Flexible on-chip micro-supercapacitors: Efficient power units for wearable electronics

To meet the requirements of wearable and portable electronics, flexible and light-weight on-chip micro-supercapacitors (MSCs) have attracted tremendous attention due to the good mechanical and electrochemical performances as well as easy on-chip integration with flexible functional electronic devices. In this review, the recent progresses of flexible on-chip micro-supercapacitors are summarized. Typical strategies toward flexible onchip MSCs were first discussed, followed with the highlight of multifunctional on-chip MSCs including stretchable MSCs, self-healable MSCs, electrochromic MSCs and thermoreversible self-protection MSCs. Following these parts, wearable electronic systems integrated with flexible on-chip MSCs were discussed in detail. Finally, the challenges and future research emphasis on the flexible on-chip MSCs are put forward.