1. Real time monitoring of Arterial Pulse Waveform Parameters using Low Cost, Non-invasive force transducer By
Aditya Sundar, Bits Pilani KK Birla Goa Campus
V. Harish, Madras Institute of Technology

2. Details of the Paper for this presentation
This Paper was presented at the International Conference on Advancements of Medical Electronics (ICAME 2015)
The Conference Proceedings were indexed in Lecture Notes in Bioengineering, Springer
ISBN :
DOI : / _11
Any reuse of Material in this presentation or Paper should must be accompanied by appropriate citation

3. Need for the method
Cardiovascular disease is currently the biggest single cause of mortality in the developed world
Stiffness Index and Pulse Wave Velocity have proven to be power predictors of risk of CVD
Pervious established measurement methods :
Invasive catheterization, Tonometry and Photoplethysmography
We propose a method using Simple, low cost & non-invasive Force Sensing Resistors

4. Block Diagram of Proposed System

5. Sensing technique
Force Sensing Resistors (FSR 402) is robust polymer thick film devices that exhibit a decrease in resistance with increase in force applied to the surface of the sensor
A standard Interlink Electronics FSR 402 sensor, a round sensor mm in diameter is used to sense the bio signal

6. Signal Conditioning & Conversion
Change in Resistance to Change in Voltage
Band Pass Filtering 1-5Hz & Notch Filtering at 50HZ

7. Smoothened Arterial Pulse Waveform Observed in Oscilloscope

8. Sampling, data acquisition & Digital Signal processing
NI-my DAQ used for acquisition
Set sampling rate at 100Hz
Digital Filtering in
LabVIEW at 1-5Hz
Data acquired every 5 secs
Parameter extraction
Performed using Mathscript
toolkit

9. Heart Rate calculation
Simple peak counting algorithm used to calculate the heart rate
Heart rate
= No. of peaks/5*60 (bpm)
Erroneous peaks should be ignored
Diagnosis of Tachycardia and bradycardia

10. Calculation of Stiffness & Reflectivity Index

11. Assessment of Pulse Wave Velocity
Two FSRs are placed 5 cm apart along the radial artery
Signals acquired simultaneously
Time difference between the pulses is calculated (ΔT)
Pulse Wave Velocity=
5cm/ ΔT

12. Assessment of Pulse Wave Velocity

13. Estimated value of Biological Parameters for test subjects using the proposed method
Gender
Age
Heart Rate (bpm)
Stiffness Index (SI) (m/s)
Reflectivity Index (RI)
Pulse Wave Velocity (PWV) (m/s) I
Male 21
74.2
5.93
0.47
7.41 II 22
68.3
6.22
0.53
7.50
III 45
80.5
7.97
0.38
9.32 IV 48
92.4
8.69
0.54
9.65 V 67
84.7
10.15
0.46
11.30 VI 65
71.8
9.83
0.56
11.43
VII
Female 42
76.6
8.32
0.72
9.28
VIII
83.1
8.54
0.45
9.36 IX 63
80.8
9.84
0.84
10.76 X 68
70.7
10.28
0.67
11.25

14. Variation of Stiffness Index and Pulse Wave Velocity obtained using the proposed method with age
Our results :ΔSI/ Δ Age=
ΔPWV/ Δ Age=
Paper results :ΔSI/ Δ Age= 0.086
ΔPWV/ Δ Age= 0.080

15. Photoplethysmography analysis
BIOLOGICAL PARAMETERS FROM DIFFERENT SENSORS
PARAMETER
FSR SENSOR
PPG SIGNAL
Heart Rate
78.3 BPM
Peak to Peak time
376 ms
364ms
Stiffness Index
8.57 m/s
8.85 m/s
Reflectivity Index
0.562
0.546

16. Hardware, Software Integration & Real time monitoring