Hydrogel Cryo-Microtomy Continuously Making Soft Electronic Devices

Standard fabrication of soft electronic devices with both high controllability and yield is highly desirable but remains a challenge due to the modulus mismatch of component materials through a one-step process. Here, by mimicking the freeze-section process of multicomponent biological tissues containing low-modulus muscles and high-modulus bones, for the first time, a hydrogel cryo-microtomy method to continuously making soft electronic devices based on a sol-solid-gel transition mechanism is presented. Polyvinyl alcohol (PVA) electrolyte and aligned nitrogen-doped multi-walled carbon nanotube (N-MWCNT) array electrode are demonstrated as low- and high-modulus components to fabricate soft supercapacitors with high performances. Stable interfaces form between frozen PVA electrolyte and N-MWCNT electrodes with matched moduli at subzero temperature and are well maintained during cryo-microtomy process. The resulting soft supercapacitors realize controllable patterns, tunable thicknesses from 0.5 to 600 μm, high yields such as 20 devices per minute even at lab scale, and high reproducibility with over 75% devices in 15% performance fluctuation. This cryo-microtomy method is further generalized to fabricate other soft devices such as sensors with high sensing properties.