Laser-Induced Graphene-Based Wearable Epidermal Ion-Selective Sensors for Noninvasive Multiplexed Sweat Analysis

Abstract

Wearable sweat sensors are a rapidly rising research area owing to their convenience for personal healthcare and disease diagnosis in a real-time and noninvasive manner. However, the fast and scalable fabrication of flexible electrodes remains a major challenge. Here, we develop a wearable epidermal sensor for multiplexed sweat analysis based on the laser-induced graphene (LIG) technique. This simple and mask-free technique allows the direct manufacturing of graphene electrode patterns on commercial polyimide foils. The resulting LIG devices can simultaneously monitor the pH, Na+, and K+ levels in sweat with the sensitivities of 51.5 mV/decade (pH), 45.4 mV/decade (Na+), and 43.3 mV/decade (K+), respectively. Good reproducibility, stability, and selectivity are also observed. On-body testing of the LIG-based sensor integrated with a flexible printed circuit board during stationary cycling demonstrates its capability for real-time sweat analysis. The concentrations of ions can be remotely and wirelessly transmitted to a custom-developed smartphone application during the period in which the sensor user performs physical activities. Owing to the unique advantages of LIG technique, including facile fabrication, mass production, and versatile, more physiological signals (glucose, uric acid, tyrosine, etc.) could be easily expanded into the LIG-based wearable sensors to reflect the health status or clinical needs of individuals.

Epidermal Wearable Biosensors for Monitoring Biomarkers of Chronic Disease in Sweat

“…Epidermal wearable biosensors have been manufactured on a variety of substrates, such as textiles [ 114 , 123 , 124 , 152 , 155 , 156 ], tattoos [ 40 , 80 , 81 , 93 , 157 ], and patches and bandages [ 149 , 151 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 ].…”

2D-Materials-Based Wearable Biosensor Systems

“…The LIG-based sensors showed good performance, with sensitivities of 51.5 mV/decade (pH), 45.4 mV/decade (Na + ), and 43.3 mV/decade (K + ), and the sensing performance was well-maintained under bent states. Good reproducibility, stability, and selectivity were also observed [ 109 ].…”

A Comprehensive Review of the Recent Developments in Wearable Sweat-Sensing Devices

“…It has led to the generation of extensive attention towards the development of sweat-sensing devices (SSDs) as a diagnostic biofluid. A growing number of research studies that have been reported on analyzing various sweat biomarkers for use in a broad range of clinical diagnostic purposes, including health concerns, nutritional imbalance, drug abuse, and many more [ 1 , 2 , 3 , 4 ], have seen a ten-fold rise in this field, as shown in Figure 1 . However, there are still gaps in the structured content on related SSD applications based on the current existing review articles, such as insufficient information about a few sweat biomarkers, especially hormones, drugs, nicotine, and vitamin C, and inadequate detailed explanation of the respective application concepts related to these biomarkers and a lack of a fundamental response mechanism of chemical sensors that enable users to understand the process of the target analyte’s detection for various sweat compositions [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ].…”