Cracking the code for self-repairing electronics with gelatine film
Researchers from the National Cheng Kung University, Taiwan, say the film could inhibit cracks in smart electronics and health-monitoring devices.
The researchers are reporting that cracks in the gelatine-glucose film disappear within three hours at room temperature and within 10 minutes when warmed to 60°C, once the simulated electronic device is bended.
A flexible film is sandwiched between conductive material to simulate an electronic device. ‘The glucose is added to the gelatine to increase the internal dynamic bonding,’ says Yu-Chi Chang, Assistant Professor at the University. The mixed solution is then spun on the cleaned indium tin oxide/polyethylene terephthalate substrates and baked at 80°C for 24 hours.
‘Glucose comprises an aldehyde group, which may react with a free amino group of an amino acid to create an imine. The reversibility of dynamic imine bonds gives rise to the dynamic behaviour of the polymeric networks, leading to repeatable self-healing behaviour.’
Chang continues, ‘After adding glucose, during the heating and self-healing process, the bonding of the C-C single bond becomes strong, which reduces the conductivity of the film and increases the resistance after healing. As a result, the resistance ratio of the memory device is higher than that of a newly manufactured device.
‘In addition to the self-healing ability of this…film, its performance in electronic components also subverts the general situation (cracks degrade electrical properties). From the computer-aided facility management analysis, we found that the filament is easy to form around the crack.’
The team suggests that the film can be extended to wearable devices, since such products are continuously flexed (cracked) during application. ‘Supplemented by the human body temperature (equivalent to heating effect), it is possible to extend it on wearable components. The service life of this type of component further reduces the generation of electronic waste,’ Chang shares.
‘The self-healing process was repeated three times, [and] the recovery condition remained the same after sequential cycles of bending and healing,’ explains Chang. ‘The resistive switching behaviour of the self-healing gelatine resistive random access memory was stable, and the average on/off ratio was over 105 during three cycles of testing, indicating that this recovery phenomenon was reproducible.’
The team is now applying the film to different electronic components – such as sensing components – for research and production. ‘In addition, the self-healing film is also used to complete the self-healing circuits without any complicated vacuum process (such as physical vapour deposition), and the results are expected to be published within the next year.’