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Flexible electrodes applied to different positions of the human body to detect bioelectrical signals need to be conductive with respect to both the skin and the external circuit. However, electrodes fabricated with micromachining can only be made conductive on one side, which requires inserting connection wires, thus affecting skin adhesion and leading to a more fragile circuit on the soft substrate. This paper proposes an e-interface designed with an innovative folding transfer process, which can fold nanometer thick electrodes in a macroscopic way. Avoiding the difficulties of fabricating double layer as well as an insulation layer, the e-interface is not only skin-conformable for long-term wear but also provides a stable connecting pad for the subsequent circuit by its double-sided conductivity. The e-interface can be stretched to more than 25% of its original length and achieve electrical stability in the long-term signal acquisition. A responsive ECG signal is obtained by the e-interface, and the signal remains stable during exercise.

of amalgamating rigid elements and nonstretchable components on a soft substrate, strain isolation is proposed as a promising strategy in order to fabricate stretchable devices by incorporating island-bridge structure for these stretchable electronics. [13,14] The original strain isolation is offered by the modulus contrast between rigid components and the soft substrate, but constricted by the materials participating and the thickness of each part, leading to delaminating at the interface created by the components and the substrate. Furthermore, enhanced strain isolation schemes exploit geometrically structured substrates, [15] elastomeric substrates with stiff platforms, [2,16] soft elastomers with liquid-filled cavities, [2,17] and polymer substrates with programmable rigidity. [18] However, these approaches make the fabrication arduous, prompting further problems. Utilizing geometrically structured substrates not only elevates the thickness of the entire device but the substrates need to be pre-strained as well, making the subsequent transfer printing process a taxing affair. Although stiff platforms embedded into elastomeric substrates can fortify brittle components, there is still an adequate chance of occurrence of delamination at the interface of stiff platforms and soft substrates. Liquid filled in cavities of soft elastomers is prone to leakage or evaporation. Considering the scheme of polymer substrate with programmable rigidity, aqueous solution oxidized substrate offers low spatial resolution despite adopting airlaid paper to absorb liquid and confine the oxidized regions. In addition, manual operations are involved in the process, thus curtailing the success rate as well as the efficiency of manufacturing. Hence, these scenarios demand a new method of lamination between rigid components and soft substrates to be developed, which could not only safeguard the brittle parts but also employ a novel process to streamline the preparation.The field of soft electronics boasts microfabrication as its conventional manufacturing method; but in order to create soft electronic devices, it must interweave other approaches with it, like transfer printing. [19,20] To balance the perplexities brought about by this top-down process, the other approach proposed is a bottom-up process, which is to print the corresponding materials with the technique of assembling the rigid components and soft substrate in a single procedure. [21] Several printing methods (e.g., inkjet printing, [22][23][24] electrohydrodynamic printing, [25][26][27] aerosol printing, [28,29] direct ink writing (DIW), [30,31] etc.) have been introduced to fabricate such soft The trend of incorporating soft electronic systems in current electronics framework is fast becoming a wide phenomenon in healthcare as they provide a more suitable human-machine interface making it conveniently possible to achieve real-time, continuous health monitoring and therapy. However, the effective integration of an entire system with the soft and dynamic human skin has prov...

In article number 1900614, Ran Liu and co‐workers propose a flexible electronic device composed of different modulus materials stretched on human skin, during which its contour of wave line indicates its non‐uniform deformation. In the heterogenous rigidity assemblies, the rigid components can be easily assembled on the flexible substrate to achieve the combination of rigidity and flexibility of the flexible electronics.