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In recent years, with the rapid development of flexible electronic devices, researchers have a great interest in the research of electronic skin (e-skin). Traditional e-skin, which is made of rigid integrated circuit chips, not only limits the overall flexibility, but also consumes a lot of power and poses certain security risks to the human body. In this paper, a wireless passive e-skin is designed based on the surface acoustic wave sensor (SAWS) of lithium niobate piezoelectric film. The e-skin has the advantages of small size, high precision, low power consumption, and good flexibility. With the multi-sensing function of stress, temperature, and sweat ion concentration, etc., the newly designed e-skin is a sensor platform for a wide range of external stimuli, and the measurement results can be directly presented in frequency. In order to explore the characteristic parameters and various application scenarios of the SAWS, finite element analysis is carried out using the simulation software; the relationship between the SAWS and various influencing factors is explored, and the related performance curve is obtained. These simulation results provide important reference and experimental guidance for the design and preparation of SAW e-skin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Investigation of self-healing polymers for electronic-skin devices. • Overview of recent self-healing polymeric electronic skin advances. • Understanding of the thermodynamic contribution for self-healing fibrous network. • Conceptualization for electrospun self-healing breathable electronic skin. The development of wearable soft electronic skins requires the production of materials with high mechanical flexibility, an inherent self-healing mechanism, and high breathability. Autonomous self-healing mechanisms have been widely investigated to produce materials that can continue operating in hostile environments or after sustaining damage. However, mimicking the functions of natural human skin requires breathability. Given the thermodynamic considerations of the self-healing process and self-healing polymers, achieving porosity in such materials is a major challenge. Electronic skins fabricated through electrospinning have mechanical flexibility, breathability, and high overall performance; however, most electrospun self-healing fibrous materials have an extrinsic healing mechanism. Therefore, the further development of intrinsic healing methods is essential for the maturation of fibrous electronic skin technology. Several challenges must be addressed before the next generation of electronic skin devices can be developed. This review aims to discuss the shortcomings of current electronic skins and suggests several paths for developing fully self-healing and breathable electronic skins for future soft robotics and human–machine interfaces. [ABSTRACT FROM AUTHOR]

In this paper we present a new optical, flexible pressure sensor that can be applied as smart skin to a robot or to consumer electronic devices. We describe a mechano-optical transduction principle that can allow the encoding of information related to an externally applied mechanical stimulus, e.g., contact, pressure and shape of contact. The physical embodiment that we present in this work is an electronic skin consisting of eight infrared emitters and eight photo-detectors coupled together and embedded in a planar PDMS waveguide of 5.5 cm diameter. When a contact occurs on the sensing area, the optical signals reaching the peripheral detectors experience a loss because of the Frustrated Total Internal Reflection and deformation of the material. The light signal is converted to electrical signal through an electronic system and a reconstruction algorithm running on a computer reconstructs the pressure map. Pilot experiments are performed to validate the tactile sensing principle by applying external pressures up to 160 kPa. Moreover, the capabilities of the electronic skin to detect contact pressure at multiple subsequent positions, as well as its function on curved surfaces, are validated. A weight sensitivity of 0.193 gr-1 was recorded, thus making the electronic skin suitable to detect pressures in the order of few grams. [ABSTRACT FROM AUTHOR]

Self-powered flexible sensors play an increasingly important role in wearable and even implantable electronic devices. Silk protein is an ideal material for flexible sensors because of its terrific biocompatibility and controllable degradation rate. Here, we overcome the problem of mechanical flexibility and poor electrical conductivity of proteins, and develop a highly transparent, biocompatible, full-degradable and flexible triboelectric nanogenerator (Bio-TENG) for energy harvesting and wireless sensing. First, the mechanical flexibility of the silk protein film is greatly enhanced by the mesoscopic functionalization of regenerated silk fibroin (RSF) via adding glycerol and polyurethane (PU). Second, hollow silver nanofibers are constructed on the silk film to form an air-permeable, stretchable, biocompatible and degradable thin layer and utilized as friction electrode. The obtained Bio-TENG demonstrates high transparency (83% by one Ag gird layer), stretchability (Ɛ = 520%) and an instantaneous peak power density of 0.8 W m−2 that can drive wearable electronics. Besides, the Bio-TENG can work as artificial electronic skin for touch/pressure perception, and also for wirelessly controlling Internet of Things as a switch. • Conductive and ultrastretchable (520%) silk protein film was prepared. • Hollow silver nanofibers were constructed on silk film to enhance conductivity. • Bio-TENG was air permeable, biocompatible, stretchable and degradable. • Bio-TENG was applied for energy harvesting and wirelessly controlling Internet of Things. [ABSTRACT FROM AUTHOR]