Ultrafast Fabrication of Microneedle Array for Transdermal Ion Detection

More than 22,000 people were taken to hospital and nearly 100 people were killed due to heat waves across Japan in this summer. Hence, there is a high demand to detect the risk of heat stroke before it strikes. The minimally invasive insertion of needles offers considerable advantages over the conventional sensing routes. Moreover sensing at transdermal region is easily accessible without any complications. Measurement of electrolyte abnormalities resulting from prolonged sweating would be easiest way to detect the heatstroke risk. In this regard, we proposed a low cost, facile preparation, easy to use enzyme free sensor for the detection of ions in transdermal region. Microneedles was achieved by replicating structures from a laser engraved stainless steel master. And then PDMS elastomer was poured on stainless steel master, cured for 2 hours at 70°C and peeled off. The peeled off microneedle array structure is semi flexible and transparent. Then, Au/Ti electrodes were deposited on PDMS using shadow mask to make electrodes for sensing studies. Finally the electrodes were modified using Ag/AgCl and ZnO for sensing characterizations. Electrochemical studies were performed using the conventional three electrode system by employing electrochemical workstation (Bipotentiosrat 2325, ALS Japan). Cyclic voltammetric and amperometric techniques were used for electrochemical analysis of the bare and metal oxide functionalized microneedle electrodes in the range of 10-100 μM. To improve the selectivity of the sensor, the interference studies will be carried out using uric acid, glucose and dopamine. Finally, examination in in vitro animal studies is scheduled.