Irregular Microdome Structure‐Based Sensitive Pressure Sensor Using Internal Popping of Microspheres

Abstract

Modifying the surface morphology of an elastomer surface into 3D microstructures is crucial for various soft sensor applications. However, processes based on typical mold microfabrication and elastomer casting remain the dominant methodologies. This study demonstrates a novel strategy for generating 3D and irregular microdome structures for flexible pressure sensors through the internal popping of microspheres. When thermal treatment is applied to a composite film composed of microspheres and an elastomer matrix, the microspheres expand, and irregular microdome structures are generated. This composite film with an irregular microdome structure is utilized as a piezoresistive pressure-sensing film. The sensor shows high sensitivity (−50.45 kPa −1 ) owing to the heterogeneous contact change between the irregular microdome structure and a laser-induced graphene electrode; it also exhibits a short response time (τ 10-90% ≈ 39 ms), excellent repeatability, and high reliability. The sensor is applied in a fingertip-shaped pressure sensor to detect the blood pulse on the index finger and on electronic skin to recognize soft objects. Furthermore, a pressure sensor array that enables various functions such as drawing, multitouch, and deep learning-based motion control, is demonstrated.

Flexible Pressure Sensors with Combined Spraying and Self-Diffusion of Carbon Nanotubes

“…As summarized in Figure , most of the research on pressure sensors focus on obtaining high sensitivity under small pressure. ,,,− While some pressure sensors have not achieved high sensitivity and measurement range is relatively small, ,,, very few sensor studies have achieved ultrawide range measurement but did not achieve a high full-scale sensitivity. In this work, the SPC sensor employs a simple process to achieve ultrahigh sensitivity covering an ultrawide range and excellent durability.…”

“…The performance of the piezoresistive pressure sensor directly depends on the action mode of the microstructure of the active layer and the electromechanical properties of the materials used in the active layer. ,, On one hand, a variety of materials including carbon materials (carbon nanotubes, carbon black, graphene), − metal materials (gold nanowires, gold nanoparticles), , conductive polymers (PEDOT:PSS), , and compound materials (MoS 2 , MXene) ,− have been widely utilized as the active layers of sensors. MXene is prone to oxidative failure; its properties are not as stable as carbon nanotubes (CNTs), and the bonding force between metal materials and polymer matrix is difficult to control, which often results in a large change in the elasticity of the polymer matrix.…”

An ultra-thin flexible wearable sensor with multi-response capability prepared from ZIF-67 and conductive metal–organic framework composites for health signal monitoring

“…49 At the same time, unlike the mechanism of biological skin for sensing different degrees of pressure, most artificial pressure sensors rely on a single sensing mode and cannot sense external changes as multifunctional as skin, causing the sensitivity to rapidly decrease with increasing pressure, and the ability to cope with extreme pressures is very weak. [50][51][52] Mechanoluminescence (ML) is a nonthermal luminescence induced by mechanical stress applied to solids and was first discovered in 1605. 53,54 Doped ZnS phosphor can be prepared without pretreatment due to copper or manganese doping in the ZnS matrix, which can emit light under the action of external force.…”

A broad range and piezoresistive flexible pressure sensor based on carbon nanotube network dip-coated porous elastomer sponge

“…Basically, sensitivity, working range and stability of sensors depend on the micro/nanostructures that responded to external stimuli and the electromechanical signal conversion capability of constituent materials. 23,27,28 For example, micro/nanostructures like cracks, 29,30 wrinkles, 31,32 pyramids 33,34 and domes 35,36 could be popularly found in flexible pressure sensors which have a positive impact in realizing ultrahigh sensitivity. And sensing functional materials like MXene, Ag/Au/Cu nanowires, graphene are also frequently employed to develop pressure sensors with high sensitivity, 37–40 which are well known that they are much expensive.…”