Dynamic in Vitro Biosensing with Flexible Microporous Multimodal Cell-Interfacial Sensors

This work presents a new porous membrane-based approach towards designing biosensors for in vitro bio microsystems. Compared to standard microfluidic sensor systems, cell molecular release can be more directly measured by interfacial sensors fabricated directly on tissue culture membranes. Cell-released molecules need only diffuse through micro-sized pores for detection at sensors fabricated on the bottom of the membrane, allowing detection at higher concentrations and at timescales closer to native cell-release. We present a membrane-integrated cyclic voltammetry (CV) sensor with a carbon nanotube- (CNT) modified working electrode for selective sensing of neurotransmitter serotonin (5-HT). We achieve dynamic, concentration-dependent 5-HT sensing with a linear range of 0.5-10μM (r
²
= 0.934) and sensitivity of ~200μA/μM measured in cell media and cell supernatant. The membrane also supports cell-interfacial impedance electrodes to monitor physical cell coverage, demonstrating multimodal cellular and molecular sensing. This flexible substrate can be adapted in the future for sensing of further in vitro or in vivo bio-microsystems.