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to exhibit tissue-like mechanical properties-soft, stretchable, and conformable to biotissues; and also needs to be highly conductive to enable high-quality electrical communications. Traditional bioelectronics are made of rigid materials like metals, which exhibit high electrical conductivity but large mechanical mismatch with biotissues, resulting in nonconformable electrode-tissue interface, and severe inflammation. [3] Soft bioelectronics were developed in recent years to replace the rigid components in traditional bioelectronics with tissue-like soft materials to improve the conformability and reduce the adverse immune responses, [4,5] and this area asks for high-performance soft conductors to realize the functionalities of such tissue-like bioelectronics.Conducting polymer hydrogels are promising conductors that can serve as the electrodes for soft bioelectronics. [6,7] Hydrogels are water-rich networks that present high biocompatibility, tissuelike mechanical properties, and tunable functionalities desired for bioelectronics. [8,9] However, it is a great challenge for a conducting polymer hydrogel to achieve both high conductivity and large stretchability. [8,10] Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is the most promising conducting polymer. Pure PEDOT:PSS hydrogels have been reported to present a high conductivity on the level of ≈40 S cm −1 , [11,12] but they are brittle because the single PEDOT:PSS network cannot effectively dissipate strain energy. [13] Incorporating the conducting polymer with another polymer network-by in situ polymerization of EDOT in an existing ductile network, [14,15] or by forming a second network in an existing PEDOT:PSS network to construct an interpenetrating polymer network (IPN), [16] can enhance the stretchability of the hydrogel, but a huge decrease in electrical conductivity (<0.3 S cm −1 ) is observed. Such a compromise between stretchability and conductivity is potentially attributed to the deteriorated continuity and the low content of the conductive network when an electrically insulated network is introduced, [8] or the limited solubility of commercially available PEDOT:PSS solution (≈1 wt%).Herein, we report a double-network (DN) conducting polymer hydrogel of PEDOT:PSS and poly(vinyl alcohol) (PVA) with high electrical conductivity (≈10 S cm −1 ) and large stretchability Conducting polymer hydrogels are promising materials in soft bioelectronics because of their tissue-like mechanical properties and the capability of electrical interaction with tissues. However, it is challenging to balance electrical conductivity and mechanical stretchability: pure conducting polymer hydrogels are highly conductive, but they are brittle; while incorporating the conducting network with a soft network to form a double network can improve the stretchability, its electrical conductivity significantly decreases.Here, the problem is addressed by concentrating a poorly crosslinked precursor hydrogel with a high content ratio of the conducting polymer to achi...

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Hydrogels are a widely used ionic conductor in on-skin electronic and iontronic devices. However, hydrogels dehydrate in the open air and freeze at low temperatures, limiting their real applications when they are attached on skin or exposed to low temperatures. Polymer-ionic liquid gels can overcome these two obstacles, but synthetic ionic liquids are expensive and toxic. In this work, we present an ionic conductor based on polyacrylic acid (PAAc) and deep eutectic solvents (DESs) that well addresses the aforementioned challenges. We polymerize acrylic acid in DESs to get the PAAc–DES gel, which exhibits excellent stretchability (> 1000%), high electrical conductivity (1.26 mS cm−1), high adhesion to the skin (~ 100 N m−1), as well as good anti-drying and anti-freezing properties. We also demonstrate that the PAAc-DES gel can be used as an on-skin electrode to record the surface electromyographic signal with high signal quality, or as a transparent stretchable electrode in iontronic devices that can work at –20 °C. We believe that the PAAc–DES gels are an ideal candidate as epidermal electrodes or transparent stretchable electrodes.

BIA of the IVS is highly effective at creating a transmural ablation line, requiring less ablation and creating longer lesions than SUA. BIA ablation may have a role for post infarct VT involving the IVS.