The present invention relates to a method for detecting an analyte (10) in a sample, comprising the steps of: providing a transducer (3) having a pyroelectric or piezoelectric element and electrodes which is capable of transducing a change in energy to an electrical signal, a first reagent (9) immobilised on the transducer, the first reagent having a binding site which is capable of binding the analyte or a derivative of the analyte, exposing the sample to the transducer thereby allowing the analyte or a derivative of the analyte to bind to the first reagent to form a first reagent-analyte complex (13); introducing a second reagent (11), the second reagent having a binding site which is capable of selectively binding the first reagent-analyte complex, wherein the second reagent has a label (12) attached thereto which is capable of absorbing electromagnetic radiation to generate energy by non-radiative decay; irradiating the sample with electromagnetic radiation; transducing the energy generated into an electrical signal; and detecting the electrical signal. The invention also provides a kit for carrying out the method.