Testing of pressure piezoelectric sensors
For Momo Medical
B.K.D. Koele (TU Delft - Electrical Engineering, Mathematics and Computer Science)
T.H.T. Leferink (TU Delft - Electrical Engineering, Mathematics and Computer Science)
T.L.P. Nguyen (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Jeroen Bastemeijer – Mentor
I.E. Lager – Graduation committee member
J Hoekstra – Graduation committee member
Menno Gravemaker – Graduation committee member
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Abstract
In this thesis, a test device is designed for the company Momo Medical. Momo Medical is developing a system that can be used to prevent pressure ulcers and adding more functionality is being investigated. For this system they need a device to test the functionality of the six piezoelectric sensors that are used in their product. The sensors’ response to a known pulse needs to be tested in order to give a pass/fail indication of the sensor quality. First, different ways of testing the sensors are investigated. Based on the results of the investigation, a final test setup is chosen and characterized. The test system developed in this thesis is based on a pneumatic setup, using a solenoid valve to control well-defined air pulses directed towards the sensors. Due to the addition of a reference load cell with custom designed read-out electronics, the device is able to test all six sensors one at the time and provides detailed feedback about the individual sensor quality. The test is performed using GUI-based software written in MATLAB, connected to a microcontroller. The software offers a broad variety of settings and can be configured according to Momo Medical’s wishes. After configuration, the test can be performed at the click of a button. The standard deviation of the device precision over three hours is sigma = 4.16, which equals a variation of cv = 0.82% of the mean μ = 504.8. This easily satisfies the requirements set byMomoMedical.