The Research Of AC-Pulse Iontophoresis Apparatus

Iontophoresis apparatus is a non-invasive device used to enhance the delivery ofpermeation across human epidermal membrane or extract endogenous substancesfrom the body by applying a current across the membrane.At present, iontophoresis apparatus is a method that direct current power supply,or pulse electric current power supply. Because the electric current direction is alwaysconstant, the former will bring polarization effect across human epidermal membraneduring applying, not only affect the flux of medicine, but also be likely to results inthe burn to the human' s skin; although the latter resolves the problem of polarizationeffect, because of the characteristic of skin, the skin electrical conductance willproduce the variety in permeating transport, the pulse electric current then wouldchange along with skin electrical conductance, which will result in the variational fluxof medicine, which will make it impossible to control the flux of medicine exactly.This task adopt A.C.-pulse for iontophoresis (A.C. iontophresis). This apparatusovercomes the current apparatus ' s weakness. AC-pulse iontophersis apparatus notonly can avoid the skin' s polarization effect, but also can reduce the change of flux ofmedicine and the skin electrical conductance during the permeating transport. Theconstant conductance A.C. iontophoresis studies involved three points: (1) an initialapplied electroporation used to decrease the human skin electrical conductance to atarget level. (2) Utilize the one-chip computer to control the gain auto control circuit,make it produce a variable AC pulse, which can adjust by itself with the applyingcurrent to maintain the human skin electrical conductance at the target level during thetransport study, and (3)a low voltage D.C. offset applied simultaneously with the ACto assist permeating transport.This paper analyzes the transport theory of iontophoresis ,and completesthe whole frame design .Dual polarity power supply ,high–voltage pulse circuit system , the auto gain control system ,autonomous oscillation system andthe single chip microcomputer control and adjust system.The experiment completed the curve of the controlling component electric resistance and the voltage relation, the AC-pulse system output wave and the entire system circuit jobhas debuged. It is proved in the experiment that the skin resistance could keep constant due tothe adjusting of the A.C.volt acted on the skin. Because the working current and theflux of the medicine can be constant if the skin resistance is constant, so this apparatusprovide a new method for precise flux control therapy.