The tactile sensor lies at the heart of electronic skin and is of great importance in the development of flexible electronic devices. To date, it still remains a critical challenge to develop a large-scale capacitive tactile sensor with high sensitivity and controllable morphology in an economical way. Inspired by the interlocked microridges between the epidermis and dermis, herein, a highly sensitive capacitive tactile sensor by creating interlocked asymmetric-nanocones in poly(vinylidenefluorideco-trifluoroethylene) film is proposed. Particularly, a facile method based on cone-shaped nanoporous anodized aluminum oxide templates is proposed to cost-effectively fabricate the highly ordered nanocones in a controllable manner and on a large scale. Finite-element analysis reveals that under vertical forces, the strain/stress can be highly strengthened and localized at the contact apexes, resulting in an amplified variation of film permittivity and thickness. Benefiting from this, the developed tactile sensor presents several conspicuous features, including the maximum sensitivity (6.583 kPa −1 ) in the low pressure region (0-100 Pa), ultralow detection limit (≈3 Pa), rapid response/recovery time (48/36 ms), excellent stability and reproducibility (10 000 cycles). These salient merits enable the sensor to be successfully applied in a variety of applications including sign language gesture detection, spatial pressure mapping, Braille recognition, and physiological signal monitoring. Keywords anodized aluminum oxide, capacitive tactile sensors, electronic skin, highly morphology-controllable, interlocked asymmetric-nanocone arrays, P(VDF-TrFE)
Traditional electronic skin (e‐skin), due to the lack of human‐brain‐like thinking and judging capability, is powerless to accelerate the pace to the intelligent era. Herein, artificial intelligence (AI)‐motivated full‐skin bionic (FSB) e‐skin consisting of the structures of human vellus hair, epidermis–dermis–hypodermis, is proposed. Benefiting from the double interlocked layered microcone structure and supercapacitive iontronic effect, the FSB e‐skin exhibits ultrahigh sensitivity of 8053.1 kPa−1 (<1 kPa), linear sensitivity of 3103.5 kPa−1 (1–34 kPa), and fast response/recovery time of <5.6 ms. In addition, it can realize the evolution from tactile perception to advanced intelligent tactile cognition after being equipped with a “brain”. First, static/dynamic contactless tactile perception is achieved based on the triboelectric effect of the vellus hair bionics. Second, the supercapacitive iontronic effect based structural bionics of the epidermis–dermis–hypodermis and a five‐layer multilayer perception (MLP) enable the general intelligent tactile cognition of gesture cognition and robot interaction. Most importantly, by making full use of the FSB e‐skin with a six‐layer MLP neural network, an advanced intelligent material cognition system is developed for real‐time cognition of the object material species and locations via one contact, which surpasses the capability of humans.
Figure 1. Flexible tactile sensors based on the morphology controllable template methods and the morphology uncontrollable template methods and the potential applications in large tactile sensor array, intelligent robot gripper, and artificial tactile sensory memory. Image for "Lithography Template": Reproduced with permission.
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