An 87-mA Iontophoresis Controller IC With Dual-Mode Impedance Sensor for Patch-Type Transdermal Drug Delivery System Kiseok Song, Student Member , IEEE, Unsoo Ha , Student Member , IEEE, Jaehyuk Lee , Student Member , IEEE

Abstract

A bio-feedback iontophoresis controller IC is im- plemented into a fabric patch for transdermal drug delivery. An iontophoresis stimulator front-end (ISFE) can provide pro- grammable stimulation current in the range of 16–512- A amplitude, DC-500-Hz frequency, and 3% -100% duty cycle for controllable drug delivery. For safe and robust electrical stimulation, a failure detection circuit monitors the stimulation current to prevent overcurrent and stimulation voltage satura- tion. For bio-feedback operation, a dual-mode impedance sensor (DMIS) measures load and tissue impedances in the range of 5–50 k and 5 –1 k , respectively. In the DMIS, the gain of a programmable gain ampli fier and the injected current level of a chopper-modulated current source are automatically controlled to minimize power consumpti on. The proposed IC occupies 2.35 mm 2.35 mm including pads in a 0.11- m1 P 6 MC M O S technology and dissipates a pe ak power of 2.2 mW. The proposed IC is directly integrated on a 9 cm 4 cm fabric circuit board together with a 6.2-mAh coin battery for convenient iontophoresis treatment. The proposed sys tem provides a maximum dosage range of 87 mA , which is larger range than the 80-mA dosage range of a commercial iontophoresis patch. Using a re- configurable tetra-polar electrode con figuration, load and tissue impedances are measured during the iontophoresis treatment to provide bio-feedback. The proposed iontophoresis system is successfully veri fied by both in-vitro and in-v