we want to measure changes and response times in capacitance when sensor exposed to desired gas. LCR meter and impedance spectroscopy are not options. help with practical circuit for the measurement.
A MEMS sensor has been developed for use as a calorimetric cell in an ultra-sensitive, thin-film, differential scanning calorimetric technique. The sensor contains a freestanding, thin (30 nm to 1000 nm), low-stress silicon nitride membrane with lateral dimensions of a few millimeters. This membrane, along with a thin (50 nm) metallization layer, forms a calorimetric cell with an exceptionally small addenda. This small addenda creates a very sensitive calorimetric cell, able to make heat capacity measurements of nanometer-thick metal and polymer films. The sensor fabrication and various design considerations are discussed in detail. The calorimetric technique and examples of applications are described.
The standard method to do this, is:
1. Make the capacitor whose value you want to measure part of a resonant circuit, the second element being a high-quality inductor or X-tal.
2. Build an oscillator with this resonant circuit.
3. Measure the frequency.
Some examples of oscillator circuits are here :
https://modernhamguy.com/osc-i-1-lc-oscillators/
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