Patch-based physiological sensor
A body-worn patch sensor for simultaneously measuring a blood pressure (BP), pulse oximetry (SpO2), and other vital signs and hemodynamic parameters from a patient featuring a sensing portion having a flexible housing that is worn entirely on the patient's chest and encloses a battery, wireless transmitter, and all the sensor's sensing and electronic components. It measures electrocardiogram (ECG), impedance plethysmogram (IPG), photoplethysmogram (PPG), and phonocardiogram (PCG) waveforms, and collectively processes these to determine the vital signs and hemodynamic parameters. The sensor that measures PPG waveforms also includes a heating element to increase perfusion of tissue on the chest.
1 . A sensor for measuring a photoplethysmogram (PPG) waveform, a phonocardiogram (PCG) waveform, an impedance plethysmogram (IPG) waveform, and an electrocardiogram (ECG) waveform from a patient's chest, the sensor comprising:
a housing configured to be located on the patient's chest;
a reflective optical sensor for measuring the PPG waveform;
a digital microphone for measuring the PCG waveform;
a buzzer disposed in the housing, adjacent to the digital microphone, configured to generate an acoustic sound at a known amplitude and frequency;
a processor disposed within the housing; and
a set of electrodes that attach the optical sensor and the digital microphone to the patient's chest, with the set of electrodes connected to an ECG sensor configured to measure the ECG waveform,
wherein the set of electrodes is further attached to an IPG sensor, the IPG sensor configured to measure the IPG waveform,
wherein the IPG sensor is configured to inject current into the patient's chest, and further configured to measure the current to determine the IPG waveform,
wherein the digital microphone is configured to compare the acoustic sound generated by the buzzer with the PCG waveform to determine a quality of patient-sensor adhesion between the sensor and a surface of the patient's chest, and
wherein the processor uses time-domain analysis and frequency-domain analysis of the IPG waveform and uses time-domain analysis and frequency-domain analysis of the PCG waveform to collectively determine one of a coughing event, a wheezing event, and an apnea event by identifying amplitude modulation in the IPG waveform.
2 . The sensor of claim 1 , wherein the IPG sensor is configured to inject current at multiple frequencies into the patient's chest, and further configured to measure the current at multiple frequencies to determine the IPG waveform at multiple frequencies.
3 . The sensor of claim 1 , wherein the IPG sensor is configured to inject current at a single frequency into the patient's chest, and further configured to measure the current at the single frequency to determine the IPG waveform at the single frequency.
4 . The sensor of claim 1 , wherein the reflective optical sensor further includes a heating element.
5 . The sensor of claim 4 , wherein the heating element comprises a resistive heater.
6 . The sensor of claim 5 , wherein the resistive heater is a flexible film.
7 . The sensor of claim 1 , wherein the housing is of solid, unitary construction.
8 . The sensor of claim 1 , wherein the set of electrodes is a single electrode patch.
9 . A sensor for measuring a photoplethysmogram (PPG) waveform, a phonocardiogram (PCG) waveform, an impedance plethysmogram (IPG) waveform, and an electrocardiogram (ECG) waveform from a patient's chest, the sensor comprising:
a housing configured to be located on the patient's chest;
a reflective optical sensor for measuring the PPG waveform;
a digital microphone for measuring the PCG waveform;
a buzzer disposed in the housing, adjacent to the digital microphone, configured to generate an acoustic sound at a known amplitude and frequency;
a processor disposed within the housing; and
a set of electrodes that attach the optical sensor and the digital microphone to the patient's chest, with the set of electrodes connected to an ECG sensor configured to measure the ECG waveform,
wherein the set of electrodes is further attached to an IPG sensor, the IPG sensor configured to measure the IPG waveform,
wherein the digital microphone is configured to compare the acoustic sound generated by the buzzer with the PCG waveform to determine a quality of patient-sensor adhesion between the sensor and a surface of the patient's chest, and
wherein the processor uses time-domain analysis and frequency-domain analysis of the IPG waveform and uses time-domain analysis and frequency-domain analysis of the PCG waveform to collectively determine one of a coughing event, a wheezing event, and an apnea event by identifying amplitude modulation in the IPG waveform.
10 . The sensor of claim 9 , wherein the IPG waveform is one of time-domain bioimpedance waveform and a time-domain bioreactance waveform.
11 . The sensor of claim 9 , wherein the PCG waveform is a time-domain acoustic waveform.
12 . The sensor of claim 9 , wherein the IPG sensor is configured to inject current into the patient's chest, and further configured to measure the current to determine the IPG waveform.
13 . The sensor of claim 12 , wherein the IPG sensor is configured to inject current at multiple frequencies into the patient's chest, and further configured to measure the current at multiple frequencies to determine the IPG waveform at multiple frequencies.
14 . The sensor of claim 12 , wherein the IPG sensor is configured to inject current at a single frequency into the patient's chest, and further configured to measure the current at the single frequency to determine the IPG waveform at the single frequency.
15 . The sensor of claim 9 , wherein the reflective optical sensor further includes a heating element.
16 . The sensor of claim 15 , wherein the heating element comprises a resistive heater.
17 . The sensor of claim 16 , wherein the resistive heater is a flexible film.
18 . The sensor of claim 9 , wherein the housing is of solid, unitary construction.
19 . The sensor of claim 9 , wherein the set of electrodes is a single electrode patch.