imprinting of small, organic molecules (e.g., pharmaceuticals, pesticides, amino acids and peptides, nucleotide bases, steroids, sugars, etc.) is described in, for example, K. Haupt and K. Mosbach, "Molecularly Imprinted Polymers and Their Use in Biomimetic Sensors," Chem. Rev. 100, 2495-2504 (2000); and G. Mustafa and P. Lieberzeit, "MIP Sensors on the Way to Real-World Applications," in Springer Series on Chemical Sensors and Biosensors, vol. 12, pp. 167-187 (Springer, 2012). Somewhat larger organic compounds (e.g., peptides) can also be imprinted via similar approaches. Protocols for imprinting larger structures, such as proteins, cells, and mineral crystals have been proposed in, for example, M. Kempe, M. Glad, and K. Mosbach, "An Approach Towards Surface Imprinting Using the Enzyme Ribonuclease A," J. Molecular Recognition, 8, 35-39 (1995); S. Hjerten et al., "Gels Mimicking Antibodies in Their Selective Recognition of Proteins," Chromatographia 44, 227-234 (1997); H. Shi et al., "Template-Imprinted Nanostructured Surfaces for Protein Recognition," Nature 398, 593-597 (1999); A. Aherne et al. "Bacteria-Mediated Lithography of Polymer Surfaces," J. Am. Chem. Soc. 1 18, 8771 -8772 (1996); and S. M. D'Souza, et al., "Directed Nucleation of Calcite at a Crystal-Imprinted Polymer Surface," Nature 398, 312-316 (1999). Molecular imprinting as a bridge to drug advanced drug delivery is described in B. Sellergren and C. Allender, "Molecularly Imprinted Polymers: A Bridge to Advanced Drug Delivery," Advanced Drug Delivery Reviews 57, 1733-1741 (2005). The entire disclosures of each of the documents cited in this paragraph are hereby incorporated herein by reference.

Applying molecular imprinting methods as described in this patent application has led to the development of surface imprinting polymers (SIPs) which can be used in detecting viral particles.

To detect the viral particles 132, the liquid 124 containing the viral particles 132 may be passed through the flow cell 122, adjacent and in contact with the polymer material 1 12 over the substrate 1 10. The viral particles 132 (e.g., particles, molecules, or bacteria) binds to the polymer material 1 12, changing one or more thermal properties of the polymer material 1 12. The liquid 124 may flow continuously through the flow cell 122 during detection, or the flow may terminate before detection begins. The thermal wave 202 (FIG. 2) and the attenuated thermal wave 204 may travel through the liquid 124 whether the liquid 124 is flowing or stagnant. The thermal properties of liquid 124 may differ for flowing and stagnant liquids 124, but can be determined based on flow properties. In some embodiments, the flow cell 122 and the liquid 124 therein may be brought to a test temperature before detection of the viral particles 132. As discussed above, the polymer material 1 12 may be a molecularly imprinted polymer formulated to bind a particular viral particles 132 of interest. The thermal wave 202 (FIG. 2) is provided from the heat sink 1 14 to the polymer material 1 12 through the substrate 1 10. The controller 121 (e.g., a PID controller) may change the temperature of the heat sink 1 14 via the temperature modification device 1 18, such as by raising the temperature and lowering the temperature of the heat sink 1 14 by a preselected amount and at a preselected frequency. The change in the temperature of the heat sink 1 14 may be small enough that the change does not interfere significantly with other measurements that may occur simultaneously. For example, the average temperature of the liquid 124 in the flow cell 122 may be measured even though the temperature of the heat sink 1 14 is varying, so long as the time scale of the average temperature measurement is longer than the frequency of the variation and/or the amount of the temperature variation is small in comparison with the temperature change induced by the interaction of the viral particles 132 with the polymer material 1 12. In some embodiments, the heat sink 1 14 may provide a thermal wave 202 having a frequency from about 0.001 to about 0.5 Hz, such as from about 0.005 to about 0.1 Hz, or from about 0.01 to about 0.05 Hz. Furthermore, the frequency of the thermal wave 202 may vary during testing (e.g., the frequency may be continuously varied from a low frequency to a high frequency or vice versa). The thermal wave 202 may have an amplitude of about 1 .0°C or less, about 0.4°C or less, or even about 0.10°C or less.

The temperature of the liquid 124 in the flow cell 122 may be tested, and the result may be compared with the temperature of the heat sink 1 14.

The concentration of the viral particles 132 in the liquid 124 may be calculated at least in part on a phase shift between the thermal wave 202 produced by the heat sink 1 14 and the attenuated thermal wave 204 wave in the liquid 124. A comparison of the thermal wave 202 and the attenuated thermal wave 204 may be performed by the processor 123 based on responses of liquids of known concentration. In some embodiments, the comparison of the thermal wave 202 with the attenuated thermal wave 204 may be based at least in part on the amplitudes the phase shift, or another property.

Measurement of the thermal wave enables measurement of thermal resistance without significantly changing the overall temperature of the polymer material 1 12.

Without being bound to any particular theory, such a measurement appears to be a thermal analog to the measurement of capacitance or inductance in the field of electronics. For example, measuring resistance reveals some information about an electronic device or material, but measuring capacitance or impedance reveals additional information, such as how the device or material responds to a load. Similarly, measuring thermal resistance by the methods disclosed herein can reveal additional information that measuring a steady-state temperature difference cannot.

For example, when applying a thermal wave in a first example of the method according to the invention, different types of information are available in the form of a change in amplitude, frequency and/or phase of the attenuated thermal wave in the liquid upon binding of a target to the receptor. The phase shift may vary based on the frequency of the input. The amount of information provided by a thermal wave is much greater than steady-state analysis, and the information may enable detection or differentiation of a wider variety of materials.

Furthermore, and again without being bound to any particular theory, an increase in thermal mass of the polymer material 1 12 may occur upon binding of the viral particles 132 onto its receptor (i.e., the cavities 136). Before binding of the viral particles 132, the cavities 136 may be filled with liquid. Upon binding of the viral particles 132 into its receptor, the liquid may be replaced by the viral particles 132, thus increasing the thermal mass of the entire transducer system.

In some embodiments, the viral particles of the first virus species 132a may be distinguished from the viral particles of the second virus species 132b by removing the viral particles of the second virus species 132b from the polymer material 1 12.

Differences in affinity between the viral particles of the first virus species 132a and the viral particles of the second virus species 132b may facilitate such discrimination. In some embodiments, the viral particles of the first virus species 132a may be the template molecule used to form the polymer material 1 12, and the viral particles of the second virus species 132b may have some similar functionality. Therefore the viral particles of the second virus species 132b may bind, at least weakly, to the polymer material 1 12.

EXAMPLES

Example 1 : Preparation of viral particles-imprinted polyurethane layers

A spin-coating solution was prepared by dissolving 122 mg of

4,4'-diisocyanatodiphenylmethane, 222 mg of bisphenol A, and 25 mg of phloroglucinol in 500 μΙ_ of anhydrous tetrahydrofuran (THF). All reagents had a purity of at least 99.9% and were used as received from Sigma-Aldrich N.V., of Diegem, Belgium. The solution was polymerized up to its gel point at 65°C for 200 minutes. The solution was diluted in anhydrous THF in a 1 :5 ratio. Polyurethane layers with an average thickness of 1.2 ± 0.1 μηη, as measured with a profilometer (Dektak 3ST, Sloan Instruments Corporation, Santa Barbara, California, USA) were formed by spin-coating the solution for 60 s at 2000 rpm onto aluminum substrates each having a surface area of 1 cm².

Polydimethylsiloxane (PDMS) stamps were made using a Dow Corning

SYLGARD® 184 silicone elastomer kit purchased from Malvom N.V., of Schelle, Belgium. Viral particles-covered PDMS stamps were formed by applying 400 μΙ_ of a viral particles- suspension in PBS to each stamp. The viral particles were allowed to settle to the surface of the stamp for 60 s. The excess viral fluid was removed by spin-coating the stamps at 3000 rpm for 60 s to create a dense monolayer of viral particles on the stamp surface.

The viral particles-covered stamps were each pressed into the polyurethane layer on one of the aluminum substrates at a pressure of 70 Pa. The polyurethane was cured for 18 hours at 65°C in an inert atmosphere, after which the stamps were removed from the surfaces of the substrates. Template vial particles were washed off with ethanol and PBS, leaving behind selective binding cavities on the surfaces of the substrates. Thus, surface-imprinted polymers (SIPs) were prepared to be selective for each of Tobacco Mosaic Virus and Potato Virus X. Example 2: Heat-Transfer Method (HTM)

A flow cell having an inside diameter of 6 mm and a height of 4 mm, with a total interior volume of 1 10 μΙ, was made of acrylic (available under the trademark PERSPEX®, from Lucite International, of Lancashire, United Kingdom). The flow cell was coupled to a potentiostat, and was sealed with an O-ring. The contact area between the flow cell and the potentiostat system was 28 mm². The SIP-coated substrates (described in Example 1 ) were mounted horizontally and pressed mechanically onto a copper block, which served as a heat sink. The temperature T-i of the copper block was actively controlled by a proportional-integral-derivative (PID) controller with control parameters P = 10, I = 8, and D = 0, and measured by a thermocouple. The temperature T-i of the copper block was maintained at 37.00°C.

A second thermocouple was positioned above the surface of the SIP-coated substrates, which measured the temperature T₂ in the liquid. The thermal resistance, abbreviated as R_th (°C/W), was determined by dividing the temperature difference (T-i-T₂) by the input power P (in Watts) consumed while keeping the temperature constant at 37.00°C, as shown in Equation 1 :

Equation 1 : R_th = - ^T^.

The SI P-coated substrates were stabilized in PBS buffer (pH = 7.2) at the beginning of each experiment. A mixture of viral particles, containing Tobacco Mosaic Virus (TMV) and Potato Virus X (PVX) were introduced to the system by injecting a viral solution (PBS, 100 μg mL^"1) at a controlled flow rate of 2.5 mL/min. The SI P-coated substrates were stabilized, after which the SI P-coated substrates were flushed with PBS to remove any unbound bacteria from the SI P layer. After each injection, the signal is allowed to stabilize for half an hour. The thermal resistance can be monitored in time by dividing the difference between T-i and T₂ by the power over the power resistor. The HTM setup monitors the thermal resistance (R_th) at the solid-liquid interface at a rate of one measurement per second. The results of the HTM measurements are depicted in FIGU RES 4 and 5 as well as in FIGURES 8 and 9. Samples were imprinted with TMV and PVX particles as described in Example 1 . The results in Figures 4 and 5 illustrate the response of a TMV-imprinted SI P upon consecutive exposure to a solution containing PVX and TMV viral particles respectively. The HTM analysis (Figure 4 and 5) illustrates that both T₂ and R_th do not significantly change upon addition of a solution containing only PVX viral particles. However, the addition of a solution containing TMV viral particles results in a noticeable decrease in T₂ from 34.66 ± 0.09 °C to 34.21 ± 0.1 1 °C, resulting in an increase of the thermal resistance from 5.53 ± 0.21 °C/W to 6.18 ± 0.20 °C/W. The effect cannot be reversed by flushing the flow cell with PBS at a flow rate of 0.25 ml/min.

A similar experiment was repeated using a SI P imprinted with PVX viral particles. The results, illustrated in Figures 8 and 9 (the left side thereof) show a similar behavior. Introduction of a solution containing TMV particles does not significantly influence the temperature inside the flow cell (Figure 8) and therefore has no effect on the thermal resistance (Figure 9). Introduction of a solution containing PVX viral particles induces a noticeable decrease in T₂ from 34.36 ± 0.08°C to 33.91 ± 0.12°C and an accompanying increase of the thermal resistance from 5.20 ± 0.28°C to 5.81 ± 0.21 °C. See the right parts of both Figures 8 and 9. Additional flushing with PBS (flow rate 0.25 ml/min) does not seem to affect any of the signals. Example 3: Thermal Wave Transport Analysis (TWTA)

A similar conclusion can be drawn from the TWTA profile.

The results in Figures 6 and 7 illustrate the TWTA response of a TMV-imprinted SIP upon consecutive exposure to a solution containing PVX and TMV viral particles respectively. Addition of PVX particles, followed by flushing with PBS at a flow rate of 0.25 ml/min, does not lead to a noticeable phase shift or decrease in amplitude of the transmitted wave as can be seen in Figures 6 and 7 at the optimal measuring frequency of 0.03 Hz. However, when injecting a solution containing TMV viral particles into the flow cell both a phase shift and a decrease in amplitude can be observed within the transmitted wave. The results, summarized in Figure 7 show a phase shift of 12 ± 0.21 ° at the optimal measuring frequency of 0.03 Hz.

The results in Figures 10 and 1 1 illustrate the TWTA response of a PVX-imprinted SIP upon consecutive exposure to a solution containing TMV and PVX viral particles respectively. Addition of TMV particles, followed by flushing with PBS at a flow rate of 0.25 ml/min, does not lead to a noticeable phase shift or decrease in amplitude of the transmitted wave as can be seen in Figure 10 and 1 1 at the optimal measuring frequency of 0.03 Hz. However, when injecting a solution containing PVX viral particles into the flow cell both a phase shift and a decrease in amplitude can be observed within the transmitted wave. The corresponding phase shift is, as summarized in Figure 1 1 , 1 1 ± 2.9° at the optimal measuring frequency of 0.03 Hz.

Claims

1 . A device (100) for detecting viral particles (132), the device comprising:

a substrate (1 10) having a polymer material (1 12) formed on a surface thereof, the polymer material formulated to bind to the viral particles, wherein a heat transfer property of the polymer material is formulated to vary based on an amount of the viral particles bound thereto;

a heat transfer element (1 14) thermally coupled to a surface of the substrate opposite the polymer material;

a temperature modification device (1 18) thermally coupled to the heat transfer element;

a controller (121 ) configured to cause the temperature modification device to produce a thermal wave (202) emanating from the heat transfer element;

a flow cell (122) located and configured to pass a liquid (124) over the polymer material of the substrate;

a temperature sensor (134) configured to detect a temperature (T₂) of the liquid passing over the polymer material; and

a processor (123) configured to calculate a concentration of viral particles (132) in the liquid based at least in part on a phase shift between the thermal wave at the heat transfer element and an attenuated thermal wave (204) in the liquid.

2. The device of claim 1 , wherein the processor is configured to calculate the

concentration of the viral particles based at least in part on a difference in amplitude between the thermal wave at the heat transfer element and the attenuated thermal wave in the liquid.

3. The device of claim 1 , wherein the substrate comprises a metal or metal alloy.

4. The device of claim 1 , wherein the heat transfer element comprises copper.

5. The device of claim 1 , wherein the controller is configured to change a temperature of the heat transfer element at a variable frequency.

6. The device of claim 1 , wherein the polymer material comprises a viral particle- imprinted polymer, such as a molecularly imprinted polymer or a surface-imprinted polymer.

7. The device of claim 1 , wherein the polymer material comprises a material selected from the group consisting of DNA, RNA, proteins, and portions and analogs thereof.

8. The device of claim 1 , wherein the polymer material is formulated to bind to a first viral particle with a first affinity higher than a second affinity of the polymer material to a second viral particle.

9. The device of claim 8, wherein the first viral particle comprises a first species, and wherein the second viral particle comprises a second species, the second species being an analogue of the first species.

10. A method for detecting viral particles, the method comprising:

passing a liquid (124) containing viral particles (132) over a polymer material (1 12) on a substrate (1 10), the polymer material formulated to bind to the viral particles, wherein a heat transfer property of the polymer material is formulated to vary based on an amount of the virus particles bound thereto;

binding the virus particles to the polymer material;

providing a thermal wave (202) from a heat transfer element (1 14) to the polymer material through the substrate;

detecting a temperature (T₂) of the liquid; and

calculating a concentration of the viral particles in the liquid based at least in part on a phase shift between the thermal wave produced by the heat transfer element and an attenuated thermal (204) wave in the liquid.

1 1 . The method of claim 10, further comprising generating the thermal wave with a controller (121 ) configured to change a temperature (T-i) of a temperature modification device (1 18) thermally coupled to the heat transfer element.

12. The method of claim 10, wherein calculating a concentration of the viral particles in the liquid comprises determining a difference in amplitude between the thermal wave at the heat transfer element and the attenuated thermal wave in the liquid.

13. The method of claim 10, wherein providing a thermal wave from a heat transfer element to the polymer material through the substrate comprises changing a frequency of the thermal wave.

14. The method of claim 10, wherein detecting a temperature of the liquid comprises detecting the temperature of the liquid as a function of time.

15. The method of claim 10, wherein calculating a concentration of the viral particles in the liquid comprises calculating a concentration of a biological viral particles in the liquid.

16. The method of claim 15, wherein calculating a concentration of viral particles in the liquid comprises calculating a concentration of histamine in the liquid.

17. The method of claim 10, wherein passing a liquid containing viral particles over a polymer material on a substrate comprises passing the liquid containing the viral particles over a molecularly imprinted polymer.

18. The method of claim 10, wherein passing a liquid containing viral particles over a polymer material on a substrate comprises passing the liquid containing the viral particles over a material selected from the group consisting of DNA, RNA, proteins, and portions and analogs thereof.

19. The method of claim 10, wherein providing a thermal wave from a heat transfer element to the polymer material through the substrate comprises changing a temperature (T-i) of the heat transfer element by less than 0.2 °C.

The method of claim 10, wherein calculating a concentration of the viral particles the liquid comprises calculating a concentration of viral particles in a mixture comprising a plurality of viral species.

The method of claim 10, further comprising washing the polymer material to remove material other than the viral particles therefrom.

A method of forming a device (100) for detecting viral particles (132), the method comprising:

forming a polymer material (1 12) over a surface of a substrate (1 10), the polymer material formulated to bind to the viral particles, wherein a heat transfer property of the polymer material is formulated to vary based on an amount of the viral particles bound thereto;

thermally coupling a heat transfer element (1 14) to a surface of the substrate opposite the polymer material;

thermally coupling a temperature modification device (1 18) to the heat transfer element;

configuring a controller (120) to cause the temperature modification device to produce a thermal wave (202) emanating from the heat transfer element;

configuring a flow cell (122) to pass a liquid (124) over the polymer material of the substrate;

configuring a temperature sensor (134) to detect a temperature (T₂) of the liquid passing over the polymer material; and

configuring a processor (123) to calculate a concentration of the viral particles (132) in the liquid based at least in part on a phase shift between the thermal wave at the heat transfer element and an attenuated thermal wave (204) in the liquid.

23. The method of claim 22, wherein forming a polymer material over a surface of a substrate comprises screen-printing the polymer material over the surface of the substrate.

24. The method of claim 22 or 23, wherein forming a polymer material over a surface of a substrate comprises forming a molecularly imprinted polymer over the surface of the substrate.

A method for characterizing viral particles, the method comprising:

passing a liquid (124) containing viral particles (132) of a first virus species and a second virus species over and in contact with a polymer material (1 12) on a substrate (1 10), the polymer material formulated to bind to viral particles of the first virus species, wherein a heat transfer property of the polymer material varies based on an amount of the viral particles bound thereto, and wherein the first virus species binds to the polymer material with a higher affinity than the second virus species;

binding a portion of the first virus species and the second virus species to the polymer material;

removing at least a portion of the second virus species from the polymer material;

detecting a temperature of the substrate; and

calculating a concentration of the first virus species in the liquid based at least in part on the temperature of the substrate.

The method of claim 25, wherein the first virus comprises a first species, and wherein the second virus comprises a second species, the second species being an analogue of the first species.

The method of claim 25 or 26, wherein removing at least a portion of the second virus species comprises washing the polymer material.

28. The method of any one or more of the claims 25-27, wherein washing the polymer material comprises rinsing the polymer material with a phosphate buffered saline solution.

29. The method of any one or more of the claims 25-28, wherein passing a liquid

containing the viral particles over a polymer material on a substrate comprises passing the liquid containing the viral particles over an imprinted polymer, such as a molecularly imprinted polymer or a surface-imprinted polymer.

30. The method of any one or more of the claims 25-29, wherein passing a liquid

containing the viral particles over a polymer material on a substrate comprises passing the liquid containing the viral particles over a material selected from the group consisting of DNA, RNA, proteins, and portions and analogs thereof.

31 . The method of any one or more of the claims 25-30, further comprising,

detecting a temperature of the substrate before removing the at least a portion of the second virus species from the polymer material; and

calculating a total concentration of the viral particles in the liquid based at least in part on the temperature of the substrate before removing the at least a portion of the second virus species from the polymer material.

32. The method of any one or more of the claims 25-31 , further comprising detecting a temperature of the liquid, wherein calculating a concentration of viral particles of the first virus species in the liquid is based at least in part on the temperature of the liquid.

33. The method of any one or more of the claims 25-32, further comprising providing a thermal wave from a heat transfer element through the polymer material.

34. The method of claim 33, wherein calculating a concentration of viral particles of the first virus species in the liquid comprises calculating a concentration of viral particles of the first virus species in the liquid based at least in part on a phase shift between the thermal wave produced by the heat transfer element and an attenuated thermal wave having passed through the polymer material.

35. The method of claim 33 or 34, further comprising generating the thermal wave with a controller configured to change a temperature of a temperature modification device thermally coupled to the heat transfer element.

36. The method of any one or more of the claims 33-35, wherein calculating a concentration of the first virus species in the liquid comprises calculating a concentration of the first virus species in the liquid based at least in part on a difference in amplitude between the thermal wave produced by the heat transfer element and the attenuated thermal wave having passed through the polymer material.

37. The method of any one or more of the claims 33-36, wherein providing a thermal wave from a heat transfer element through the polymer material comprises changing a frequency of the thermal wave.

38. The method of any one or more of the claims 33-37, wherein providing a thermal wave from a heat transfer element through the polymer material comprises changing a temperature (T-i) of the heat transfer element by less than 0.2°C.

39. The method of any one or more of the claims 25-32, wherein the step of detecting the temperature of the substrate comprises the steps of

providing heat from a heat transfer element through the substrate;

detecting a first temperature at the side of substrate opposite to the side where the polymer is provided

detecting a second temperature at the side of substrate where the polymer is provided, and

wherein the step of calculating the concentration of the first virus species in the liquid comprises the step of calculating the heat transfer property of the polymer material based on the first and second temperature and the amount of heat being provided by the heat transfer element.

40. A method for characterizing a liquid comprising viral particles, the method

comprising:

passing a liquid (124) containing a first type of viral particles (132a) and at least a second type viral particles (132b) over and in contact with a polymer material (1 12) on a substrate (1 10), the polymer material formulated to bind to the first type of viral particles, wherein a heat transfer property of the polymer material varies based on an amount of material bound thereto, and wherein the first type of viral particles binds to the polymer material with a higher affinity than the at least a second type of viral particles;

binding a portion of the first type of viral particles and a portion of the at least a second type of viral particles to the polymer material;

washing the polymer material to remove the at least a second type of viral particles therefrom;

passing the liquid over the polymer material after washing the polymer material;

washing the polymer material at least a second time to remove the at least a second type of viral particles therefrom;

detecting a temperature of the substrate; and

calculating a concentration of the first type of viral particles in the liquid based at least in part on the temperature of the polymer material.

41 . The method of claim 40, wherein washing the polymer material comprises rinsing the polymer material with a phosphate buffered saline solution.

42. The method of claim 40 or 41 , wherein washing the polymer material to remove the at least a second type of viral particles therefrom comprises removing the at least a second type of viral particles from the polymer material without removing the first type of viral particles from the polymer material.

43. The method of any one or more of the claims 40-42, wherein passing the liquid over the polymer material after washing the polymer material comprises increasing an amount of the first type of viral particles bound to the polymer material.

44. A device (100) for detecting viral particles (132), the device comprising:

a substrate (1 10) having a polymer material (1 12) formed on a surface thereof, the polymer material formulated to bind to the viral particles, wherein a heat transfer property of the polymer material is formulated to vary based on an amount of the viral particles bound thereto; a heat transfer element (1 14) thermally coupled to a surface of the substrate opposite the polymer material;

a controller (121 ) configured to cause the temperature modification device to produce heat emanating from the heat transfer element;

a first temperature sensor configured to detect a first temperature (T-i) at the side of the substrate opposite to the side of the substrate having the polymer material; and

a second temperature sensor configured to detect a second temperature (T₂) of the liquid passing over the polymer material; and

a processor (123) configured to calculate a concentration of viral particles (132) in the liquid based at least in part the temperature difference (T1 -T₂) between the first and second temperatures and the amount of heat emanating from the heat transfer element.

The device of claim 44, wherein the processor is configured to calculate the concentration of the viral particles based at least in part on a difference in amplitude between the thermal wave at the heat transfer element and the attenuated thermal wave in the liquid.

The device of claim 44 or 45, wherein the substrate comprises a metal or metal alloy.

The device of any one or more of the claims 44-46, wherein the heat transfer element comprises copper.

48. The device of any one or more of the claims 44-47, wherein the controller is

configured to maintain a temperature of the heat transfer element constant.

49. The device of any one or more of the claims 44-48, wherein the polymer material comprises a viral particle-imprinted polymer, such as a molecularly imprinted polymer or a surface-imprinted polymer.

50. The device of any one or more of the claims 44-49, wherein the polymer material comprises a material selected from the group consisting of DNA, RNA, proteins, and portions and analogs thereof.

51 . The device of any one or more of the claims 44-50, wherein the polymer material is formulated to bind to a first viral particle with a first affinity higher than a second affinity of the polymer material to a second viral particle.

52. The device of any one or more of the claims 44-51 , wherein the first viral particle comprises a first species, and wherein the second viral particle comprises a second species, the second species being an analogue of the first species.