Parylene C-Based Flexible Electronics for pH Monitoring Applications

Abstract

Emerging materials in the field of implantable sensors should meet the needs for biocompatibility; transparency; flexibility and integrability. In this work; we present an integrated approach for implementing flexible bio-sensors based on thin Parylene C films that serve both as flexible support substrates and as active H+ sensing membranes within the same platform. Using standard micro-fabrication techniques; a miniaturized 40-electrode array was implemented on a 5 μm-thick Parylene C film. A thin capping film (1 μm) of Parylene on top of the array was plasma oxidized and served as the pH sensing membrane. The sensor was evaluated with the use of extended gate discrete MOSFETs to separate the chemistry from the electronics and prolong the lifetime of the sensor. The chemical sensing array spatially maps the local pH levels; providing a reliable and rapid-response (<5 s) system with a sensitivity of 23 mV/pH. Moreover; it preserves excellent encapsulation integrity and low chemical drifts (0.26–0.38 mV/min). The proposed approach is able to deliver hybrid flexible sensing platforms that will facilitate concurrent electrical and chemical recordings; with application in real-time physiological recordings of organs and tissues.

Biorealistic cardiac cell culture platforms with integrated monitoring of extracellular action potentials

“…Other approaches such as micro-stamping and microfluidic patterning, require special consideration when aligning the pattern with the active electrode array, and usually require special equipment (alignment stage) to ensure precise and repeatable patterning of the MEA surface 16 . Our technique can also deliver flexible MEA platforms, since Parylene’s excellent mechanical and thermal properties enable the production of high-density MEAs on free-standing thin (down to 1 μm) flexible films 43 for a more thorough investigation of the role of the ECM stiffness in cellular function. Finally, the proposed methodology yields MEA platforms that are easy and simple to use, as the ECM compounds (fibronectin or collagen) and cells self-assemble after random plating.…”

Microfabricated electrochemical pH and free chlorine sensors for water quality monitoring: recent advances and research challenges

“…137 The resulting pH sensitivity of 23 mV per pH in the pH range of 4 to 10 was relatively low. Parylene-C, one of the few examples, was treated with oxygen plasma to generate surface functional groups for H 3 O + binding.…”

An Overview of the Development of Flexible Sensors

“…Flexible capacitance‐modulated sensors can have their sensing layers deposited directly on top of their dielectric layers or as extended gates. Flexible extended‐gate, capacitance‐modulated sensors have been demonstrated by making use of pH‐sensitive Parylene‐C, amorphous IGZO, and roll‐roll RF sputtered ITO films deposited on plastic substrates. Notably, in such devices, only the sensing extended gate is flexible, whereas the rest of the device is not.…”