wearable Ringbiosensor

WEARABLE RING

BIOSENSORPresented by :- MONALISA DEBATA 0701106032, 7th, I&E CET, BBSR

04/10/23 1Wearable Ringbiosensor,Monalisa Debata,7th, I&E

CONTENTS :-Wearable BiosensorConcept of ring biosensorDesign considerationsSensor ArrangementLight modulationTransmural pressureNoise referencePrototyping ApplicationsAdvantages & DisadvantagesConclusion


WEARABLE BIOSENSORWearable biomedical sensors and systems

could be defined as sensors/actuators and sensor-based communicative systems that can monitor and/or stimulate, and/or treat, and/or replace biophysical human functions .

Noninvasive in nature.They typically rely on wireless miniature

sensors enclosed in patches or bandages or in items that can be worn, such as ring or shirt.

Evaluation features: wearability, complexity, fault tolerance, aesthetic issues.


RING BIOSENSORIt is a pulse oximetry and photoplethysmographic

(PPG)sensor that allows one to continuously monitor heart rate and oxygen saturation in a totally unobtrusive way.

PRINCIPLES :-Blood pressure pulse causes vessel wall displacement.Detection pulsatile blood volume changes by

photoelectric method by photo resistorConnected as a part of voltage divider circuit and

produces a voltage that varies with the amount of blood in the finger.


Light absorption in various sections of finger04/10/23 5

Wearable Ringbiosensor,Monalisa Debata,7th, I&E

DESIGN CONSIDERATIONSSecure the LEDs and the photodetector (PD) at

a location along the finger skin such that the dc component may be influenced less by the finger motion.

Modulate the LEDs to attenuate the influence of ambient light as well as to reduce power consumption.

Measure the finger motion with another sensor or a second PD and use it as a noise reference for verifying the signal as well as for canceling the disturbance and noise.


SENSOR ARRANGEMENTLEDs and PD are placed on the flanks of the

finger rather than the dorsal and palmar sides.

Two possible location for placement of LED Transmittal illumination method Reflective illumination method

Differ significantly with respect to motion artifact, signal-to-noise ratio, and power requirements.


Average photon path for different arrangement

Corruption of PPG signal with applied motion


LIGHT MODULATIONDespite the superior stability and robustness,

transmittal PPG consumes more power.

Instead of lighting the skin continually, the LED is turned on only for a short time and the signal is sampled within this period.

The modulation of LED lighting provides an effective means for reducing ambient light disturbances. Reading the PD output while the LED is turned off yields the baseline PPG level attributed to the ambient light alone.


Comparison between slow and fast response time of PD


TRANSMURAL PRESSUREObjective is to increase the detected

amplitude of arterial pulsations (ac component ) so as to improve the signal-to-noise ratio of PPG.

Application of an external pressure will increase the pulsatile amplitude and reduce the transmural pressure.

Mechanism for holding the LED and PD must be designed such that it provides a safe level of continuous pressure, well below the established clinical threshold.


TRANSMURAL PRESSURE contd. PROBLEMS:

Largest PPG amplitude cuff pressure too high.

Cuff pressure order of 10mmHg.

SOLUTIONS:By providing a local,

noncircumferential increase in pressure near the sensor’s optical components that can avoid the potentially dangerous situation of long-term flow obstruction.


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Schematic of locally pressurized sensor band


NOISE REFERENCEFor reducing

motion artifacts and cancellation of noise.

PPG optical sensor as motion sensor

Reflective PPG arrangement.

Very low applied pressure.

Placement away from artery.


PROTOTYPINGComponents:• Optical sensor unit• PIC microcontroller• RF transmitter• Tiny cell battery• Use of double ring structure.Less distance between LED &

PD.Waveforms sampled at 100 Hz

transmitted to a PDA or a cellular phone carried by the patient.

PROTOTYPE-A


PROTOTYPING contd.PROTOTYPE-BHigh speed optical

deviceThe LED used is 6.7

times brighter than that of Prototype A.

Sensor band redesigned with the use of bio-compatible elastic materials for stable PPG.

Transmittal PPG signal does not collapse even when the hand is shaken.


PROTOTYPING contd.PROTOTYPE-C

Employs Local pressurization and motion detection methods.


APPLICATION


ADVANTAGES DISADVANTAGES

Continuous monitoring

Detection of transient phenomena

Promotes further diagnostic and therapeutic measures

Easy to useReducing

hospitalization fee

Initial cost is highLimited number of

physiological parameters to be monitored.


CONCLUSIONEffective and comfortableMobile information infrastructure that can be

made to the individual’s requirements to take advantage of the advancements in telemedicine and information processing.

It can play a vital role in realizing the future healthcare system.

It is anticipated that WBS will be leading to the realization of “Affordable Healthcare, Any place, Anytime, Anyone”.


REFERENCE H.Harry Asada, “mobile monitoring with

wearable ppg sensors”,IEEE engineering in medicine and biology magazine,vol 22, pp- 28-39 may/june 2003

Handbook of biomedical instrumentation ,Khandpur ,pp-138,233,238

http://www.wearables.gatech.eduhttp://www.google.co.in/images


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wearable Ringbiosensor