The healthcare industry forecasts that patients’ health in future will be monitored by wearable sensors that would be wirelessly networked. Now manufacturing such devices could become easier with a novel process developed by King Abdullah University Of Science and Technology (KAUST) which enables printing of high-performance silicon-based computers on attachable sticker-like surfaces.
Fitting wearable electronics on the asymmetric contours of the human body requires a shift from traditional computer development. By printing circuits on polymers or cellulose using liquid ink made from conductive molecules is one approach that offers quick assembly of devices and low packaging costs. However, this results in rigid modules that create uncomfortable hotspots and increased weight because the approach requires conventional silicon components to handle applications such as analog-to-digital conversion of signals.
In order to overcome this obstacle, research by Muhammad Hussain and his team from KAUST Computer, Electrical and Mathematical Science and Engineering Division for the past four years focused on various ways to increase flexibility of silicon materials while retaining their performance.
“We are trying to integrate all device components—sensors, data management electronics, battery, antenna—into a completely compliant system,” explained Hussain. “However, packaging these discrete modules on to soft substrates is extremely difficult.”
While investigating potential electronic skin applications, researchers developed a sensor with narrow aluminum foil strips that changed conductivity at different bending states.
The devices feature high-mobility zinc oxide nano-transistors on silicon wafers which were thinned down lithographically to micro-scale dimensions for maximum flexibility. Using 3-D printing techniques, the team encapsulated the silicon chips and foils into a polymer film backed by an adhesive layer.
By employing inkjet printing for conductive wiring patterns on various surfaces such as paper or clothing, the researchers managed to devise a method to ensure e-sticker sensors worked in multiple applications. Custom-printed decals were then attached or re-adhered to each location.
According to Galo Torres Sevilla, first author of the findings and a KAUST Ph.D. graduate, “You can place a pressure-sensing decal on a tire to monitor it while driving and then peel it off and place it on your mattress to learn your sleeping patterns.”
Hussain added that with the robust performance and high-throughput manufacturing potential of the decal electronics, numerous innovative sensor deployments could be potentially launched. “I believe that electronics have to be democratized—simple to learn and easy to implement. Electronic decals are a right step in that direction,” he said.
More information can be found at: King Abdullah University Of Science and Technology.