Dual-Gate Fet-Based Charge Sensor Enhanced by In-Situ Electrode Decoration in a MEMS Organs-On-Chip Platform

Continuous monitoring of tissue microphysiology is a key enabling feature of the organ-on-chip (OoC) approach for drug screening and disease modeling. Sensing charged species in OoC tissue microenvironments is thereby essential. However, the inherently small (i.e., cm) size of OoC devices poses the challenging requirement to integrate miniaturized and highly sensitive in situ charge sensing components to maximize signal extraction from small volumes (nL to µL, range) of media used in these devices. Here we meet this need by presenting a novel dual-gate field-effect transistor-based charge sensor integrated within an optically transparent microelectromechanical (MEM) OoC device. Post-process mask-less decoration of Ti sensing electrodes by spark-ablated Au nanoparticle films significantly increases the effective electrode surface area and thus sensor sensitivity while retaining the CMOS-compatibility of the wafer-level fabrication process. We validate the biocompatibility of the sensor and its selective response to poly-D-lsine and KC1, and provide a perspective on monitoring cultures and differentiation of hiPSC-derived cortical neurons on our OoC device.

Introduction

Organs-on-chip (OoCs) are dynamic tissue culture devices which mimic microphysiological environments to recapitulate in vivo-like organ functions in vitro and thus enhance the efficiency of drug development and disease modelling [1]. Among the key features distinguishing OoCs from established tissue culture technologies, automated monitoring of biological cues, such as charged species, is essential to reduce user intervention and improve system's ease of use and reliability [2]. In this respect, dynamic electric sensing can meet user needs without recurring to terminal optical labeling and microscopy techniques, which deteriorate cells' wellbeing.