Abstract
Recently, flexible tactile sensors based on three-dimensional (3D) porous conductive composites, endowed with high sensitivity, a wide sensing range, fast response, and the capability to detect low pressures, have aroused considerable attention. These sensors have been employed in different practical domain areas such as artificial skin, healthcare systems, and human–machine interaction. In this study, a facile, cost-efficient method is proposed for fabricating a highly sensitive piezoresistive tactile sensor based on a 3D porous dielectric layer. The proposed sensor is designed with a simple dip-coating homogeneous synergetic conductive network of carbon black (CB) and multi-walled carbon nanotube (MWCNTs) composite on polydimethysiloxane (PDMS) sponge skeletons. The unique combination of a 3D porous structure, with hybrid conductive networks of CB/MWCNTs displayed a superior elasticity, with outstanding electrical characterization under external compression. The piezoresistive tactile sensor exhibited a high sensitivity of (15 kPa−1), with a rapid response time (100 ms), the capability of detecting both large and small compressive strains, as well as excellent mechanical deformability and stability over 1000 cycles. Benefiting from a long-term stability, fast response, and low-detection limit, the piezoresistive sensor was successfully utilized in monitoring human physiological signals, including finger heart rate, pulses, knee bending, respiration, and finger grabbing motions during the process of picking up an object. Furthermore, a comprehensive performance of the sensor was carried out, and the sensor’s design fulfilled vital evaluation metrics, such as low-cost and simplicity in the fabrication process. Thus, 3D porous-based piezoresistive tactile sensors could rapidly promote the development of high-performance flexible sensors, and make them very attractive for an enormous range of potential applications in healthcare devices, wearable electronics, and intelligent robotic systems.
Highlights
StudyIn the recent years, advances in artificial intelligence and the internet of things have made it obvious that high performance flexible tactile sensors are a crucial sensing element, and they have become a research hotspot with growing demands in the electronic industry, with enormous practical applications, including personalized health-care monitoring systems [1,2,3,4], electronic skin [5,6,7], and human–machine interactions [8,9,10,11]
It can be clearly seen that the PDMS sponge obtains a smooth surface, with interconnected open-cells which construct an informal 3D porous structure
The well dispersed conductive nanocomposite carbon black (CB)/multiwalled carbon nanotube (MWCNT) solution homogeneously stacked through the inner cell walls of the 3D porous structure, and uniformly wrapped on the skeleton surface
Summary
Advances in artificial intelligence and the internet of things have made it obvious that high performance flexible tactile sensors are a crucial sensing element, and they have become a research hotspot with growing demands in the electronic industry, with enormous practical applications, including personalized health-care monitoring systems [1,2,3,4], electronic skin [5,6,7], and human–machine interactions [8,9,10,11]. In order to improve the sensitivity of piezoresistive tactile sensors, some research studies have been performed, and results from several works have demonstrated various fabrication strategies, rather than the conventional method of the micro-pyramid array structure [25,26] These include use of 3D printing [27], micro-pillar structure [17], chemical vapor deposition [28], sponge structure [20,29], and the dip-coating process [30,31]. A rapid response, ultra-wide detection range, and highly sensitive piezoresistive tactile sensor was integrated, based on a 3D porous dielectric layer, using a facile and cost-efficient strategy. Finger grabbing motion was demonstrated to illustrate its prospective applications in human–robotic interface
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