Soft iontronic delivery devices based on an intrinsically stretchable ion selective membrane

Abstract Implantable electronically controlled drug delivery devices can provide precision therapeutic treatments by highly spatiotemporally controlled delivery. Iontronic delivery devices rely on the movement of ions rather than liquid, and can therefore achieve electronically controlled precision delivery in a compact setting without disturbing the microenvironment within the tissue with fluid flow. For maximum precision, the delivery device needs to be closely integrated into the tissue, which is challenging due to the mechanical mismatch between the soft tissue and the harder devices. Here we address this challenge by developing a soft and stretchable iontronic delivery device. By formulating an ink based on an in-house synthesized hyperbranched polyelectrolyte, water dispersed polyurethane, and a thickening agent, a viscous ink is developed for stencil patterning of soft ion exchange membranes (IEMs). We use this ink for developing soft and stretchable delivery devices, which are characterized both in the relaxed and stretched state. We find that their functionality is preserved up to 100% strain, with small variations in resistance due to the strain. Finally, we develop a skin patch to demonstrate the outstanding conformability of the developed device. The presented technology is attractive for future soft implantable delivery devices, and the stretchable IEMs may also find applications within wearable energy devices.