| 摘要 |
PCT No. PCT/SE91/00703 Sec. 371 Date Apr. 16, 1993 Sec. 102(e) Date Apr. 16, 1993 PCT Filed Oct. 18, 1991 PCT Pub. No. WO92/06634 PCT Pub. Date Apr. 30, 1992.A device and method for noninvasive depth-selective detection and characterization of surface phenomena in organic and biological material such as tissues by surface measurement of the electrical impedance of the material. The device includes a probe with a plurality of measuring electrodes separated by a control electrode. Measuring equipment measures impedance in a desired frequency range. An adjustable amplifier maintains a chosen control signal derived from the potential of one of the measuring electrodes at the control electrode without loading the measuring electrode. Depth selectivity is achieved by controlling the extension of the electric field in the vicinity of the measuring electrodes by the control electrode actively driven with the same frequency as the measuring electrodes. |
