A Bilayer Microfluidics-Based Elastic Encapsulation Method of Liquid Metal Circuits with Cellular Resolution

Abstract

Mechanical mismatches at the microscale between bioelectronics and cells severely hinder the successful acquisition of high-quality and stable electrophysiological signals. Room-temperature liquid metals (EGaIn), which possess a near-zero Young's modulus, present a promising material for achieving stable conformal contact with biological tissues. However, the fluidity of liquid metals limits the elastic encapsulation of the patterned circuits with cellular resolution. To address this challenge, we develop a bilayer microfluidics-based method to elastically encapsulate a high-resolution electrode array (20 μm) within several minutes (<3 min). The alignment-free method overcomes the limitations of packaging polymers and high-resolution aligners, enabling cost-effective, scalable manufacturing for devices. These electronics exhibit excellent wear resistance, high flexibility (>300% strain), and excellent biocompatibility, facilitating long-term stable interfacing with cardiomyocytes and enabling the collection of high-quality (∼30 dB) cell field potential signals as well as epicardial signals (∼42 dB) from living rat models. This rapid and straightforward encapsulation approach improves the precision and integration of liquid metal-based flexible electronics, holding the promise of high-resolution monitoring and treatment, such as electrophysiological mapping, electrical stimulation, and other therapeutic interventions at the cellular levels.