We describe a process allowing the patterning of fully stretchable organic electrochemical transistors (OECTs). The device consists of an active stretchable area connected with stretchable metallic interconnections. The current literature does not provide a complete, simple and accurate process using the standard thin film microelectronic techniques allowing the creation of such sensors. An innovative patterning process based on the combination of laser ablation and thermal release tape ensures the fabrication of highly stretchable metallic lines – encapsulated in polydimethylsiloxane – from conventional aluminium tape. State-of-the-art stretchability up to 70% combined with ultra-low mOhms resistance is demonstrated. We present a photolithographic process to pattern the organic active area onto stretchable substrate. Finally the formulation of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) is tuned to achieve an OECT with a maximum stretchability of 38% while maintaining transconductance up to 0.35 mS and channel current as high as 0.2 mA.

To become an integral part of the everyday outfits, wearable electronics are expected to be lightweight, conformable, imperceptible for the user and life‐proof. The prospect of integrating modern technologies in clothes requires electronic circuits in textiles which are able to perform complex computing with high reliability. Four approaches to smart textile fabrication are described in this review: textile circuits, functionalized fibers, flexible circuits, and hybrid stretchable circuits. In the first two, fabric serves as a substrate for the electronic circuit to maintain essential textile properties. In basic textile circuits, standard electronic components directly attached to fiber tracks insure elementary electronic functionalities while remaining a noninvasive solution. Then, functionalized fibers replace the rigid electronic parts, to make the electronics even more integrated, merging inside the core of the fiber. These most recent works are today limited to basic logic circuitry and quasi‐static applications. The third and fourth approaches have shown the advantages to rely on well‐established technologies with dedicated flexible/stretchable hybrid substrates processed separately from the garment. Despite a loss in wearing comfort, this axis of research is driven by the superior computational performances.

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In this paper, we demonstrate the first attempt of encapsulating a flexible micro battery into a contact lens to implement an eye-tracker. The paper discusses how to scale the battery to power various circuits embedded in the contact lens, such as ASIC, photodiodes, etc., as well as how to combine the battery with external harvested energy sources. The fabricated ring battery has a surface area of 0.75 cm2 yielding an areal capacity of 43 µAh·cm−2 at 20C. Based on simulated 0.35-µm CMOS ASIC power consumption, this value is large enough to allow powering the ASIC for 3 minutes. The functioning of the micro battery is demonstrated by powering an orange LED.

In this work, it is reported the fabrication of highly stretchable electrodes on a polydimethylsiloxane substrate. A laser ablation technique is used to design lithium nickel manganese oxide micropillars supported on serpentine Al interconnects. Morphological, mechanical, and chemical analyses have been investigated by scanning electron microscopy, optical microscopy, and energy dispersive X-Ray spectroscopy. We show that unlike compact and continuous electrode thin-films, vertical micropillar structures supported on Al serpentines can be stretched up to 70% without structural damage, which opens a new alternative for the fabrication and development of truly stretchable devices such as stretchable micro-batteries.