Advances in Rational Design and Materials of High‐Performance Stretchable Electromechanical Sensors

Abstract

curved surfaces and deformed objects. [5,6] An effective solution is using stretchable intrinsic materials and stretchable structural designs to form mechanical sensors. [7,8] Compared to conventional rigid sensors, it is desirable for stretchable sensors to provide mechanical robustness, biocomparability, multifunctionality, as well as comfort of wearing such sensors. [9,10] Stretchable electromechanical sensors are capable of being comfortably attached on the human body and skin and perceiving mechanical stimuli. These sensors have huge potential applications in personal healthcare, including detection of human motion/gesture, breath, and pulse monitoring. Stretchable electromechanical sensors have recently attracted great interest due to their high sensitivity, stretchability, simplicity in design, and implementation. Compared with the other kinds of sensors, for example, stretchable piezoelectric/triboelectric sensors, electromechanical sensors usually require supply power or battery.A stretchable sensor typically consists of a sensing block embedded or integrated into a stretchable substrate that can be elongated under application of mechanical stimuli. [11,12] The sensing block acts as a mechanical sensing unit, which for instance converts stress/strain into a measurable electrical signal. The presence of nanomaterials and composites in the sensing block has been utilized as a preferable design for stretchable sensors. [11,13] Selection criteria of these materials include structural stretchability, suitable conductivity, and high mechanical strength. Designing the sensing structure aims for high sensitivity, fast response, linearity, and a wide working range. [14,15] The integration of nanomaterials and nanocomposites into stretchable sensors are currently an emerging trend of wearable sensors in their research, development, and commercialization. [10,11] The development of stretchable sensors with low power consumption for portable applications is also of great interest. [16,17] The conventional design method for "partly stretchable" sensing devices integrates "hard" sensors and "soft" interconnects to form "island-interconnect" configurations. [18,19] This approach deploys an isolated island to carry the rigid sensors and a stretchable network of interconnections. Geometric engineering structures including serpentine and fractal designs have been widely employed, to achieve stretchability Stretchable and wearable sensor technology has attracted significant interests and created high technological impact on portable healthcare and smart human-machine interfaces. Wearable electromechanical systems are an important part of this technology that has recently witnessed tremendous progress toward high-performance devices for commercialization. Over the past few years, great attention has been paid to simultaneously enhance the sensitivity and stretchability of the electromechanical sensors toward high sensitivity, ultra-stretchability, low power consumption or selfpower functionalities, miniaturisation as well a...

Flexible MXene‐Based Composites for Wearable Devices

“…Generally speaking, stretchable strain sensors based on sophisticated slippage and crack propagation usually showed higher sensitivity compared with other piezoresistive mechanisms. [57] The overlapped area, crack configuration, length, width, density, cracked-area, and depth are the factors that affect the GF and working window. In addition to crack-assisted strain sensors, bioinspired interlocked microstructure geometries, whisker structures and micro/nanostructures could also be employed to improve GF.…”

A Wearable, Bending-Insensitive Respiration Sensor Using Highly Oriented Carbon Nanotube Film

“…Recent years have witnessed the explosive development of wearable sensors for monitoring human activities and healthcare services [1], [2]. Real-time health monitoring provides significant benefits for early-stage disease detection and costeffective treatment [3].…”

“…Real-time health monitoring provides significant benefits for early-stage disease detection and costeffective treatment [3]. The five traditional vital physiological indicators, generally considered essential to evaluate and monitor human health, are respiration rate, heart rate, body temperature, blood pressure and blood oxygen saturation [1]. Among these indicators, respiration rate provides a better evaluation to distinguish between stable and risky patients [1], [4]- [6].…”

“…The five traditional vital physiological indicators, generally considered essential to evaluate and monitor human health, are respiration rate, heart rate, body temperature, blood pressure and blood oxygen saturation [1]. Among these indicators, respiration rate provides a better evaluation to distinguish between stable and risky patients [1], [4]- [6]. Respiration rate is a critical sign in evaluating a person's health and detecting symptoms of respiratory diseases such as cardiac There are various approaches for respiration monitoring, which can be measured through either direct contact or noncontact methods [4], [7].…”

A Versatile Sacrificial Layer for Transfer Printing of Wide Bandgap Materials for Implantable and Stretchable Bioelectronics

“…Implantable and stretchable bioelectronics systems are of great interest for personal biomedical applications, owing to their lightweight, low stiffness, excellent adhesion to tissue surfaces, and high levels of mechanical flexibility. [1][2][3] A key feature of these devices lies in their capability for continuous monitoring of cellular and tissue activities in real-time, thus providing valuable information and actionable feedback for diagnosis and treatment of neurological disorders or cardiac diseases. [4][5][6][7][8] In this context, the integration of sensing materials with flexible polymeric substrates is of the topmost importance, as the basis for platforms that mechanically and geometrically match to soft, curved, and moving biological tissues.…”