A programmable epidermal microfluidic valving system for wearable biofluid management and contextual biomarker analysis

Haisong Lin,Shuyu Lin,Siyang Yang,Christopher Yeung,Hannaneh Hojaiji,Xuanbing Cheng,Zhaoqing Wang,Sam Emaminejad,Bo Wang,Jialun Zhu,Jiawei Tan,Wenzhuo Yu,Yichao Zhao,Eric Tang

doi:10.1038/s41467-020-18238-6

Abstract

Active biofluid management is central to the realization of wearable bioanalytical platforms that are poised to autonomously provide frequent, real-time, and accurate measures of biomarkers in epidermally-retrievable biofluids (e.g., sweat). Accordingly, here, a programmable epidermal microfluidic valving system is devised, which is capable of biofluid sampling, routing, and compartmentalization for biomarker analysis. At its core, the system is a network of individually-addressable microheater-controlled thermo-responsive hydrogel valves, augmented with a pressure regulation mechanism to accommodate pressure built-up, when interfacing sweat glands. The active biofluid control achieved by this system is harnessed to create unprecedented wearable bioanalytical capabilities at both the sensor level (decoupling the confounding influence of flow rate variability on sensor response) and the system level (facilitating context-based sensor selection/protection). Through integration with a wireless flexible printed circuit board and seamless bilateral communication with consumer electronics (e.g., smartwatch), contextually-relevant (scheduled/on-demand) on-body biomarker data acquisition/display was achieved.

Highlights

Active biofluid management is central to the realization of wearable bioanalytical platforms that are poised to autonomously provide frequent, real-time, and accurate measures of biomarkers in epidermally-retrievable biofluids
To render active biofluid management in a wearable format, here, we devise an electronically programmable microfluidic valving system, which is capable of biofluid sampling, routing, and compartmentalization for biomarker analysis
The active fluid control achieved by this system is harnessed to create new wearable bioanalytical capabilities at both the sensor and system levels

Summary

Introduction

Active biofluid management is central to the realization of wearable bioanalytical platforms that are poised to autonomously provide frequent, real-time, and accurate measures of biomarkers in epidermally-retrievable biofluids (e.g., sweat). These sensors rely on the analysis of biofluid samples that are passively collected in predefined microfluidic structures to minimize evaporation[4,5,6,14,15] Their lack of active control on biofluid flow fundamentally renders them (1) susceptible to operationally relevant confounders such as flow rate variability, (2) incapable of performing diverse bioanalytical operations (e.g., incubation), and (3) incapable of delivering programmable biofluid management functionalities (e.g., biofluid routing and compartmentalization) that are critical to the operational autonomy of the envisioned systems, such as capturing biomarker readings at contextually relevant timepoints. These capabilities can be positioned to render context-based sensor selection/protection, where the mode of analysis will be selected depending on the user’s need, behavior, and activity

Methods

Results

Conclusion