Non-contact Vital Signs Sensor Research Articles

A Noncontact Vital Signs (NCVS) System for Potential Patient Monitoring Enabled by Robust Software Defined Radio (SDR)

This research proposes a robust non-contact vital signs (NCVS) sensor system for continuously monitoring the human respiration rate (RR) and heart rate (HR) within a distance of 1 to 2 meters. The novel Doppler-based NCVS sensor system is realized using an SDR (software defined radio) unit with optimized transmit/receive gain in commercial broadband, which filters intermediate frequency (IF) and operates at 2.4 GHz ISM band using a pair of small antennas. When compared with the vital signs data measured by traditional contact-based sensors, the NCVS sensing system demonstrates excellent accuracy in real-time RR/HR monitoring within 0.5/3 BPM (breath/beat per minute). We have obtained an IRB (Internal Review Board) approval to start a small clinical trial at Texas Tech University Health Sciences Center (TTUHSC) soon, hoping to use this system to effectively monitor vital signs of COVID-19 patients and to help telehealth delivery in the post-COVID-19 era.

Non-Contact Sensor for Long-Term Continuous Vital Signs Monitoring: A Review on Intelligent Phased-Array Doppler Sensor Design.

It has been the dream of many scientists and engineers to realize a non-contact remote sensing system that can perform continuous, accurate and long-term monitoring of human vital signs as we have seen in many Sci-Fi movies. Having an intelligible sensor system that can measure and record key vital signs (such as heart rates and respiration rates) remotely and continuously without touching the patients, for example, can be an invaluable tool for physicians who need to make rapid life-and-death decisions. Such a sensor system can also effectively help physicians and patients making better informed decisions when patients’ long-term vital signs data is available. Therefore, there has been a lot of research activities on developing a non-contact sensor system that can monitor a patient’s vital signs and quickly transmit the information to healthcare professionals. Doppler-based radio-frequency (RF) non-contact vital signs (NCVS) monitoring system are particularly attractive for long term vital signs monitoring because there are no wires, electrodes, wearable devices, nor any contact-based sensors involved so the subjects may not be even aware of the ubiquitous monitoring. In this paper, we will provide a brief review on some latest development on NCVS sensors and compare them against a few novel and intelligent phased-array Doppler-based RF NCVS biosensors we have built in our labs. Some of our NCVS sensor tests were performed within a clutter-free anechoic chamber to mitigate the environmental clutters, while most tests were conducted within the typical Herman-Miller type office cubicle setting to mimic a more practical monitoring environment. Additionally, we will show the measurement data to demonstrate the feasibility of long-term NCVS monitoring. The measured data strongly suggests that our latest phased array NCVS system should be able to perform long-term vital signs monitoring intelligently and robustly, especially for situations where the subject is sleeping without hectic movements nearby.

Overnight non-contact continuous vital signs monitoring using an intelligent automatic beam-steering Doppler sensor at 2.4 GHz.

Doppler-based non-contact vital signs (NCVS) sensors can monitor heart rates, respiration rates, and motions of patients without physically touching them. We have developed a novel single-board Doppler-based phased-array antenna NCVS biosensor system that can perform robust overnight continuous NCVS monitoring with intelligent automatic subject tracking and optimal beam steering algorithms. Our NCVS sensor achieved overnight continuous vital signs monitoring with an impressive heart-rate monitoring accuracy of over 94% (i.e., within ±5 Beats-Per-Minute vs. a reference sensor), analyzed from over 400,000 data points collected during each overnight monitoring period of ~ 6 hours at a distance of 1.75 meters. The data suggests our intelligent phased-array NCVS sensor can be very attractive for continuous monitoring of low-acuity patients.

A Review on the Design of Non-Contact Vital Signs (NCVS) Biosensors for Long-Term Continuous Monitoring

It has been the dream of many scientists and engineers to realize a non-contact remote biosensing system that can perform continuous, accurate, and long-term monitoring of human vital signs as what we saw in some SciFi movies. Having a system that can measure and record key vital signs (such as heart rates and respiration rates) remotely and continuously without touching the patients, for example, can be an invaluable tool for physicians who need to make rapid life-and-death decisions. Such a system would also be an effective tool to help physicians and patients make better informed decisions when viewing a patient’s long-term monitored data. Therefore, there has been a large increase in research activities to develop a system that can monitor a patient’s vital signs and quickly transmit the information to healthcare professionals. Radio-Frequency (RF) Non-contact vital signs (NCVS) monitoring system are particularly attractive for long term vital signs monitoring because there are no wires, electrodes, wearable devices, nor contact-based sensors for the subjects to worry about. Approach: In this paper, we will provide a brief review on some latest development on NCVS sensors, and also compare them against a novel phased-array Doppler-based RF non-contact NCVS biosensor system we have built in our RF-SoC Lab. To determine the accuracy of our NCVS sensor, the heart rate measurements from our NCVS system are compared against an external contact-based piezoelectric finger sensor as a reference. Objective: In some of our previous works, the NCVS sensor performance was tested within a clutter-free anechoic chamber inside our Lab to mitigate the environmental clutters. To examine the performance of our NCVS sensor in a more practical setting, most tests here were performed within the typical Herman-Miller type office cubicle setting, inside a section of our Lab. Additionally, we will detail the measurement data to demonstrate the feasibility of long-term noncontact vital signs monitoring. Conclusion: The measured data strongly suggests that our latest phased array NCVS system should be able to perform long-term vital signs monitoring, especially for situations where the subject is sleeping and there is not expected to have hectic movements nearby. Recommendation: Our phased-array NCVS biosensor system appears to be quite robust and attractive. We will be performing several 24-hours tests to quantitatively analyze the effects of the background noise to long-term vital signs monitoring in office cubicle setting, and report our findings on these important topics in the near future. In the future, we also plan to continue to perform long-term NCVS monitoring on subjects during their sleep next for potential applications on sleep apnea and sudden cardiac arrest (SCA) patients.