Development of an inlet pressure sensor for control in a left ventricular assist device

Bryan Fritz, Joshua Cysyk, Ray Newswanger, William Weiss, Gerson Rosenberg

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

A Tesla type continuous flow left ventricular assist device (VAD) has been designed by Penn State and Advanced Bionics, Inc. (ABI). When a continuous flow device is used, care must be taken to limit low pressures in the ventricle, which can produce an obstruction to the inlet cannula or trigger arrhythmias. Design of an inexpensive, semiconductor strain gauge inlet pressure sensor to detect suction has been completed. The research and design analysis included finite element modeling of the sensing region. Sensitivity, step-response, temperature dependence, and hysteresis tests have been performed on prototype units. All sensors were able to withstand the maximum expected strain of 82 μm/in at 500 mm Hg internal pressure. Average sensitivity was 0.52 ± 0.24 μV/mm Hg with 0.5 V excitation (n = 5 units). Step-response time for a 0- to 90-mm Hg step change averaged 22 msec. Hysteresis was measured by applying and holding 75 mm Hg internal pressure for 4 hours, followed by a zero pressure measurement, and ranged from -15 to 4.1 mm Hg (n = 3 units). Offset drift varied between 180 and -140 mm Hg over a 4-week period (n = 2 units). Span temperature sensitivity ranged from 18 to -21 μV/°C (n = 5 units). Gain temperature sensitivity ranged from -7.4 to 4.9 μV/°C (n = 5 units). With the inherent drift, it is currently not possible to use the transducer to measure actual pressures, but it can easily be used to measure pressure changes throughout the cardiac cycle. This signal can then be used in the control system to avoid ventricular suction events.

Original languageEnglish (US)
Pages (from-to)180-185
Number of pages6
JournalASAIO Journal
Volume56
Issue number3
DOIs
StatePublished - May 2010

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Bioengineering
  • Biomaterials
  • Biomedical Engineering

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