Analysis of a GMR-based plethysmograph transducer and its utility for real-time Blood Pressure measurement.

The paper presents study and analysis of a Giant Magneto Resistance (GMR)-based magneto plethysmograph and illustrates its efficacy as a tool for real-time cuff-less measurement of Blood Pressure (BP). The proposed scheme employs two GMR sensors and associated biasing and signal conditioning in its architecture. The delay between output of the GMR sensors is used to estimate the BP. The methodology, circuits and signal processing stages used are described in the paper. A prototype of the GMR-sensing solution is developed and tested. Initially, tests are carried out to determine the quality and characteristics of the plethysmographs produced by developed sensor unit, in different conditions such as various body positions, bias current etc. Good quality bio-signals were obtained during the above tests. Then, the experiments were conducted on 29 volunteers to find the feasibility of developed scheme as a BP monitor. The results obtained show that the performance of developed BP monitor is within acceptable limits.

Feasibility Study of a Giant Magneto-Resistance Based Respiration Rate Monitor.

This paper reports a simple and reliable electronic technique for the estimation of respiration rate (RR). Giant Magneto-Resistance (GMR) based sensors are employed to extract a plethysmograph signal from the subject. This signal is filtered and processed further through simple signal processing stages to obtain RR indication. The feasibility of the system has been studied on a prototype built and associated experimentation on 20 volunteers. The developed system provided clean plethysmographic signals, whose relevant features are shown to possess a relation with RR. Test results shows that the worst-case error in RR estimation of the system is merely 2 breaths per minute. Further, the capability of the system for detecting breathing cessations is studied and results reported. The system can be extended to function as a heart-rate (HR) monitor. Some basic results which proves the working and accuracy of system as a HR estimator is also given in the paper. The proposed system can be used for effective estimation of the above two vital signs in clinics, automotives, wearable devices, etc.

Non-invasive heart rate monitoring system using giant magneto resistance sensor.

A simple heart rate (HR) monitoring system designed and developed using the Giant Magneto-Resistance (GMR) sensor is presented in this paper. The GMR sensor is placed on the wrist of the human and it provides the magneto-plethysmographic signal. This signal is processed by the simple analog and digital instrumentation stages to render the heart rate indication. A prototype of the system has been built and test results on 26 volunteers have been reported. The error in HR estimation of the system is merely 1 beat per minute. The performance of the system when layer of cloth is present between the sensor and the human body is investigated. The capability of the system as a HR variability estimator has also been established through experimentation. The proposed technique can be used as an efficient alternative to conventional HR monitors and is well suited for remote and continuous monitoring of HR.