Flexible Pressure Sensors with a Wide Detection Range Based on Self-Assembled Polystyrene Microspheres

Abstract

Flexible pressure sensors are important components of electronic skin and flexible wearable devices. Most existing piezoresistive flexible pressure sensors have obtained high sensitivities, however, they have relatively small pressure detection ranges. Here, we report flexible pressure sensors with a wide detection range using polydimethylsiloxane (PDMS) as the substrate, carbon nanotube films as the electrode material, and self-assembled polystyrene microsphere film as the microstructure layer. The obtained pressure sensor had a sandwich structure, and had a wide pressure detection range (from 4 kPa to 270 kPa), a sensitivity of 2.49 kPa−1, and a response time of tens of milliseconds. Two hundred load–unload cycles indicated that the device had good stability. In addition, the sensor was obtained by large-area fabrication with a low power consumption. This pressure sensor is expected to be widely used in applications such as electronic skin and flexible wearable devices.

Flexible capacitive pressure sensors for wearable electronics

“…[1][2][3][4] Pressure sensors refer to electronic devices that can convert pressure to electrical signals, the research on which can be traced back to the early 1950s. 5 Flexible pressure sensors show superior properties compared with traditional stiff devices due to their flexibility, portability and wearable properties, [6][7][8] which can be nearly compatible with various complex object surfaces. Different sensing responses in various pressure ranges, including ultra-low pressure (o1 Pa), low pressure (1-10 kPa), medium pressure (10-100 kPa) and high pressure ranges (4100 kPa), endow them with broad application potential in physical-health (e.g.…”

Recent Progress in Flexible Microstructural Pressure Sensors toward Human–Machine Interaction and Healthcare Applications

“…Due to their excellent flexibility, transparency, and plasticity, polymers have been widely employed as the substrate materials of flexible sensors, and they also can be designed as a variety of microstructural sensors. Common polymers used for preparing flexible sensors include PDMS, [ 72 ] Ecoflex, [ 116 ] PET, [ 112 ] PI, [ 26 ] polystyrene (PS), [ 109 ] and PEDOT:PSS. [ 77 ] Because of the poor conductivity of these polymers, researchers usually coat conductive materials (e.g., carbon materials, Ag, etc.)…”

“…fabricated PS microspheres with different sizes, which were then integrated with carbon nanotubes for assembling piezoresistive microstructural sensors ( Figure a). [ 109 ] When applied pressure to these sensors, the upper and lower electrodes formed a closed path, while no pressure was applied, the microspheres separated the electrodes as a diaphragm. The pressure detection range of these sensors is 4–270 kPa, which is larger than most piezoresistive sensors.…”

“…Reproduced with permission. [ 109 ] Copyright 2019, MDPI. b) Schematic illustration of the formation process of the sensors by using PDMS films with microdome arrays.…”

Flexible Ecoflex®/Graphene Nanoplatelet Foams for Highly Sensitive Low-Pressure Sensors

“…However, conventional piezoresistive pressure sensors that are based on single-crystal silicon, metals, metal oxide, and nitride materials are not suitable for applications requiring soft, stretchable, and squeezable sensing devices due to their rigid and brittle nature. In contrast, new elastomeric nanocomposites that combine the properties of carbon nanotubes (CNTs) [5,6], Ag nanowires or nanoparticles [7], graphene [8], graphene oxide (GO) [9], or graphene nanoplatelets (GNPs) [10] with those of different polymers, such as polydimethylsiloxane (PDMS) [11,12], Ecoflex ® [13,14], rubber [15,16], or polyurethane (PU) [17], have recently shown high flexibility and excellent responsiveness to torsion, tension, and compression.…”