## Blood pressure measurement system using NI myDAQ

Objection: using pressure sensor and NI myDAQ to measure blood pressure on PC.

Theory: When adding pressure to arm with band around, pulse will be cut off when pressure is too high. If the pressure is lower, the pulse becomes clear, then gently fades away. The point when pulse sound becomes clear is the diastolic blood pressure (DBP), and the point when pulse sound begins to fade away is the Systolic blood pressure(SBP). We amplify and analyze the pulse sound so that the blood pressure can be measured. With the help of LabVIEW and myDAQ, the signal can be digitized and further processed on PC.

Pictures showing the theory

Design

We used PT14 as pressure sensor, but the signal was quite low in voltage, so we used AD620 as amplifier before the signal was sent to myDAQ.

The pressure is converted to voltage then sent to myDAQ, and the pressure is in linear relation to voltage.

Circuit of sensor and amplifier

NI myDAQ

We used a blood pressure buzz as calibrator to adjust parameters. After calibration, the LabVIEW result was quite near to the calibrator.

 Actual blood  pressure(mmHG) Voltage(V) Calculated Blood pressure(mmHg) Deviation(mmHg) 116 2.52481 108.4226 7.577351 68 1.66045 72.5375 -4.5375 110 2.54984 109.4618 0.538194 62 1.53661 67.39611 -5.39611 112 2.36664 101.856 10.14401 70 1.58153 69.26103 0.738974 110 2.72951 116.9211 -6.92106 70 1.65596 72.35109 -2.35109 112 2.67176 114.5235 -2.52349 68 1.55233 68.04875 -0.04875 102 2.65123 113.6712 -11.6712 78 1.60559 70.25991 7.740089 110 2.5277 108.5426 1.457368 78 1.73457 75.6147 2.385299 110 2.39776 103.148 6.852014 62 1.5026 65.98413 -3.98413 fitting line y=kx+b k=41.51644 b=3.601536

blood pressure calibration

User interface in LabVIEW

Equipment

The LabVIEW file:

Reference:

• hokurikustr

• refrain

• 鑫鑫