A stretchable epidermal sweat sensing platform with an integrated printed battery and electrochromic display

Abstract

The lack of compact integration, including fusing of skin-interfaced direct, rapid independent data visualization along with light, safe stretchable batteries, hinders progress towards the creation of fully autonomous comprehensive wearable monitoring platforms. Here we present a highly integrated epidermal sensing platform combining electrochemical sensors with stretchable battery and ultra-low power digital display that instantaneously visualizes the results via 10 individually addressable electrochromic pixels. The all-around stretchable patch can operate independently as a standalone device to directly display the concentration of various electrolytes or metabolites, freeing it from any wired or wireless connection to other equipment. Fabricated via high-throughput printing of customized elastomeric inks, the integrated system presents robust mechanical performance, enduring over 1500 stretching cycles without affecting its sensing and display capabilities. The fast-responding display exhibits stability over 10,000 ON/OFF cycles, and upon coupling with the high-performance stretchable battery, can serve 14,000 sensing sessions in a week-long usage. Merging ultra-low power consumption, independent operation, rapid data display and superior mechanical performance, this fully autonomous multifunctional self-sustainable wearable sensing platform is of high practicality and convenience for diverse practical applications in professional sports, personalized wellness management, and beyond. MainSoft electronics have gathered considerable attention over the past decade as attractive alternatives to their rigid bulky counterparts, for applications in on-body sensing and human-machine interfacing. [1][2][3][4] In particular, many integrated epidermal sensing systems have been developed as "labs-on-the-skin", capable of recording a myriad of mechanical, electrical, physiological, and electrochemical signals, towards applications in healthcare, wellness and tness. [5][6][7][8] The current development of wearable sensors has evolved from the study of physical and chemical sensors alone towards the integration of sensors with energy management, signal acquisition, and data interfacing electronics. 9-14 Due to the lack of high-performance wearable batteries, most wearable electronics currently operate with commercial lithium polymer pouches or coin cells, which are rigid, unsafe, and bottlenecks the product design.Avoiding such battery-related design limitations, conformal epidermal sensors were often designed with wired connections or short-range power delivery schemes, which in turn compromise the system autonomy and limit the user's mobility. 9,11,15−18 Furthermore, such integrated sensors rely on wireless data transmissions, which calls for the need for external devices (e.g., computers, mobile smartphones, customized receivers) for users to obtain the sensing results. 9,11,19−21 Such lack of direct access to sensing results has led to the inconvenience and impracticality of many existing wearable sensors in their rea...

Nonenzymatic Sweat Wearable Uric Acid Sensor Based on N-Doped Reduced Graphene Oxide/Au Dual Aerogels

“…The zero-point energy was calculated by the summation of all vibrational frequencies: (2) where ν corresponds to the vibrational frequency of each normal mode.…”

Wearable E‐Skin Microgrid with Battery‐Based, Self‐Regulated Bioenergy Module for Epidermal Sweat Sensing

“…Fabrication of the Sensors: All sensors were adapted from previous studies. [11,33,34] The carbon electrodes were first printed using the MWCNT ink. The Ag/AgCl reference electrode was printed using the customized stretchable Ag/AgCl ink.…”

“…The printed circuit on SEBS was attached to the fPCB using a solvent-welding process as described in previous studies. [33,35] The power consumption of the circuit was characterized with a constant voltage supply of 1.8 V, and is shown in Figure S4, Supporting Information.…”

“…[11,32] Similarly, the LA sensor was also constructed into a self-powered sensor using NQ-mediated LOx anode and Ag 2 O cathode with an optimized load to provide potentiometric signal corresponding to the lactate concentrations. [33] The selectivity of the sensors has also been tested against common interference found in sweat (Figures S1-S3, Supporting Information). To demonstrate the operation of the system on-body, the sensor patch was placed onto the arm of a subject, and the subject was asked to perform stationary cycling for 45 min followed by 15 min resting (Figure 6E[i]).…”

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