A SENSOR DEVICE

Abstract

A thermistor comprising a functionalised nanoparticle coating bonded thereto, which may be in the form of a nanoscale molecularly imprinted polymer. The thermistor may form part of a device for detecting molecules and a used in a method therefor.

Claims

1. A thermistor comprising a functionalized nanoparticle coating bonded thereto.

2. The thermistor according to claim 1, wherein the coating comprises a nanoscale molecularly imprinted polymer.

3. The sensing device comprising a thermistor according to claim 1 and a resistance measuring device connected to the thermistor.

4. The sensing device according to claim 3, wherein the sensing device comprises the thermistor and at least one additional thermistor.

5. The sensing device according to claim 3, wherein the sensing device is a biomimetic sensor for detecting the presence of biomolecules in a sample.

6. A method of detecting for the presence of a particle comprising the steps of: inserting the thermistor of claim 1 into a sample; monitoring the resistance of the functionalized nanoparticle coated thermistor to identify any change therein when inserted into the sample; and using any change in the resistance of the functionalized nanoparticle coated thermistor to determine the presence of a target molecule.

7. The method according to claim 6, wherein the target molecule is a biomolecule.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which FIG. 1 shows a schematic view of an arrangement according to the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0020] FIG. 1 shows a biomolecule sensing device 10 comprising a thermistor 12 having a functionalised nanoparticle coating 14 bonded thereto in the form of a nanoscale molecularly imprinted polymer. The nanoscale molecularly imprinted polymer 14 is a synthetic receptor and is able to selectively bind to a specific biomolecule 16. The thermistor is connected to a resistance monitoring device 18, in the form of a multimeter or ohmmeter.

[0021] The thermistor 12 is inserted into a sample 20 within a receptacle 22 and the biomolecules 16 therein bind with the nanoscale molecularly imprinted polymer coating 14. The binding of the biomolecules to the thermistor coating insulates the thermistor and so the temperature detected by the thermistor is lower than that of the sample. This induces an electrical resistance within the thermistor that is lower than anticipated, thereby indicating that the biomolecule 16 has bound to the functionalised coating 14. Thus, the biomolecule is detected within the sample 20.

[0022] The coating may be applied to the thermistor in a number of ways.

[0023] In a first method, the thermistor is dip-coated. In this arrangement, the sensitive point of the thermistor is dipped into an aqueous solution of nanoscale molecularly imprinted polymer. The thermistor is subsequently withdrawn at a specific rate with a programmable syringe pump. Subsequently, the thermistor is washed with ethanol to remove excess particles that are not attached to the thermistor and the coated thermistor is left to dry in air. The thermistor is thus functionalised and can be used as described herein.

[0024] In another method, the thermistor is coated in the nanoscale molecularly imprinted polymer using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N-hydroxysuccinimide (NETS)/coupling. In such an arrangement, the nanoscale molecularly imprinted polymer will possess both COOH and NH2 groups, both of which can be used for coupling the polymer to the thermistor. The thermistor is incubated into an EDC/NHS solution and then exposed to the nanoscale molecularly imprinted polymer for two hours. After that period of time, the excess material is washed off with ethanol.

[0025] One arrangement of the present invention employs a negative temperature coefficient thermistor that has the advantage of fast response time and working in a wide temperature range (−40° C. to 125° C.). Such a thermistor comprises a lead wire, which is composed of nickel bifilar and insulated with polyester, that is potted into polyimide tube with a thermally conductive epoxy. Subsequently, the thermistor wires are applied to a nanoscale molecularly imprinted polymer solution in water for 60 seconds and withdrawn at a rate of 5.1 cm min.sup.−1 and the arrangement air dried.

[0026] These functionalised thermistor wires can be inserted into a flow cell, that may be additively manufactured, and that flow cell may be coupled to a thermal device. The flow cell can be sealed off with a copper block that serves as a heat-sink (although other materials may be employed), in which its temperature (T.sub.1) can be steered with a proportional-integral-derivative controller connected to a power resistor, attached to the copper. The thermistor is connected to a printed circuit board. The measured resistance from the functionalised thermistor corresponds to the temperature of the liquid (T.sub.2) at the fixed position in the flow cell. The temperature signal can be measured every second within the flow cell to determine that changes at the interface are due to binding of the biomolecules to the MIP layer, not changes in the temperature within the flow cell. For all measurements, T.sub.1 can be controlled, for example, at 37.00±0.02° C. in order to mimic biological conditions. A sample to be tested can be placed in, or directed through, the flow cell and the resistance of the thermistor measured accordingly. It may be desirable to place a thermocouple within the flow cell to monitor the properties of the sample, such as its temperature.

[0027] Whilst the present invention may be undertaken using negative temperature coefficient or positive temperature coefficient thermistors, it is preferable to use a negative temperature coefficient thermistor to increase the resistance of the thermistor upon the decrease of detected temperature.

[0028] Preferably, the thermistor is particularly sensitive in the range between 20° C. and 37° C., which is especially useful for detecting biomolecules. Compared with thermocouples, thermistors have smaller dimensions, lower cost and higher sensitivity over a specific temperature range, thereby giving significant benefits over the use of thermocouples.

[0029] It will be appreciated that some thermistors are provided with a protective polyimide coating that may have to be removed prior to the application of the functionalised coating.

[0030] The thermistor may be connected to a printed circuit board and further elements may be applied to the printed circuit board, such as a processor and/or a specialised resistance meter. The printed circuit board may be particularly advantageous where a plurality of thermistors is incorporated into a system.

[0031] Flow cells may be provided into which samples to be tested can be provided. The thermistor can be readily inserted into such flow cells to determine if the predetermined molecule is present therein.

[0032] It is envisaged that in some circumstances, the binding of molecules to the nanoscale molecularly imprinted coating may increase the thermal conductivity of the thermistor, rather than decrease. In such a situation, it may be desirable to employ a positive temperature coefficient thermistor and/or to adapt the arrangement and processing of the signal accordingly.

[0033] The present invention may be used to identify small molecules, proteins or bacteria.

[0034] The arrangement of the present invention results in a more accurate detection of molecules at a reduced cost over existing systems that employ thermocouples. Furthermore, the present invention is able to be obtain in sample, or in vivo, measurements, which can assist with providing real-time indications of the presence of molecules, particularly biomolecules, including biomarkers.