A device for sensing particles in a sample, wherein the particles may be atoms, molecules, compounds or particulate matter, the device comprising: a sensor comprising: a bulk acoustic wave resonator having a resonant frequency; an acoustic mirror arranged to support the resonator; and a heater in thermal communication with the resonator such that a resonator temperature is based on a heater temperature; circuitry connected to the sensor, wherein the circuitry comprises: a driver configured to drive the heater with a driver signal having a constant periodic cycle; an oscillator configured to generate an output signal indicative of the resonant frequency, wherein the resonant frequency is modulated by the resonator temperature such that the resonant frequency has a periodic cycle; and a processor configured to determine particle composition and/or concentration of the sample based on the output signal; wherein determining particle composition and/or concentration comprises: performing a transform on a signal received by the processor that is indicative of the output signal; generating a frequency-domain signal based on the received signal, wherein the frequency domain signal has first and second peaks corresponding to first and second resonator temperatures respectively; and determining a frequency shift between the first and second peaks and/or determining the amplitude of the first and second peaks. a sensor comprising: a bulk acoustic wave resonator having a resonant frequency; an acoustic mirror arranged to support the resonator; and a heater in thermal communication with the resonator such that a resonator temperature is based on a heater temperature; a bulk acoustic wave resonator having a resonant frequency; an acoustic mirror arranged to support the resonator; and a heater in thermal communication with the resonator such that a resonator temperature is based on a heater temperature; circuitry connected to the sensor, wherein the circuitry comprises: a driver configured to drive the heater with a driver signal having a constant periodic cycle; an oscillator configured to generate an output signal indicative of the resonant frequency, wherein the resonant frequency is modulated by the resonator temperature such that the resonant frequency has a periodic cycle; and a processor configured to determine particle composition and/or concentration of the sample based on the output signal; a driver configured to drive the heater with a driver signal having a constant periodic cycle; an oscillator configured to generate an output signal indicative of the resonant frequency, wherein the resonant frequency is modulated by the resonator temperature such that the resonant frequency has a periodic cycle; and a processor configured to determine particle composition and/or concentration of the sample based on the output signal; wherein determining particle composition and/or concentration comprises: performing a transform on a signal received by the processor that is indicative of the output signal; generating a frequency-domain signal based on the received signal, wherein the frequency domain signal has first and second peaks corresponding to first and performing a transform on a signal received by the processor that is indicative of the output signal; generating a frequency-domain signal based on the received signal, wherein the frequency domain signal has first and second peaks corresponding to first and second resonator temperatures respectively; and determining a frequency shift between the first and second peaks and/or determining the amplitude of the first and second peaks.