Method for improving signal-to-noise in clinical spectrometric procedures

Abstract

A method of conducting clinical examination procedures by use of electrically actuated spectrometric apparatus, of the type which uses a sensor that is placed in contact with the patient to transmit and receive electromagnetic energy of selected wavelengths for non-invasive in vivo examination of a selected area on the body, in which a conductive member is placed in contact with the patient near or at the location of the sensor and connected to the signal-processing circuitry of the processor for the spectrometric signals in a manner such that the examination signals have significantly less noise content than would otherwise be true. In so doing, the signal-processing circuitry is isolated from the power supply circuitry, and the sensor and conductive member are preferably coupled to the processor by use of an isolation preamplifier, such that the signal-processing ground potential reference is maintained separate and distinct from the power supply ground. The specially-grounded conductive member that is placed in contact with the patient is preferably made part of the sensor itself, as by using a conductive material on at least part of the sensor surface that is placed in contact with the patient, and such a conductive surface element may comprise a flexible outer coating or layer of a compliant sensor which is conformable to the shape of the patient extremity to which it is applied. In this manner, the surface potential of the patient at the location of the sensor may be equalized with that of the signal-processing circuitry ground potential to substantially reduce signal noise content, and ambient sources of electrical noise may be effectively shielded as well.