A convenient, low-cost graphene UV-cured additive manufacturing electronic process to achieve flexible sensors

The reductions in manufacturing cost and process complexity of flexible sensors are of great significance in popularizing their applications. In present work, a Graphene UV-Cured Direct Electronic (GUDE) process based on photo-curing additive manufacturing technology is proposed and used to fabricate flexible electrode components of wearable respiratory sensors with excellent electrical responses. The method enables one to directly print the conductive structures without the need for cumbersome preparation and complex equipment. Compared with screen printing and microfabrication process that involve the mask preparation, the GUDE process can rapidly produce electrode patterns of any shape, thereby shortening the molding process and time cost of flexible electrodes. Moreover, GUDE process is additive manufacturing process, which saves the cost of raw materials. To verify the feasibility and application of the GUDE technology, a flexible humidity-sensing electronic device is fabricated. The humidity-sensing electronic device has a rapid response and recovery time of 0.27 s and 0.34 s, respectively, and a linear range in relative humidity variation between 39.3 % and 88.3 %. It can be perfectly attached to skin/surface where humidity needs to be monitored, and then be used in scenarios such as detection of body signals like respiration, disease diagnosis, monitoring of exercise status and industrial humidity/air flow, etc. In addition, excellent humidity responsiveness is attributed to enhanced adsorption capability of GUDE-printed surface microstructures due to large specific surface area and hydrophobic properties of graphene. In conclusion, the GUDE process, as a fast, direct electronic printing technology, offers broad prospects in the fabrication of flexible, high-performance electrical sensors, and has great potential for manufacturing advanced electronic devices.