US-12616382-B2 - Wearable mechano-acoustic sensor

Abstract

A wearable mechano-acoustic sensor for continuous cardiorespiratory monitoring, and methods of making and using the same. The sensor includes a diaphragm with a chamber and a channel connected to the chamber, a plurality of electrodes including at least an anode and a cathode extending into the channel, and a liquid electrolyte solution that fills the chamber and channel. When the diaphragm is attached to a user's chest, mechano-acoustic movement from the chest cause the diaphragm to move, pushing the electrolyte solution across the electrodes. A voltage is applied to the anode and an electrochemical current is determined by the flux from the anode to the cathode by the modulation of the electrolyte solution across the electrodes and cardiorespiratory signals are measured from the electrochemical currents.

Inventors

• Yong Xu
• Zhiguo Zhao
• Xiaoce Feng
• Xiaoyu Chen

Assignees

• WAYNE STATE UNIVERSITY

Dates

Publication Date

20260505

Application Date

20230110

Claims (20)

1. 1 . A sensor for monitoring cardiorespiratory signals, comprising: a diaphragm defining a surface of each of a chamber and a channel connected to the chamber; a plurality of electrodes extending into the channel, the plurality of electrodes including at least a first anode and a first cathode; and a liquid electrolyte solution that fills the chamber and flows into the channel, surrounding the plurality of electrodes; wherein when a voltage is applied to the first anode, an electrochemical current is detectable as an ionic flux from the first anode to the first cathode when the liquid electrolyte solution modulates across the plurality of electrodes from mechano-acoustic movement of a chest.
2. 2 . The sensor of claim 1 , wherein at least one of: the chamber is circular and composed of a flexible rubber and the channel extends from a top of the chamber and is semi-circular in shape; the diaphragm is composed of a silicone rubber; and the chamber and the channel are disposed in a sensor body, and the diaphragm is attached to a top surface of the sensor body and covers the chamber and the channel.
3. 3 . The sensor of claim 1 , wherein the electrochemical currents are measurable to determine cardiorespiratory signals.
4. 4 . The sensor of claim 3 , further including a cavity; wherein the cavity is positioned at a terminal end of the channel, opposite the chamber, and the cavity is void of the liquid electrolyte such that it provides volume for the liquid electrolyte solution.
5. 5 . The sensor of claim 1 , wherein the plurality of electrodes includes a second cathode and a second anode.
6. 6 . The sensor of claim 5 , wherein the plurality of electrodes are platinum and are fabricated on a silicon wafer covered with silicone dioxide.
7. 7 . The sensor of claim 5 , wherein a distance of 10 μm is between each of the plurality of electrodes.
8. 8 . The sensor of claim 5 , wherein the plurality of electrodes are made on a flexible polyimide material.
9. 9 . The sensor of claim 1 , wherein the liquid electrolyte solution contains an iodide/triiodide redox couple.
10. 10 . The sensor of claim 1 , wherein the liquid electrolyte solution contains a redox couple with an opposite redox reaction at the first anode and the first cathode.
11. 11 . A method of manufacturing the sensor of claim 1 , comprising: building the chamber and the channel from a silicone rubber; spin-coating the diaphragm from the silicone rubber; attaching the chamber and the channel to the diaphragm; inserting the plurality of electrodes into the channel; filling the chamber with the liquid electrolyte solution; and sealing the chamber.
12. 12 . The method of claim 11 , wherein building the chamber includes forming a chamber mold via a 3D printer.
13. 13 . The method of claim 12 , wherein building the chamber includes pouring a silicone rubber mixture into the chamber mold, and curing the silicone rubber mixture.
14. 14 . The method of claim 13 , further including degassing the silicone rubber mixture prior to curing the silicone rubber mixture.
15. 15 . The method of claim 11 , wherein spin-coating the diaphragm includes rotating a silicone rubber film on an acrylic sheet.
16. 16 . A method of using a sensor to monitor cardiorespiratory signals, comprising: placing a sensor with a diaphragm on a chest of a user such that the diaphragm faces towards the chest, wherein the diaphragm defines a surface of each of a chamber and a channel connected to the chamber; applying a DC voltage to a plurality of electrodes extending into the channel; and detecting a mechano-acoustic signal by measuring two reversable electrochemical currents between the plurality of electrodes that are modulated by passing an electrolyte solution from the chamber to the channel as a result of mechano-acoustic movement of the chest.
17. 17 . The method of claim 16 , further including moving a diaphragm of the sensor; wherein movement of the diaphragm reflects mechano-acoustic movement of breathing and heartbeats of the user.
18. 18 . The method of claim 16 , further including measuring cardiorespiratory signals from the reversable electrochemical currents.
19. 19 . The method of claim 16 , wherein detecting the reversable electrochemical currents includes determining a triiodide flux from an anode to a cathode of the plurality of electrodes.
20. 20 . A system for monitoring cardiorespiratory signals, comprising: a diaphragm defining a surface of each of a chamber and a channel connected to the chamber, the diaphragm adapted to be attached to a chest of a user and flexible to move with the chest; a plurality of electrodes including an anode and a cathode, the plurality of electrodes extending into the channel; a liquid electrolyte solution filling the chamber and the channel, the liquid electrolyte solution able to flow across the plurality of electrodes as mechano-acoustic movement of the chest moves the diaphragm; a voltage source configured to apply a voltage to the anode such that a reversable electrochemical current is detectable as an ionic flux from the anode to the cathode when the liquid electrolyte solution modulates across the plurality of electrodes; and a controller for detecting the electrochemical currents and measuring cardiorespiratory signals from the electrochemical currents.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application 63/298,375, filed on Jan. 11, 2022, the contents of which is incorporated herein by reference in its entirety. TECHNICAL FIELD This disclosure relates generally to a wearable mechano-acoustic sensor for monitoring cardiorespiratory signals. BACKGROUND Heart and respiration activities offer physiological and pathological information through mechano-acoustic signals. Continuous monitoring of these signals may significantly improve the diagnosis and management of many cardiovascular and respiratory diseases. One example is heart failure (HF), which impacts over 37.7 million people globally. HF patients may have a very high rate of re-hospitalization, which may account for a large percentage of the total medical cost. It is envisioned that self-management of HF using wearable mechano-acoustic sensors may effectively decrease the re-hospitalization rate, improve the quality of life, and reduce mortality. In addition, common symptoms of respiratory disease and pneumonia like COVID-19 may include fever, cough, sore throat, and body aches, all of which may lead to shortness of breath. Abnormal heart and respiration signals may become a sign of infection for pre-clinical diagnosis. Symptoms in the early stage of infection may be subtle and asymptomatic. Therefore, wearable devices that are capable of accurate detection of subtle respiratory and cardiovascular variation, may be of great interest especially in the COVID-19 pandemic. Many wearable sensors have already been developed for recording heart or respiratory sounds continuously using custom-designed or off-the-shelf accelerometers. As the technology of flexible and stretchable electronics advances, wearable acoustic sensors based on polymer materials are known. However, there is a need for improved wearable sensors. Some more commonly available and used wearable devices offer limited information. For example, many wearable heart rate monitors utilize photoplethysmography, measuring heart rate by shining a green light through the skin, which may work better on lighter rather than darker skin. More accurate methods may be harder to track using a wearable device continuously. Thus, although the current methods of monitoring cardiorespiratory signals have been used to make diagnosis and treatment decisions, there is a need for having an ultra-high sensitive sensor for continuous cardiorespiratory monitoring. BRIEF DESCRIPTION According to the disclosure, a sensor for monitoring cardiorespiratory signals includes a diaphragm with a chamber and a channel connected to the chamber. The sensor includes a plurality of electrodes extending into the channel. The plurality of electrodes includes at least a first anode and a first cathode. The sensor includes a liquid electrolyte solution that fills the chamber and flows into the channel, surrounding the plurality of electrodes. When a voltage is applied to the first anode, an electrochemical current is detectable as an ionic flux from the first anode to the first cathode. The electrochemical current is varied or modulated when the liquid electrolyte solution moves across the plurality of electrodes from the mechano-acoustic movement from a chest. Also according to the disclosure, a method of using a sensor to monitor cardiorespiratory signals includes placing a sensor having a chamber and a channel on a chest of a user, applying a DC voltage to the plurality of electrodes, and detecting a mechano-acoustic signal by measuring two reversable electrochemical currents between the plurality of electrodes that are modulated by passing an electrolyte solution from the chamber across the plurality of electrodes as a result of mechano-acoustic movement of the chest. According to the disclosure, a method of manufacturing a sensor to monitor cardiorespiratory signals includes building a chamber from a silicone rubber, spin-coating a diaphragm from the silicone rubber, attaching the chamber to the diaphragm, inserting electrodes into the channel, filling the chamber with a liquid electrolyte solution; and sealing the chamber. Also according to the disclosure, a system for monitoring cardiorespiratory signals includes a diaphragm including a chamber and a channel connected to the chamber, the diaphragm attached to a chest of a user and flexible to move with the chest. The system includes a plurality of electrodes including an anode and a cathode, the plurality of electrodes extending into the channel. The system includes a liquid electrolyte solution filling the chamber and the channel, the liquid electrolyte solution able to flow across the plurality of electrodes as mechano-acoustic movement of the chest moves the diaphragm. The system includes a voltage source configured to apply a voltage to the anode such that a reversable electrochemical current is detectable as an ionic flux from the anode to the cathode when the liquid elect