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In recent years, wearable e-skin has emerged as a prominent technology with a wide range of applications in healthcare, health surveillance, human–machine interface, and virtual reality. Inspired by the properties of human skin, arrayed wearable e-skin is a novel technology that offers multifunctional sensing capabilities. It can detect and quantify various stimuli, mimicking the human somatosensory system, and record a wide range of physical and physiological parameters in real time. By combining flexible electronic device units with a data acquisition system, specific functional sensors can be distributed in targeted areas to achieve high sensitivity, resolution, adjustable sensing range, and large-area expandability. This review provides a comprehensive overview of recent advances in wearable e-skin technology, including its development status, types of applications, power supply methods, and prospects for future development. The emphasis of current research is on enhancing the sensitivity and stability of sensors, improving the comfort and reliability of wearable devices, and developing intelligent data processing and application algorithms. This review aims to serve as a scientific reference for the intelligent development of wearable e-skin technology. [ABSTRACT FROM AUTHOR]

Advances in stretchable and flexible sensors are responding to the emerging demand of wearable and portable smart electronics. A core component of these electronics are tactile sensing devices which detect external stimuli and obtain in-time information from the surroundings. A fusion of electronics, physics and materials science, tactile sensors have great potential in robots, biomedicine, flexible interactive devices, and several other applications. By integrating with a flexible polymer matrix conductive materials (nanometals, carbon nanomaterials, conducting polymers, etc.), which are either embedded in the matrix or surface-coated or sandwiched between films, the resulting conductive polymer-based composites are promising for flexible tactile sensors. This review summarizes recent advances across different types of tactile sensors, including piezoresistive, capacitive, piezoelectric, and triboelectric. Examples are highlighted on how the combination of new materials, unique structure designs, and novel fabrication methods can advance the progress of tactile sensors. Enhanced sensing performance and mechanical properties can be realized by integrating nanomaterials into polymer substrates. This review provides guidelines for further selection of polymer-based materials and design of tactile sensors. [ABSTRACT FROM AUTHOR]

To uncover the effects of preparation process on material properties represents an important advance in the translational application of composites in intelligent biomedicine. Here, we investigated how preparation temperature interferes with the biocompatible composite integrating piezoresistivity and mechanical flexibility. By thermomechanical blending, the composite from poly(ε-caprolactone) (PCL) and nanocarbon black (nanoCB) obtained electric conductivity, whilst single-axial drawing re-distributed the nanoCB in PCL matrix. The drawing at a temperature declined from 55 to 25 °C resulted in the elastic strain of PCL/nanoCB composite increasing from ~5 to ~30 % and elastic limitation increasing from ~15 to ~55 MPa. Meanwhile, the composite drawing at 25 °C demonstrated improved piezoresistive response (a sensitivity of ~16 at 10% strain) in sensing external loading. This work provides insights into how preparation temperature influences the composite structure and electromechanical properties. The method can be applied to engineer biocompatible electronics for intelligent biomedicine. [ABSTRACT FROM AUTHOR]

Flexible electronic skin has tactile perception similar to human skin, and has been widely used in the field of human-computer interaction. The flexible electronic skin is designed and fabricated using poly-vinylidene fluoride (PVDF), reduced graphene oxide (rGO), and room temperature vulcanised (RTV) silicone rubber. Performed tests reveal that RTV silicone rubber has good piezoelectric properties and can increase the output voltage of the electronic skin. The effect of the number and spacer thickness of PVDF/rGO films on the voltage are studied, and the optimal structure is determined accordingly. Obtained results show that the proposed electronic skin has a wider linear working range at low frequencies, the peak voltage reaches 8.80 V. Meanwhile, good flexibility and high sensitivity are obtained, which can realise the measurement of static and dynamic pressures. The proposed electronic skin is used to monitor and identify the muscle activity caused by pulse and breathing. [ABSTRACT FROM AUTHOR]

In this paper, a highly sensitive and transparent flexible temperature sensor fabricated from the polyethylene terephthalate flexible substrate and the nematic liquid crystal (1M0921900-000) is proposed, which simultaneously has low power consumption. Using the relaxation time (τ = RC) as an intrinsic variable to characterise temperature, a better linear fitting with temperature can be obtained at low voltage, high precision and more stable temperature monitoring can be achieved. The maximum sensitivity is −4.05%/°C at 0.1 V and 200 Hz. The transmittance of the sensor can reach 62.36–81.13% in the visible light range. Compared with the rigid liquid crystal temperature sensor, the rise time and the decay time of the sensor are reduced by 97.104% and 90.313%, respectively. In addition, it also has good stability, recovery, and durability, which shows potential applicability to electronic skin, prostheses, robots, and biomedical by accurately monitoring the change of external temperature. [ABSTRACT FROM AUTHOR]

Flexible electronics has huge potential to bring revolution in robotics and prosthetics as well as to bring about the next big evolution in electronics industry. In robotics and related applications, it is expected to revolutionise the way with which machines interact with humans, real-world objects and the environment. For example, the conformable electronic or tactile skin on robot’s body, enabled by advances in flexible electronics, will allow safe robotic interaction during physical contact of robot with various objects. Developing a conformable, bendable and stretchable electronic system requires distributing electronics over large non-planar surfaces and movable components. The current research focus in this direction is marked by the use of novel materials or by the smart engineering of the traditional materials to develop new sensors, electronics on substrates that can be wrapped around curved surfaces. Attempts are being made to achieve flexibility/stretchability in e-skin while retaining a reliable operation. This review provides insight into various materials that have been used in the development of flexible electronics primarily for e-skin applications. [ABSTRACT FROM PUBLISHER]