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

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 : 978-81-322-2256-9 DOI : 10.1007/978-81-322-2256-9_11 Any reuse of Material in this presentation or Paper should must be accompanied by appropriate citation

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

Block Diagram of Proposed System

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 18.28 mm in diameter is used to sense the bio signal

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

Smoothened Arterial Pulse Waveform Observed in Oscilloscope

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

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

Calculation of Stiffness & Reflectivity Index

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

Assessment of Pulse Wave Velocity

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

Variation of Stiffness Index and Pulse Wave Velocity obtained using the proposed method with age Our results :ΔSI/ Δ Age= 0.08805 ΔPWV/ Δ Age= 0.08430 Paper results :ΔSI/ Δ Age= 0.086 ΔPWV/ Δ Age= 0.080

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

Hardware, Software Integration & Real time monitoring