Rutgers, the State University of New Jersey

Measurement Specialties, Incorporated

Stephen A Orbine

Steven P Petrucelli

Walter Welkowitz

Alan M Smith

Lisa K Liss

Damon Germanton

A circuit for measuring body impedance comprising a voltage source having a predetermined frequency and a current source; a first pair of electrodes adapted to receive one portion of the body for applying said current source to said body; a second pair of electrodes adapted to receive another portion of the body for sensing a voltage therebetween; a comparator having first and second inputs and an output for producing an output signal based on signals applied to said first and second inputs; an instrumentation amplifier arrangement coupled to one of said comparator inputs and responsive to the voltage across the second pair of electrodes for providing an input signal to said first comparator input; a variable resistor coupled to the second input of said comparator and responsive to said voltage source for developing a first voltage signal applied to said second comparator input; and a processor responsive to the output signal of the comparator for controlling the resistance of the variable resistor to cause a corresponding change in said first voltage, whereby when said voltage at said first input corresponds to the voltage at said second input of said comparator; said comparator output signal transitions from a first state to a second state to cause the processor to terminate resistor adjustment, whereby the body impedance value corresponds to the resistance value of the variable resistor.

Apparatus and method for measuring bioelectric impedance

The present weight scale performs automated self calibration by periodically initiating a measurement operation to determine the zero offset from a true weight reading due the weight scale's intrinsic weight. The weight scale's intrinsic weight will vary due to changes in environmental conditions such as temperature and humidity, which impact the behavior of the internal electronics that perform the weight measurement operations. The automated self calibration is provided by a counter circuit, clocked by a low power oscillator, that periodically initiates the weight scale's electronics to undertake a weight measurement of the tare weight value of the scale. The tare weight value is stored in memory until replaced by a subsequent tare weight value calculation. During a weight measurement operation the gross weight measurement is deducted by the tare weight value stored in memory to arrive at a net weight representing a user's true weight.

Apparatus and method for an automatic self-calibrating scale

Apparatus and methods for noninvasively measuring cardiovascular system parameters. According to a first preferred embodiment, the apparatus generates a time varying electrical voltage waveform having voltages corresponding to systolic and diastolic arterial pressures of the subject, the parameters being modelled by a lumped element electric circuit model analogous to the living subject's cardiovascular system, said circuit model including a systolic capacitor analogous to arterial compliance during systole, said apparatus comprising means for computing the value of said systolic capacitor from a measurement of an elapsed time between two voltage levels within a portion of said voltage waveform corresponding to systole, according to a predetermined criteria; and means for computing at least one said cardiovascular system parameter from said capacitor value. According to a second embodiment, a time-varying systolic arterial compliance is measured by measuring an arterial pulse pressure waveform. A third embodiment discloses a method of measuring cardiac output noninvasively from a cuff measurement of a patient's systolic minus diastolic blood pressure and a heart rate measurement. Cardiac output equations are derived from an unmodified Windkessel circuit model which models arterial compliance as a single lumped capacitance. General formulas for the value of the lumped capacitance are provided which are used to more accurately compute cardiac output from this circuit model.

Apparatus and methods for the noninvasive measurment of cardiovascular

Apparatus and methods for the noninvasive measurement of cardiovascular

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Bernardsville, NJ, United States of America

Stephen A Orbine