A novel sensing mechanism for electrostatic MEMS that employs static bifurcation-based sensing and binary detection is demonstrated. It is implemented as an ethanol vapour sensor that exploits the static pull-in bifurcation. Sensor detection of 5 ppm of ethanol vapour in dry nitrogen, equivalent to a detectable mass of 165 pg, is experimentally demonstrated. Sensor robustness to external disturbances is also demonstrated. A closed-form expression for the sensitivity of statically detected electrostatic MEMS sensors is derived. It is shown that the sensitivity of static bifurcation-based binary electrostatic MEMS sensors represents an upper bound on the sensitivity of static detection for given sensor dimensions and material properties.

A novel electrostatic MEMS gas sensor is demonstrated. It employs a dynamic-bifurcation detection technique. The sensor detects ethanol vapor in a binary mode, reporting ON-state (1) for concentrations above a preset threshold and OFF-state (0) for concentrations below the threshold. The sensing mechanism exploits the qualitative difference between the sensor state before and after the dynamic pull-in bifurcation. Experimental demonstration was carried out using a laser Doppler vibrometer to measure the sensor response before and after detection. The sensor was able to detect ethanol vapor concentrations as 100 ppb in dry nitrogen. A closed-form expression for the sensitivity of dynamic bifurcation sensors was derived. It captures the dependence of sensitivity on the sensor dimensions, material properties, and electrostatic field.

This paper offers a critical overview of recent advancements in aqueous sensors for heavy metals. The paper focuses on the challenges and advantages of using microelectromechanical systems (MEMS) sensors in aqueous environments, as well as technical considerations for choosing appropriate polymeric sensing materials. In addition, general considerations and recommendations are included for developing MEMS chemical sensors. These considerations centre around the chemical nature of the target analyte and the environment of the sensor application. By following these recommendations and taking the time to design a suitable sensor and sensing material for the target application instead of a trial‐and‐error approach, it is possible to save both time and cost.

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