Stretchable, Multifunctional Epidermal Sensor Patch for Surface Electromyography and Strain Measurements

Abstract

The concurrent collection of surface electromyography (sEMG) and strain signals is important for many applications, such as human–machine interaction, sign language recognition, and clinical evaluation of muscle function. Nevertheless, the conventional sensor systems made of rigid, bulky components cannot provide a reliable, conformal interface for accurate, continuous measurements of the epidermal physiological signals. Herein, a skin‐interfaced, multifunctional epidermal sensor patch with characteristics of mechanical softness, large stretchability, and wearable conformability for multimodal measurements of sEMG signals and associated skin deformations from various muscle activities and joint motions is reported. The sensor patch features two pairs of stretchable sEMG electrodes and two thin, miniaturized strain sensors, which are connected by stretchable filamentary serpentine interconnects in an open‐meshed structure. Experimental and computational studies reveal the design and operation of the sensor patch, which exhibit stable and repetitive performance even under a 30% stretching strain level. Demonstrations of the sensor patch on the wrist for simple sign language recognition and on the lower back for the flexion‐relaxation phenomenon illustrate its potential for the comprehensive assessment of the muscle activities and related motions of muscle joints.

Flexible Sensory Systems: Structural Approaches

“…Due to this deformation, the interconnect can have a stretchability that does not break, even in tension. Currently, stretchable interconnects are being manufactured using patterns such as serpentine and fractal designs [ 7 , 14 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ]. The most representative pattern in stretchable interconnects is the former [ 84 , 94 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ], in which two semicircles are repeatedly connected in a straight line.…”

“…Interconnects with improved stretchability through pattern design are being used in various fields, such as wearable devices and biomonitoring [ 14 , 96 , 97 , 98 , 99 , 100 , 101 ]. The device shown in Figure 3 d has improved stretchability, with a serpentine pattern interconnect [ 96 ]. This device was attached to the skin and utilized for human monitoring.…”

“…Stretchable interconnects are used in various fields, such as wearable devices and bioelectronics [ 96 , 97 , 112 , 126 ]. A stretchable interconnect structure is essential in the field of soft electronics, because it has a structure that facilitates the connection of components of the sensor.…”

High Channel Temperature Mapping Electronics in a Thin, Soft, Wireless Format for Non-Invasive Body Thermal Analysis

“…As a result, the temperatures of 80 subdivided regions on the target area could be measured simultaneously. Furthermore, to increase the resolution of the temperature mapping system, the gaps among each thermistor in the array were minimized by adopting a straight-line design of the conductive layer in the sensing panel [ 86 , 87 ]. According to the data collected, the location of a specific blood vessel and its flow direction can be analyzed at the same time.…”

Thermal Analysis on Active Heat Dissipation Design with Embedded Flow Channels for Flexible Electronic Devices

“…In recent years, electronic products have emphasized intelligence and miniaturization, which require higher performance at the integration level. In particular, flexible electronic devices represent a rapidly developing branch, which has enabled many new applications such as curvilinear electronics and bio-integrated electronics [1][2][3][4][5][6] due to their unique advantages of stretchability and flexibility [7][8][9][10]. Furthermore, hybrid flexible systems have been investigated, such as electrophysiology [11], multimodal [12], large-area pressure [13] and other functions [14]; such functions may lead to overheating in the system.…”