Skin pain resulting from mechanical compression is one of the most common pains in daily life and the indispensable information for electronic skin to perceive external signals. The external mechanical stimuli are transduced into impulses and transmitted via nerve fiber, and finally, the sensation is perceived via the procession of the nerve system. However, the mathematical mechanism for pain sensation due to mechanical stimuli remains unclear. In this paper, a mathematical model for skin pain sensation under compression is established, in which the Flament solution, the revised Hodgkin–Huxley model, and the mathematical model gate control theory are considered simultaneously. The proposed model includes three parts: a mechanical model of skin compression, a model of transduction, and a model of modulation and perception. It is demonstrated that the pain sensation degree increases with the compression amplitude and decreases with deeper nociceptor location in the skin. With the help of the proposed model, the quantitative relationship between compression pain sensation and external mechanical stimuli is revealed, which has a significant benefit in promoting the design and mechanism research of electronic skin with pain perception function.

As a representative of flexible electronics, epidermal electronic devices (EEDs) are extremely suitable for integration with biological tissues, such as human epidermis benefiting from the advantages of ultrathin, stretchability, and perfectly conformal attachment. Considering the low thermal conductivity of the EEDs polymer material, a large amount of undesired heat accumulation is prone to occur at the EEDs/skin interface, which brings challenges to the thermal management of the EEDs/skin system. The sharp temperature increment caused by ungratified heat dissipation will lead to thermal comfort issues, such as damage to biological tissues and also device failure, which will limit the application and promotion of EEDs to a large extent. A growing quantity of interesting and fruitful literature are addressing this conundrum. In this review, we comb and review the research of EEDs active thermal management, which mainly summarizes the strategies of heat flow regulation, phase change energy storage, and heating mode design. This review aims to provide the overall advances and reference source for future innovative research directions.

Controlling and tuning thermal conductivities of composites, including changing the direction of heat flux and thermal energy distribution, possesses significantly meaningful potential in many applications such as heat cloak, heat invisibility, heat protection and so on. In this paper, a novel design of composite metamaterial with periodic lattice structure, consisting of metal lattice layer (copper) and stretchable polymer matrix (Ecoflex), owns the ability to tune the anisotropic thermal conductivity through external strains. The parameters (such as geometric arrangement of metal lattice, loading strains), which can effectively influence the thermal properties of this metamaterial, have been investigated through finite element method considering large deformation. This new design may be helpful for designing and controlling heat flow and temperature distribution in the applications.

Epidermal electronic systems (EESs) are a representative achievement for utilizing the full advantages of ultra-thin, stretchable and conformal attachment of flexible electronics, and are extremely suitable for integration with human physiological systems, especially in medical hyperthermia. The stretchable heater with stable electrical characteristics and a uniform temperature field is an irreplaceable core component. The inorganic stretchable heater has the advantage of maintaining stable electrical characteristics under tensile deformation. However, the space between the patterned electrodes that provides tensile properties causes uneven distribution of the temperature field. Aiming at improving the temperature distribution uniformity of stretchable thermotherapy electrodes, an orthotropic heat transfer substrate for stretchable heaters is proposed in this paper. An analytical model for transient heat conduction of stretchable rectangular heaters based on orthotropic transfer characteristics is established, which is validated by finite element analysis (FEA). The homogenization effect of orthotropic heat transfer characteristics on temperature distribution and its evolutionary relationship with time are investigated based on this model. This study will provide beneficial help for the temperature distribution homogenization design of stretchable heaters and the exploration of its transient heat transfer mechanism.