Nano-toughening of transparent wearable sensors with high sensitivity and a wide linear sensing range

Abstract

Microcracking mechanism is an effective technique for creating highly sensitive piezoresistive strain sensors, but such sensors tend possess limited sensing range. Herein we present a new method of widening the...

Tuning Strain Sensor Performance via Programmed Thin-Film Crack Evolution

“…This results in Au films with distinctive microcrack morphologies and performances under strain. This mechanism in this work is different from the microcracked sensors structured on carbon composite/PDMS tuned by plasma treatment, , where the sensors need to be prestretched to a critical straining (100%) and microcracks were generated through stress transfer from exposed polymer substrates to the composite thin films. Our tuning results are analogous to adjusting the interaction force between the sensing metal and the elastomer by introducing another metal film as an adhesive layer prior to the deposition of a sensing metal film .…”

“…Strain sensors with high sensitivity can also be achieved by intentionally generating channel cracks on rigid metal films to design highly sensitive electronic skins. − Such cracked systems can only function in a strain range of less than 10%. Microcrack-based strain sensors with improved stretchability by replacing the metal film with composite materials have been reported. − However, most microcracked sensors structured on composite materials sacrifice their high sensitivity at a small strain range (<10%), which plays a critical role in capturing abundant signals of weak activities (such as wrist pulse, throat vibration, etc.). Therefore, the development of multifunctional strain sensors with highly tunable stretchability and sensitivity based on a simple material system and efficient approach is highly desired yet not reported.…”

Wearable Sensors for Remote Health Monitoring: Potential Applications for Early Diagnosis of Covid‐19

“…More recently, new classes of intrinsically stretchable sensing materials have been developed by creating conductive networks in highly stretchable polymers. [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ] Furthermore, self‐powered and low‐powered sensors have recently been created based on piezoelectric or triboelectric materials. [ 48 , 49 ] Below we summarize the state‐of‐the‐art wearable sensors capable of measuring respiratory behavior, body temperature, and blood oxygen saturation to the comparable performance as existing point‐of‐care diagnostic equipment, with a focus on material design and fabrication methods.…”

“…[ 86 ] The main mechanisms of piezoresistive sensors include geometric effects, the disconnection between overlapped nanomaterials, tunneling effects, or microcracking in the conductive thin films/coating. [ 37 , 43 , 45 , 86 ] A piezoresistive sensor is typically made by combining a conductive network formed by one or multiple electrically conductive materials (such as carbon‐based nanomaterials [ 46 ] including graphene, [ 47 ] carbon black, carbon nanotubes, and carbon nanofibers [ 44 ] ), as well as metal nanomaterials (such as copper, gold, and silver nanowires or nanoparticles [ 42 ] ) with an elastic polymer (such as silicone‐based elastomers and rubbers). For instance, polymer nanocomposites with electrically conductive networks, such as percolation network and segregation network, [ 90 ] and hydrogels [ 41 ] have been utilized in the design of flexible and stretchable sensors.…”

Rational Design of All Resistive Multifunctional Sensors with Stimulus Discriminability

“…gained major interests in recent years due to their promising applications in flexible electronics, [1][2][3] prosthesis development, [4][5][6][7] soft robotics [8][9][10] and healthcare devices. [11][12][13][14] To simultaneously monitor more than one type of physical stimuli, sensor networks consisting of multiple sensors should detect and decouple multiple sources of stimuli such as strain, pressure, and temperature without interference among them.…”