Stretchable artificial synaptic devices are promising for integration into soft neuromorphic systems. However, the organic electrochemical transistor (OECT)‐based synaptic device is challenging due to the difficulty of obtaining high mechanical deformability and durability as well as high long‐term plasticity (LTP) and retention time. Herein, a highly stable and stretchable synaptic OECT fabricated on a 3D mogul‐patterned substrate with stress absorption capability with improved synaptic properties is reported. The mechanical stability of a poly(3,4‐ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS) channel and, in turn, the OECT is improved by adding additives in the channel. Synaptic properties including synaptic weight (SW), LTP, and retention time could be tuned and improved by adopting a Nafion membrane between the channel and the gate electrode, which modifies the transport dynamics of ions in the electrolyte across the membrane. This approach paves a way for improving and tuning the synaptic properties of stretchable biomimetic OECT synapses.

The on-body immunodetection of biomarkers in sweat would significantly augment the potential of wearable body-interfaced biosensors for self-testing but has been limited due to the difficulty of integrating liquid handling and immunobiosensing devices in a wearable platform. Herein, a stretchable microfluidic immunobiosensor (SMIB) patch with hollow microfibers of elastomeric nanocomposites for the highly sensitive on-body biosensing of neuropeptide Y (NPY), a stress biomarker, in human sweat is reported. The SMIB patch is composed of a stretchable liquid handling device and an electrochemical impedimetric immunobiosensor made of hollow and conductive microfibers of reduced graphene oxide (rGO) and rGO-Ag nanowires in polyurethane matrix, respectively. The patch possesses a low limit of detection of 50 fm, a large dynamic range (50 fm-1 nm), good linearity, no labeling or reagent requirements, and facile formation in a patch form factor. By combining handling of the biofluid and delivery of the washing solution by a simple finger-touch operation as well as the analytical capability of NPY with an extremely low concentration in human sweat, the SMIB patch is a promising approach toward wearable non-invasive immunodetection for self-testing.

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Carbon nanofibers (CNFs) are the most basic structure of one-dimensional nanometer-scale sp2 carbon. The CNF’s structure provides fast current transfer and a large surface area and it is widely used as an energy storage material and as a sensor electrode material. Electrospinning is a well-known technology that enables the production of a large number of uniform nanofibers and it is the easiest way to mass-produce CNFs of a specific diameter. In this review article, we introduce an electrospinning method capable of manufacturing CNFs using a polymer precursor, thereafter, we present the technologies for manufacturing CNFs that have a porous and hollow structure by modifying existing electrospinning technology. This paper also discusses research on the applications of CNFs with various structures that have recently been developed for sensor electrode materials and energy storage materials.

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