A method for detecting an analyte in a sample, comprising the steps of: exposing the sample to a transducer which is capable of transducing a change in energy to an electrical signal and which comprises a pyroelectric or piezoelectric transducer having a pyroelectric or piezoelectric element and electrodes, the transducer comprising polyvinylidene fluoride and indium tin oxide, the transducer also having at least one tethered reagent on or proximal thereto, the at least one tethered reagent having a binding site which is capable of binding the analyte; introducing a labelled reagent into the sample, wherein the labelled reagent contains a binding site for the analyte or the tethered reagent and a label which is capable of absorbing electromagnetic radiation generated by a radiation source to generate energy by non-radiative decay, wherein the label is selected from a metal particle, a coloured-polymer particle, a magnetic particle, a carbon particle and a nanoparticle comprising a non-conducting core material and at least one metal shell layer; allowing the labelled reagent to bind to the analyte or tethered reagent in a first period in which the transducer is oriented such that the labelled reagent is caused to settle, at least in part, on the transducer; subsequently, in a second period, causing the labelled reagent to become unsettled by inverting the transducer with respect to the sample or partially inverting the transducer with respect to the sample such that the labelled reagent is caused to move away from the transducer surface; irradiating the sample with electromagnetic radiation during the first and second periods, transducing the energy generated into an electrical signal; detecting the electrical signal. exposing the sample to a transducer which is capable of transducing a change in energy to an electrical signal and which comprises a pyroelectric or piezoelectric transducer having a pyroelectric or piezoelectric element and electrodes, the transducer comprising polyvinylidene fluoride and indium tin oxide, the transducer also having at least one tethered reagent on or proximal thereto, the at least one tethered reagent having a binding site which is capable of binding the analyte; introducing a labelled reagent into the sample, wherein the labelled reagent contains a binding site for the analyte or the tethered reagent and a label which is capable of absorbing electromagnetic radiation generated by a radiation source to generate energy by non-radiative decay, wherein the label is selected from a metal particle, a coloured-polymer particle, a magnetic particle, a carbon particle and a nanoparticle comprising a non-conducting core material and at least one metal shell layer; allowing the labelled reagent to bind to the analyte or tethered reagent in a first period in which the transducer is oriented such that the labelled reagent is caused to settle, at least in part, on the transducer; subsequently, in a second period, causing the labelled reagent to become unsettled by inverting the transducer with respect to the sample or partially inverting the transducer with respect to the sample such that the labelled reagent is caused to move away from the transducer surface; irradiating the sample with electromagnetic radiation during the first and second periods, transducing the energy generated into an electrical signal; detecting the electrical signal.