GB1419660A - Electrical medical devices - Google Patents

Abstract

1419660 Electrical medical apparatus ESB INC 26 Jan 1973 [28 Jan 1972 19 Sept 1972 22 Dec 1972] 4154/73 Heading A5R An electrical medical device for modifying the naturally occuring electric potential of a zone of a living body has an electric signal generator producing a signal of cyclic waveform, each cycle of which has a rising and a falling portion and of which the rise and fall times differ by at least one order of magnitude and in which one of said portions has a frequency content within the range of from 10 Hz to 1 MHz, and coupling means in the form of electrodes or a coil connected to the generator and operative for reactively coupling said signal to said body zone. The generator may comprise a blocking oscillator including transistors 25, 26 and a feedback transformer 34 developing an asymmetrical sawtooth voltage across capacitor 28, this voltage being coupled via a d.c. blocking capacitor 43 to electrodes 50, 52, or via an operational amplifier (47), Fig. 2 (not shown), to one or more coils (50a), (52a). The rise time may be greater or less than the fall time which is chosen so that the falling waveform portions have little effect on the zone being treated. The frequency components of the effective rising portions are chosen in dependence on the zone treated: e.g. 10 Hz to 10 KHz for deep tissue, 10 KHz to 50 KHz for intermediate depths, 50 KHz to 200 KHz for subcutaneous tissue, 200 KHz to 1 MHz for cutaceous tissue. Electrode 52 may be about five times smaller than electrode 50, and the electrodes may be made of silver or a semiconductor, a dielectric material being placed between the electrodes and epithelical surfaces of the body. If coupling coil(s) are used they may be embedded in the treated zone. The generator with or without a power supply battery may be implantable and encapsulated in a body-compatible compound, and one of the electrodes 50, 52 may then take the form of a plate secured to the encapsulating casting, or each of the coils (50a), (52a) may be a wire wound bobbin secured to the casting. The electrodes or coils may be adapted to the form of a splint, cast or bandage around the treatment zone, or to a part of a splint, cast or bandage. The generator may be embedded in such a cast.