Fingerprint‐Inspired Flexible Tactile Sensor for Accurately Discerning Surface Texture

Abstract

Inspired by the epidermal-dermal and outer microstructures of the human fingerprint, a novel flexible sensor device is designed to improve haptic perception and surface texture recognition, which is consisted of single-walled carbon nanotubes, polyethylene, and polydimethylsiloxane with interlocked and outer micropyramid arrays. The sensor shows high pressure sensitivity (-3.26 kPa in the pressure range of 0-300 Pa), and it can detect the shear force changes induced by the dynamic interaction between the outer micropyramid structure on the sensor and the tested material surface, and the minimum dimension of the microstripe that can be discerned is as low as 15 µm × 15 µm (interval × width). To demonstrate the texture discrimination capability, the sensors are tested for accurately discerning various surface textures, such as the textures of different fabrics, Braille characters, the inverted pyramid patterns, which will have great potential in robot skins and haptic perception, etc.

High‐Performance Flexible Tactile Sensor Enabling Intelligent Haptic Perception for a Soft Prosthetic Hand

“…Recently, benefited from the development of material science and manufacturing, many flexible tactile sensors have been realized based on different transduction mechanisms including capacitance, piezoelectricity, resistance, and triboelectricity . To increase the sensitivity of the sensor, microstructure have been introduced in many researches, such as pyramid, hemispheres, and micropillar . These pressure sensors have been reported with excellent performance, but if used in the soft robotics, more or less issues still exists.…”

Highly sensitive capacitive pressure sensors for robotic applications based on carbon nanotubes and PDMS polymer nanocomposite

“…Reports on the use of PDMS as a dielectric in capacitive pressure sensors yield a sensitivity of 35.9 % N −1 in a small force range of 0-1 N (Ji et al, 2016). By incorporating metallic nanoparticles (Jain and Bhatia, 2016) like tungsten, iron, molybdenum and conductive nanowires (Wang, 2017) like the silver nanowire in PDMS, it demonstrates good pressure sensitivity compared to silicon-based pressure sensors and better pressure ranges up to 180 kPa. By means of soft lithography techniques, sensor dimensions of 15 µm (Cao et al, 2018) could be achieved.…”

“…By means of soft lithography techniques, sensor dimensions of 15 µm (Cao et al, 2018) could be achieved. Depending on the choice of nanofiller and measurement technique, the nanocomposite sensors work on either the piezo-resistive (Chen et al, 2017) or piezo-capacitive (Emon et al, 2017) principle. Carbonbased materials like pressure sensors are fabricated in different forms, such as sandwiched structure (Cui et al, 2016) or as arrays (Li et al, 2017) with fast response time < 200 ms. Pressure sensors based on graphite, CNT yarns, do not contain any polymer matrix and have advantages of being low cost, being biodegradable and having simple fabrication techniques, but they exhibit limitations with detectable pressure, either greater than 300 kPa in the case of graphite-based sensors or less than 60 kPa in the case of CNT yarns .…”

An ultra-sensitive and wide measuring range pressure sensor with paper-based CNT film/interdigitated structure

“…In particular, piezoresistive sensors, which can transform a variety of pressure signals into a variety of resistance signals, show key advantages, such as high accuracy, simple signal collection and economical manufacturing. In previous work [20][21][22], many researchers have focused on increasing pressure sensor sensitivity, rather than on increasing the pressure range of an individual sensor. In order to fully realize human body monitoring including pulse detection, voice recognition, wrist movement, and so on, the flexible pressure sensors need to possess not only a high sensitivity but also a wide pressure range [3][4][5], from a few Pa to tens of thousands of Pa [23][24][25].…”

“…Sensitive materials and structures are the two vital factors affecting the performance of pressure sensors. Generally, sensitive materials such as graphene [26][27][28], carbon nanotubes (CNTs) [20][21][22], metal nanoparticles [29,30], conductive nanowires [31][32][33], and organic polymers [34] are used in flexible sensors because they can be easily attached to the surfaces of flexible substrates or mixed into stretchable polymer. Among these materials, CNT has attracted a great deal of interest due to its remarkable electronic properties [35,36].…”