A wearable self-aid microneedle chip based on actively transdermal delivery of epinephrine.

Epinephrine is important for first aid and usually applied via injection, which is painful and problematic in operation, thereby making it difficult to self-delivery. In this study, a method to actively transdermal delivery of epinephrine is proposed based on incorporating microneedles with iontophoresis, and then a wearable device is fabricated for rapid and controllable self-delivery of epinephrine. The device consists of a hydrogel microneedle array, a conductive drug delivery hydrogel, iontophoresis electrodes, and an encapsulated cartridge with a spring and self-locking micro-mechanism. The microneedles create subcutaneous microchannels, allowing the epinephrine contained in the hydrogel to enter the body under the control of iontophoretic currents. The dosage and rate can be adjusted at different levels by pressing the button so that it can be used by different groups of people for rapid self-aid and recovery from fatigue. The device can be worn in advance if required. In-vitro tests showed that the transdermal delivery rate of the device was between 0.02642 and 0.1059 mg/h cm². As a proof-of-concept application, in-vivo experiments showed that the device could reverse life-threatening shock reactions in a piglet model of hemorrhagic shock through the delivery of epinephrine.