Electrical Activation of Microelectro-Mechanical (MEM) Systems for Electrochemical and Thermomechanical Measurements

Abstract

Microelectro-mechanical (MEM) systems offer unique opportunities for miniaturized sensing platforms, yet their application in electrochemical measurements is often limited by the insulating nature of silicon and polymer coatings. In this work, a versatile activation strategy combining electrothermal (ET) reorientation and charged gas activation (CA) plasma treatments is applied to both pristine and poly(lactic acid) (PLA)-coated silicon MEM systems to enable multifunctional electrochemical and thermomechanical performance. The effect of ET reorientation, CA, and combined ET+CA treatments on the properties was systematically investigated. For uncoated MEM systems, CA and ET+CA significantly enhanced the surface wettability and electrochemical activity, leading to increased capacitive charge storage. While CA yielded the highest charge capacity, ET+CA provided a balanced improvement in the electrochemical performance and stability. In PLA-coated MEMs, the polymer layer acted as an insulating and protective coating, reducing electroactivity but improving stability; nevertheless, plasma-based treatments partially restored the electrochemical functionality. As a proof of concept, ET+CA-treated MEM systems demonstrated an enhanced dopamine detection. Thermomechanical analyses further revealed that PLA-coated MEM functions as sensitive biomaterial sensors, enabling the detection of glass transition and cold crystallization of PLA. Overall, the ET+CA approach transforms insulating MEM platforms into electro-responsive and thermomechanically sensitive devices suitable for advanced sensing applications.