Phase 1. Wi-Fi system development for remote vital sign detection (Fig. 1)
Wireless signals captured by Wi-Fi routers can be used to monitor health information. The logic behind using Channel State Information (CSI) signals to detect breathing rate (BR) is based on processing the received signal.
A transmitter transmits a wireless signal which travels in the air and reaches the receiver, in what is called line-of-sight (LOS) propagation.
A non-line-of-sight (NLOS) propagation is when an obstacle exists anywhere in this straight line, the signal will be reflected, diffracted, and scattered. This is also known as multipath propagation.
The received signal from these scenarios will have different CSI data. The breathing of a person which causes the chest to move, will change the NLOS paths, and a sinusoid-like pattern in the CSI values can be the result of that.
In this work, the Nexmon tool captures the CSI to enable respiration detection. This additional frequency space and subcarriers improve accuracy.
An artificial neural network (ANN) was implemented. The ANN could define the BR of the respiration. The model was rapid and efficient with low error 4.7%. The same network can be generalized, e.g. to determine HR using a 0.75 to 2.5 Hz range. This ANN can identify abnormal characteristics, detect diseases and can be extended to issue health warnings, a step towards assisted living.
Phase 2. Radar System for remote vital sign detection (Fig. 2)
We built FMCW and CW radar prototypes. We observed that the distance between the radar and the person being monitored can affect the quality of the results due to the periodic null points problem.
To avoid this problem, an IQ demodulator was used along with an Arduino setup to collect the data. Signal quality was improved when we built the demodulator circuit using commercially available components such as mixers and couplers.
Furthermore, a non-contact low-cost radar-based system with automated DC components reduction was designed and implemented. That radar was capable of successfully detecting the breathing rate (BR) and heartbeat rate (HR) of a person.
Experimental results indicated very good accuracy. A Five Port Receiver (FPR) (alternative to a six-port receiver) was designed, simulated, fabricated, tested and integrated with the radar to further improve quality together with a novel concept. Results appear in Fig. 2.
This work has led to a patent (pending) and a possible spin-out SME:
https://visionrf.com(öffnet in neuem Fenster)Results allowed the ER and his team to participate in 3 entrepreneurial programmes: (i) Lean Launch, (ii) Venture Builder Incubator, (iii) Kickstart Converge Challenge, and win awards.
The work attracted News Media attention worldwide:
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https://www.heraldscotland.com/news/national-news/18936625.touch-free-vital-signs-monitoring-technique-revealed-scientists/(öffnet in neuem Fenster)-
https://www.insider.co.uk/news/scientists-seek-funding-touch-free-23147529(öffnet in neuem Fenster)-
https://eandt.theiet.org/content/articles/2020/12/touch-free-vital-signs-monitor-enabled-with-radar-system/(öffnet in neuem Fenster)-
https://uk.news.yahoo.com/touch-free-vital-signs-monitoring-000100531.html(öffnet in neuem Fenster)-
https://uk.finance.yahoo.com/news/touch-free-vital-signs-monitoring-000100531.html(öffnet in neuem Fenster)-
https://www.aol.co.uk/2020-12-10-touch-free-vital-signs-monitoring-technique-revealed-by-scientis.html(öffnet in neuem Fenster)Outreach activities include: Explorathon, Botanical Garden, as well as 1 book chapter and 3 conference presentations. Extended work lead to 1 book edited and 12 peer-reviewed journal articles.