Biodegradable and Highly Deformable Temperature Sensors for the Internet of Things

TLDR

Recent advances in biomaterials, thin‑film processing, and nanofabrication enable electronics with high mechanical stability and biodegradation, yet achieving reliable electrical performance while allowing large deformation and chemical degradation remains challenging. The sensors employ magnesium microstructures encapsulated in a compostable flexible polymer with a Young’s modulus of ~500 MPa, and packaging controls dissolution to a few days while enabling wireless Bluetooth connectivity with 200 mK resolution. The biodegradable temperature sensors exhibit a 10 ms response time and maintain resistance variation below 0.7 % under crumpling, folding, and stretching up to 10 %; arrays integrated onto a fluidic device enable smart flow mapping, and the system demonstrates wireless operation suitable for food tracking and post‑surgery monitoring.

Abstract

Recent advances in biomaterials, thin film processing, and nanofabrication offer the opportunity to design electronics with novel and unique capabilities, including high mechanical stability and biodegradation, which are relevant in medical implants, environmental sensors, and wearable and disposable devices. Combining reliable electrical performance with high mechanical deformation and chemical degradation remains still challenging. This work reports temperature sensors whose material composition enables full biodegradation while the layout and ultrathin format ensure a response time of 10 ms and stable operation demonstrated by a resistance variation of less than 0.7% when the devices are crumpled, folded, and stretched up to 10%. Magnesium microstructures are encapsulated by a compostable‐certified flexible polymer which exhibits small swelling rate and a Young's modulus of about 500 MPa which approximates that of muscles and cartilage. The extension of the design from a single sensor to an array and its integration onto a fluidic device, made of the same polymer, provides routes for a smart biodegradable system for flow mapping. Proper packaging of the sensors tunes the dissolution dynamics to a few days in water while the connection to a Bluetooth module demonstrates wireless operation with 200 mK resolution prospecting application in food tracking and in medical postsurgery monitoring.