Abstract: An optical noninvasive vital sign monitor comprising a reflectance-type optical sensor within a pressurizable capsule retained by a headband, the capsule having an optically transparent or translucent inner wall adapted for placement against a subject's forehead. The optical sensor is mounted on the inside surface of the pressurizable capsule's inner wall, which contacts the subject's forehead during use, and includes a light source and a photodetector aimed toward the inside surface of the inner capsule wall. One embodiment of the vital sign monitor includes optical oscillometric circuit means responsive to an output signal from the optical sensor for determining systolic pressure, mean pressure and diastolic pressure during a transition in capsule pressure between a pressure greater than normal systolic pressure and a pressure less than normal diastolic pressure.

Abstract: A capacitive measuring pad is constructed of transverse conductive strips separated by a compressible insulator to form a matrix of pressure sensitive capacitive nodes. The nodes are repetitively scanned in sequence by a microcomputer to measure their respective capacitances, from which measurements a pressure map is then derived. The resulting pressure map may be displayed on a color graphics monitor with different colors representing diffrent pressures. Node capacitance is found by measuring the response of the mode to a driving signal of a known voltage. This measurement is accomplished by connecting one of the node's transverse conductive strips to the driving source and the node's other conductive strips to a sense amplifier. In order to isolate the node of interest from the influence of surrounding nodes, all of the conductive strips except the two intersecting the selected node are connected to ground.

Abstract: A pressure distribution measuring system includes a pad of insulating material disposed between two linear arrays of electrodes to form a matrix of capacitive nodes. A capacitance related output signal that is obtained from a node of interest is used as a feedback signal and applied to other capacitors that are connected in common with the node of interest. The feedback signal inhibits the flow of current through these commonly connected capacitors, and thereby isolates the measured signal from any changes in the capacitance of these other capacitors. The pad includes a cental array of linear electrodes sandwiched between two layers of dielectric foam material. Two outer, aligned linear electrode arrays, oriented perpendicular to the central array, are respectively disposed on the outside surfaces of the dielectric layers. In a preferred form, alternating electrodes in each outer array are located on opposite sides of a support substrate.