08-16-2017, 09:09 PM
WEARABLE BIOSENSOR
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1. INTRODUCTION
Wearable sensors and systems have evolved to the point that they can be considered ready for clinical application. The use of wearable monitoring devices that allow continuous or intermittent monitoring of physiological signals is critical for the advancement of both the diagnosis as well as treatment of diseases.
Wearable systems are totally non-obtrusive devices that allow physicians to overcome the limitations of ambulatory technology and provide a response to the need for monitoring individuals over weeks or months.
2. DEVELOPMENT OF WEARABLE BIOSENSOR
2.1. RING SENSOR
It is a pulse oximetry sensor that allows one to continuously monitor heart rate and Oxygen saturation in a totally unobtrusive way. The device is shaped like a ring andthus it can be worn for long periods of time without any discomfort to the subject. The ring sensor is equipped with a low power transceiver that accomplishes bidirectional communication with a base station, and to upload data at any point of time.
2.1.1 BASIC PRINCIPLE OF RING SENSOR
With the amount Each time the heart muscle contracts, blood is ejected from the ventricles and a pulse of pressure is transmitted through the circulatory system. This pressure pulse when traveling through the vessels, causes vessel wall displacement which is measurable at various points .in order to detect palatial blood volume changes by photoelectric method, photo conductors are used. Normally photo resistors are used, for amplification purpose photo transistors are used.
LED Modulation
Power consumption problem can be solved with a lighting modulation technique.
Instead of lighting the skin continually the LED is turned on only for a short time, say
100-1000ns and the signal is sampled within the period. High frequency low duty
cycle modulation implemented minimizes LED power consumption.
Data Acquisition
It is used to collect the data from sensor and data are sampled and recorded.
Filtering
The signal from the PD-B as a noise reference a noise cancellation filter can be
built to eliminate the noise of PD-A that correlates with the noise reference signal
noise cancellation we use the adaptive noise filter.