A high-sensitivity sensor for cardiorespiratory examination may be consumed continuously by cardiac patients or others who require regular examination.
The small and inexpensive sensor, named in Applied Physics Letters, by AIP Publishing, is based on an electrochemical system containing two ionic types of iodine, I– and me3–. A solution in which these electrolyte products are placed in a small round intestine surrounded by a thin flexible diaphragm, allows subtle movements to be detected when applied to a patient’s chest.
Small movements resulting from the heartbeat and breathing cause the flexible diaphragm to move the I.–/ I.3– solution enters a narrow channel in the device, where it is detected electronically by four platinum electrodes.
The sensing body was made using Ecoflex 00-20, which has been proven to be a very soft, strong, and stretchy silicone rubber that is widely used in medical imaging, orthotics, and prosthetics. . “
Yong Xu, Author
The researchers created a mold for the circular chamber and the associated narrow channel using 3D printing. A solution to form Ecoflex 00-20 was poured into the module to form the body of the sensor and was also coated with spinning on a rapidly rotating disc to produce the thin diaphragm. After connecting the diaphragm and the chamber body together, the examiners used a syringe to fill the chamber with the electrolyte solution.
The resulting device is only 28 millimeters wide and is safe for the skin, so it can be attached directly to the patient’s body. The device was able to detect a heartbeat with high sensitivity. A signal-to-sound ratio greater than 6: 1 was achieved, which is considered good.
Relief can be found with this tool in two different ways. Due to the lightness of the sensor, it deforms when the chest contracts and expands at the time of breathing, acting as a strain sensor. The other way the sensor detects relief is due to the way the size of the breast cavity changes during breathing, altering the heartbeat signal. In this way, relief is found indirectly through changes in heart rate.
The authors suggest that their sensor could be used to detect respiratory diseases, such as COVID-19, which often leads to shortness of breath.
“The symptoms at an early stage of the disease may be subtle,” Xu said. “Consumables that are able to detect scarce respiratory and cardiovascular differentiation are of great interest especially during the routine pandemic.”
Source:
American Institute of Physics (AIP)
Magazine Reference:
Zhao, Z., et al. (2021) Accessible mechanical-acoustic sensor based on redox electrochemical response for continuous cardiorespiratory examination. Applied Physics Letters. doi.org/10.1063/5.0029108.