Fully Stretchable Capillary Microfluidics-Integrated Nanoporous Gold Electrochemical Sensor for Wearable Continuous Glucose Monitoring

Abstract

Biosensor systems for wearable continuous monitoring are desired to be developed into conformal patch platforms. However, developing such patches is very challenging owing to the difficulty of imparting materials and components with both high stretchability and high performance. Herein, we report a fully stretchable microfluidics-integrated glucose sensor patch comprised of an omnidirectionally stretchable nanoporous gold (NPG) electrochemical biosensor and a stretchable passive microfluidic device. A highly electrocatalytic NPG electrode was formed on a stress-absorbing 3D micropatterned polydimethylsiloxane (PDMS) substrate to confer mechanical stretchability, high sensitivity, and durability in non-enzymatic glucose detection. A thin, stretchable, and tough microfluidic device was made by embedding stretchable cotton fabric as a capillary into a thin polyurethane nanofiber-reinforced PDMS channel, enabling collection and passive, accurate delivery of sweat from skin to the electrode surface, with excellent replacement capability. The integrated glucose sensor patch demonstrated excellent ability to continuously and accurately monitor the sweat glucose level.

Stretchable Sensors for Nanomolar Glucose Detection

“…The achieved LOD is lower than those reported for electrodes utilizing structures with nanoparticles of gold, platinum, or other alloy combinations with carbon,10,30,31 as well as for nanoporous substrates and electrodes functionalized with glucose oxidase 32–37. Table S3 (Supporting Information) compares the figures of merit obtained in this paper with other published works investigating flexible, glucose sensors.…”

Advanced Wearable Microfluidic Sensors for Healthcare Monitoring

“…f) Schematic illustration of the nonenzymatic electrochemical biosensor (right), and optical images of the sensor attached to an arm and the electrodes applied in this biosensor (left). Reproduced with permission . Copyright 2019, American Chemical Society.…”

“…However, during long‐term detection, the enzymes immobilized on the working electrodes will not recover their original characteristics, influenced by the surrounding conditions, such as the temperature and pH level, which affects the sensitivity and stability for continuous monitoring . To address this limitation, Bae et al presented a nonenzymatic electrochemical biosensor for glucose monitoring (Figure f) . This sensor utilizes an electrocatalytic nanoporous gold electrode as the working electrode, exhibiting great sensitivity to glucose (253.4 µA cm −2 mM −1 ) and no degradation under 30% strain.…”

Reusable, Non-Invasive, and Ultrafast Radio Frequency Biosensor Based on Optimized Integrated Passive Device Fabrication Process for Quantitative Detection of Glucose Levels

“…A biosensor can convert different concentrations of glucose into corresponding electrical signals for output, which has advantages of high accuracy, fast analysis, low cost, good repeatability, simple operation and high specificity by comparing with traditional detection methods [10][11][12][13][14][15][16]. With the aid of chips, microfluidics systems and labs-on-a-chip, biosensor technology have developed rapidly and can be divided into electrochemical biosensors and optical biosensors based on the type of signal conversion [17][18][19][20][21][22][23][24][25][26]. Electrochemical biosensors enable the detection of biomarkers by adding specific enzymes on the electrodes, which has many advantages, such as high sensitivity, simple operation and cost-effective [27][28][29].…”