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Flexible sensors are the essential foundations of pressure sensing, microcomputer sensing systems, and wearable devices. The flexible tactile sensor can sense stimuli by converting external forces into electrical signals. The electrical signals are transmitted to a computer processing system for analysis, realizing real-time health monitoring and human motion detection. According to the working mechanism, tactile sensors are mainly divided into four types—piezoresistive, capacitive, piezoelectric, and triboelectric tactile sensors. Conventional silicon-based tactile sensors are often inadequate for flexible electronics due to their limited mechanical flexibility. In comparison, polymeric nanocomposites are flexible and stretchable, which makes them excellent candidates for flexible and wearable tactile sensors. Among the promising polymers, conjugated polymers (CPs), due to their unique chemical structures and electronic properties that contribute to their high electrical and mechanical conductivity, show great potential for flexible sensors and wearable devices. In this paper, we first introduce the parameters of pressure sensors. Then, we describe the operating principles of resistive, capacitive, piezoelectric, and triboelectric sensors, and review the pressure sensors based on conjugated polymer nanocomposites that were reported in recent years. After that, we introduce the performance characteristics of flexible sensors, regarding their applications in healthcare, human motion monitoring, electronic skin, wearable devices, and artificial intelligence. In addition, we summarize and compare the performances of conjugated polymer nanocomposite-based pressure sensors that were reported in recent years. Finally, we summarize the challenges and future directions of conjugated polymer nanocomposite-based sensors. [ABSTRACT FROM AUTHOR]

In this paper, we propose a set of novel tactile descriptors to enable robotic systems to extract robust tactile information during tactile object explorations, regardless of the number of the tactile sensors, sensing technologies, type of exploratory movements, and duration of the objects’ surface exploration. The performance and robustness of the tactile descriptors are verified by testing on four different sensing technologies (dynamic pressure sensors, accelerometers, capacitive sensors, and impedance electrode arrays) with two robotic platforms (one anthropomorphic hand and one humanoid), and with a large set of objects and materials. Using our proposed tactile descriptors, the Shadow Hand, which has multimodal robotic skin on its fingertips, successfully classified 120 materials (100% accuracy) and 30 in-hand objects (98% accuracy) with regular and irregular textural structure by executing human-like active exploratory movements on their surface. The robustness of the proposed descriptors was assessed further during the large object discrimination with a humanoid. With a large sensing area on its upper body, the humanoid classified 120 large objects with multiple weights and various textures while the objects slid between its sensitive hands, arms, and chest. The achieved 90% recognition rate shows that the proposed tactile descriptors provided robust tactile information from the large number of tactile signals for identifying large objects via their surface texture regardless of their weight. [ABSTRACT FROM AUTHOR]

Remarkable research efforts have been devoted to replicate the tactile sensitivity of human skin. Unfortunately, so far flexible pressure sensors reported barely fit the tactile requirements for fingertips, which could endure a pressure over 100 kPa and also can sense a gentle touch. It is vital to develop flexible pressure sensors which can ensure high sensitivity and wide operation range simultaneously, to satisfy the demands of mimicking the pressure sensing function of fingertips. In this work, a mini-size, light-weight but high-performance graphene film based pressure sensor is presented. Owing to the advanced structure with fluctuations on surface and fluffy-layered structure in cross-section of the graphene film, this pressure sensor shows an extraordinary performance of high sensitivity of 10.39 kPa-1 (0–2 kPa), ultra-wide operation range up to 200 kPa, impressively stable repeatability, high working frequency, rapid response and recovery time. Moreover, the demonstrated results of the detection of traditional Chinese medicine wrist-pulse waveform and the bionic fingertip tactile sensors, suggest the great application potential of the obtain device in biomedical field and bionic skins field. • Free-standing graphene film as active material of pressure sensors. • Widest operation range among flexible piezoresistive pressure sensors. • High sensitivity of 10.39 kPa-1 in 0–2 kPa. • Practicable applications for whist pulse detection and bionic fingertips. [ABSTRACT FROM AUTHOR]