A sensor chip (110, 210) comprising: a force-responsive component (120, 220), having a mass component and a spring component and a resonant frequency and being configured and arranged to move in response to an applied force in accordance with a spring constant that is susceptible to fluctuation, and; a circuit configured and arranged to determine Brownian motion of the force-responsive component at the resonant frequency based on temperature, and to generate an output based on the determined Brownian motion and movement of the force-responsive component, the output being indicative of force applied to an apparatus, wherein the circuit includes a displacement detector (130, 230) configured and arranged to provide a voltage output that characterizes the applied force and that varies based upon the applied force and fluctuations in the spring constant, a temperature sensor, a reference circuit including at least one of a capacitance, resistance and voltage source, and a spectrum analyzer having a fixed amplitude and frequency range, the circuit being configured and arranged to detect displacement of the force-responsive component using the at least one of a capacitance, resistance and voltage source, estimate Brownian motion noise based on an output of the spectrum analyzer indicative of a Brownian motion-based peak in resonance of the voltage output, use the estimated Brownian motion noise and temperature detected by the temperature sensor to determine a value of the spring constant, and generate the output by determining pressure applied to the force-responsive component, based on the determined value of the spring constant and the detected displacement. a force-responsive component (120, 220), having a mass component and a spring component and a resonant frequency and being configured and arranged to move in response to an applied force in accordance with a spring constant that is susceptible to fluctuation, and; a circuit configured and arranged to determine Brownian motion of the force-responsive component at the resonant frequency based on temperature, and to generate an output based on the determined Brownian motion and movement of the force-responsive component, the output being indicative of force applied to an apparatus, wherein the circuit includes a displacement detector (130, 230) configured and arranged to provide a voltage output that characterizes the applied force and that varies based upon the applied force and fluctuations in the spring constant, a temperature sensor, a reference circuit including at least one of a capacitance, resistance and voltage source, and a spectrum analyzer having a fixed amplitude and frequency range, the circuit being configured and arranged to detect displacement of the force-responsive component using the at least one of a capacitance, resistance and voltage source, estimate Brownian motion noise based on an output of the spectrum analyzer indicative of a Brownian motion-based peak in resonance of the voltage output, use the estimated Brownian motion noise and temperature detected by the temperature sensor to determine a value of the spring constant, and generate the output by determining pressure applied to the force-responsive component, based on the determined value of the spring constant and the detected displacement. detect displacement of the force-responsive component using the at least one of a capacitance, resistance and voltage source, estimate Brownian motion noise based on an output of the spectrum analyzer indicative of a Brownian motion-based peak in resonance of the voltage output, use the estimated Brownian motion noise and temperature detected by the temperature sensor to determine a value of the spring constant, and generate the output by determining pressure applied to the force-responsive component, based on the determined value of the spring constant and the detected displacement.