0 500 1000 1500 2000 250060

80

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180BP derived from Portapress

[mm

Hg]

sec

0 500 1000 1500 2000 25000.05

0.1

0.15

0.2

0.25PTT calculation with average

sec

sec

• Usually, the interval between the peak of the R-wave on the ECG and the onset of the corresponding pulse in the finger pad measured by PPG is defined as the PTT.• However, there is a considerable delay between the electrical cardiac activity (R-peak) and the mechanical ventricular ejection. This delay is referred to as the Pre-Ejection Period (PEP). The PEP is affected by pathologies, drugs and other factors, and therefore can cause impreciseness in the PTT measurement, and in the PTT-BP correlation.• Ballistocardiography (BCG) is the recording of the movements of the body caused by shifts in the center mass of blood in the arterial system and, to a lesser extent, of the heart, caused by cardiac contraction.

1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 15399

9.2

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9.8x 10

6 BP signal with max points identifying heartbeats

1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539-1

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1x 10

5 Chest signal with minmax points

sec

1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539-4

-2

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4x 10

4 Pelvis signal with minmax points

sec

241.2 241.4 241.6 241.8 242 242.2 242.4 242.6 242.8 243

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x 104

185 186 187 188 189 190 191 192 193 194 19550

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150Portapress BP signal- not filtered

sec

BP

[m

mH

g]

185 186 187 188 189 190 191 192 193 194 1958.35

8.36

8.37

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8.4x 10

6 Chest & Pelvis signals- not filtered

sec

1) Synchronized signals not filtered, received from the reference BP device Portapress (in the upper graph) and from EverOn sensors (in the lower graph) at rest. Chest signal in blue, Pelvic signal in green.

2) Proving that pelvic signal is comprised of: 1. signal generated in the heart and moved within the mattress to the pelvic sensor and most important 2. signal generated in the pelvic area of the body.

3) Final experiment

Real- time Detection of Blood Pressure changes

using contact free sensorsPresenting student: Efrat Herbst Instructed by: Zvika Shinar

To prove that signals are transmitted through the mattress and thus signal detected in each sensor is the superposition of the signal generated by the blood stream above the sensor with signal generated somewhere else and was Transmitted to the sensor through the mattress.Examining whether PTT can be measured using two EverOn sensors, placed under different locations of the body.

I. Median ratio between max/min peak to peak amplitude:

II. In preliminary calculations, PTT changes were found in the holding breath protocols: 55 [ms] relative to a 50 [mmHg] change in systolic BP and 70 [ms] relative to 60 [mmHg]:

Objectives

Introduction Methods Results

Discussion and ConclusionsI. Identifying the beat that arrives the pelvic area is critical. If we had

found that the signal received in the pelvic sensor is composed only by the chest signal transferred through the mattress, we had no point in continue this research. In our experiments we saw that signal generated by the pelvic area can be isolated and thus method is applicable.

II. As predicted, Change of PTT was found when BP changed. The relative is of 1.1 [ms] to 1[mmHg].

III. It seems that hand gripping for 5 minutes in order to change BP caused trembling of the hand, which makes it more difficult to find the heart beats and thus analyze the PTT.

IV. To the future, it is important to create a system that has the same clock sampler for all sensors, because of the importance of synchronized signals to the extent of a single heart beat.

Separated mattressesOne mattress

1st rest period1.25641.5629

2nd rest period1.44641.2446

3rd rest period1.5181.3667

Separated mattressesOne mattress

1st rest period1.60091.393

2nd rest period1.79991.3567

3rd rest period1.77681.3741