Constructing Microstructured Starch Films via Hydrogen Bonding Manipulation for Transient Flexible Electronics.

Transient flexible electronics have attracted increasing attention recently due to their degradability in the nature being free of electronic waste. However, how to balance the degradability and high performance remains a huge challenge. A mass-producible, multifunctional, and transient flexible device was developed in this work based on starch films with knoll-like microstructures by manipulating hydrogen bonds between the starch molecules that verified through molecular dynamics simulation. The optimized hydrogen bonding makes the starch film soft and tough, benefiting the stability of the microstructure under deformations, thereby improving device performance. The obtained sensor can detect strain with gauge factor of 550.8; it can detect pressure with a sensitivity of 0.401 kPa-1 in the range of 0-210 kPa. As a sensor enables reliable human motion and facial expressions, it can also be used as a triboelectric nanogenerator with an output voltage of 28.5 V, demonstrating its capability for energy harvesting and self-powered sensing. Furthermore, the starch-based device can be recycled and reused. The degradation tests indicate that the device exhibits physically transient behavior. Notably, integrated with a probabilistic neural network, the sensor achieves 98.33% accuracy in lip-reading recognition, highlighting its potential in human-machine interaction. The starch-based device also demonstrates controllable on-demand transient behavior, enabling secure, time-limited operation for information protection applications.