Method for Detecting an Analyte Using Electromagnetic Radiation

1 . A method for detecting an analyte in a sample using electromagnetic radiation comprising:

(i) providing a labelled reagent, the labelled reagent having a binding site which is capable of binding the analyte or an analogue of the analyte and a label, wherein the label is capable of absorbing the electromagnetic radiation to generate energy by non-radiative decay;

(ii) providing a device having

a radiation source adapted to generate a series of pulses of electromagnetic radiation,

a transducer having a pyroelectric or piezoelectric element and electrodes, which is capable of transducing energy generated by non-radiative decay into an electrical signal,

a detector which is capable of detecting the electrical signal,

a controller for controlling the source of electromagnetic radiation and the detector,

wherein the device has a first and second chamber,

the first chamber containing a first reagent proximal to the transducer, wherein the first reagent is capable of binding to the analyte such that the binding of the labelled reagent to the first reagent via the analyte is directly proportional to the concentration of the analyte, and

the second chamber containing a second reagent proximal to the transducer, wherein the second reagent mimics the analyte such that the binding of the labelled reagent to the second reagent is inversely proportional to the concentration of the analyte;

(iii) exposing the sample to the transducer;

(iv) irradiating the sample with electromagnetic radiation and detecting the electrical signal.

2 . A method as claimed in claim 1 , wherein the device further comprises a third chamber comprising a third reagent proximal to the transducer, the third reagent having a lower affinity for the analyte or the labelled reagent under the conditions of the assay than the first reagent for the analyte.

3 . A method as claimed in claim 1 , wherein the binding of the first and second reagents to the analyte or the labelled reagent is dependent on the analyte concentration and the binding of the third reagent to the analyte or the labelled reagent is independent of analyte concentration.

4 . A method as claimed in claim 1 , wherein the third reagent has essentially no affinity for the analyte or the labelled reagent under the conditions of the assay.

5 . A method as claimed in claim 1 , wherein the first, second and third reagents are attached to the transducer via non-covalent bonding.

6 . A method as claimed in claim 1 , wherein the first reagent is an antibody and the analyte is an antigen.

7 . A method as claimed in claim 1 wherein the labelled reagent is a labelled antibody.

8 . A method as claimed in claim 1 wherein the labelled reagent comprises a label, wherein the label is selected from a dye molecule, a gold particle, a coloured-polymer particle, a fluorescent molecule, an enzyme, a red blood cell, a haemoglobin molecule, a magnetic particle and a carbon particle.

9 . A method as claimed in claim 1 , wherein the method is carried out without removing the sample from the transducer between the steps of exposing the sample to the transducer and irradiating the sample.

10 . A kit comprising the device and the labelled reagent, as claimed in claim 1 .