Abstract
This paper reports on a systematic study of the flow sensitivity and resolution of micro-flow sensors intended for use in implantable ventricular-peritoneal shunts. The flow sensors utilize ferromagnetic flaps (transducers) whose deflection is detected by ultra-sensitive MTJ sensors (20mV/V/Oe). A working range of 0-40 ml/h was demonstrated at a maximum uncertainty of 4% RMS and a resolution of 0.4 ml/h. Earlier studies on this sensor unveiled significant low-frequency noise (drift) limiting the sensitivity to 1.4 ml/hr. The present study identifies thermal noise as the main source of low-frequency drift. Using thermal compensation it was found that the drift can be reduced below 2 ml per 24-hr. Combining an array of four transducers operating in series, it has been demonstrated that a sensitivity can be increased 10.9 fold. Furthermore, the report examines the long-term structural stability of the sensors and produces a corrosion report suggesting a lifespan of 15 to 55 years.
Original language | English (US) |
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Article number | 9052679 |
Pages (from-to) | 8455-8462 |
Number of pages | 8 |
Journal | IEEE Sensors Journal |
Volume | 20 |
Issue number | 15 |
DOIs | |
State | Published - Aug 1 2020 |
Keywords
- MEMS
- MTJ sensor
- VP shunt
- flow sensor
- thermal noise
ASJC Scopus subject areas
- Instrumentation
- Electrical and Electronic Engineering