Near‐Field Electrospinning Enabled Highly Sensitive and Anisotropic Strain Sensors

Abstract

The rapid advances in manufacturing technologies have provided great opportunities for scalable fabrication of novel sensing structures and devices. Here, the application of near‐field electrospinning to the fabrication of flexible strain sensors is explored. Through theoretical modeling, it is first verified that a strong anisotropic response of a strain sensor can be obtained through introducing a grid‐shaped design to its sensing layer. Following this guideline, near‐field electrospinning is applied to fabricate polyurethane grids with well‐controlled period and thickness and the grid is further decorated with conductive silver nanowires. Through tuning the structure of the polyurethane grid and the density of the silver nanowires, a high gauge factor (GF = 338.47) under high strain (200%) is achieved, representing the best sensing and stretching property combination reported for flexible strain sensors. In good agreement with the theoretical model, the strain sensors are only sensitive to the strain along the electrode direction and are insensitive to perpendicular direction strains. Based on this characteristic response, the excellent capability of the strain sensors in distinguishing hand movement and monitoring physiological signals is demonstrated, suggesting the great application potential of the sensors in robotic vision and prosthesis.

Materials, Electrical Performance, Mechanisms, Applications, and Manufacturing Approaches for Flexible Strain Sensors

“…In addition to PVDF, other electrospun polymers were also investigated for high performance strain sensor. For instance, anisotropic resistive-type flexible strain sensors based on PU have been developed by Zhao’s group by near-field electrospinning method [ 215 ]. Through the theoretical modeling and tuned geometry of the PU grid and concentration of the sprayed AgNWs, high GF value of 338.47 and high stretchability to 200% strain were resulted by the sensors.…”

“…( B ) Photographs of the sensor network fabricated by electrospinning process under 0%, 100%, and 200% strain. Reproduced with the permission from [ 215 ], copyright the Wiley Online Library, 2020. ( C ) Schematic illustration of the fabrication process of strain sensor by electrodeposition process.…”

Flexible Image Sensors with Semiconducting Nanowires for Biomimic Visual Applications

“…[70] The near-field electrospinning is an effective technique for the preparation of 1D inorganic semiconductor NWs, which opens an important application prospect for controllable deposition and precise operation of nano/ microwires. [98][99][100][101] Recently, Chen et al successfully printed pattern Zn 2 GeO 4 semiconductor microwire (SMW) arrays on rigid and flexible substrates using a self-made near-field direct printing system and fabricated high-performance UV photodetectors, as shown in Figure 4. [102] The near-field direct printing method has the ability to integrate large flexible electronic devices because of its high cost-effectivity, time-saving nature, and compatibility with any substrate.…”

Carbonized sunflower core based strain sensor for monitoring human motion

“…The fabricated sensors were able to distinguish the forces imposed on them, when they were applied on diverse objects in daily use. Zhao's group [6] utilized near-field electrospinning technology to prepare a kind of sensitive and anisotropic strain sensor, which achieved a high gauge factor (GF = 338.47) under high strain (200%). Long's team [7] fabricated polyaniline/polyurethane acrylate/Fe 3 O 4 (PANI/PUA/Fe 3 O 4 ) micro-ribbons through UV-assisted solvent-free electrospinning.…”