Bastien Marchiori1 Roger Delattre1 Sylvain Blayac1 Marc Ramuz1

1, Ecole des Mines de Saint-Etienne, Gardanne, , France

We present a process which allows the patterning of fully stretchable organic sensors. The device consists of an active stretchable area connected with stretchable metallic interconnections. Such features allow the development of biosensors at the interface with the body; that can measure and address in real-time various physiological parameters at the interface with the body, but also with organs for in vivo experiments. This work is focused on sensors that will be fully stretchable, that is to say, all the materials are thought to be stretchable. The current research does not provide a completely simple and accurate process using the standard microelectronic techniques, allowing for the creation of such sensors.
In this work, we optimized the horseshoe shape of stretchable conductive interconnections encapsulated in polydimethylsiloxane (PDMS). An innovative patterning process based on the combination of laser ablation and thermal release tape ensures the fabrication of highly stretchable lines encapsulated in PDMS from conventional aluminum 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 on PDMS. Finally the formulation of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) is tuned to maximize its stretchability. The fabricated organic electrochemical transistor (OECT) shows state-of-the-art electrical performance with a high transconductance of 6.5 mS at no strain and a maximum stretchability of 38%, whilst maintaining a transconductance of up to 0.35 mS and channel current as high as 0.2 mA.