(C-110) Investigation of Different Pressure Transducer in In Vitro Pressure Acquisition

Introduction::

Mock circulatory loops have been widely used to investigate cardiovascular fluid mechanics.  In these loops, pressure measurements help analyze the functionality of individual sections of the cardiovascular system. Both the MLT0670 Disposable Blood Pressure Transducer (ADInstruments Inc. Colorado Springs, CO) and Pressure Transducer Sensor Pressure Gauge (Walfront Inc. Wuhan, CN) are commonly used to acquire data. Previous papers^[1] have used each of these pressure transducers individually, but few have compared the two to understand the benefits one may provide over another. Therefore, this study aims to compare the differences between the two transducers.

Materials and Methods::

This study focuses on the investigation with regard to the static pressure, which is exerted by various water heights in a stationary bucket. Both the MLT0670 Disposable BP Transducer and Pressure Transducer Sensor Pressure Gauge were connected to LabVIEW (National Instruments Corp Austin, TX) analysis software via appropriate wiring connections. In both setups, the electric signals were received by LabVIEW as an analog voltage. In the first setup, electric signals flowed from the MLT0670 Disposable BP Transducer through a load cell sensor amplifier (CGOLDENWAL Zhengzhou, CN) and a USB-6001 data acquisition board (National Instruments Corp Austin, TX). The amplifier’s signal output range was linearly related to the transducer’s operating pressure range during analysis. In the second setup, electric signals flowed from the Pressure Transducer Sensor Pressure Gauge to the USB-6001 Data Acquisition DAQ. During analysis, the transducers output voltage range was linearly related to its operating pressure range. The measurement from the two transducers were compared with theoretical pressure calculated by density of water and height from the water level where the transducers are placed.

Results, Conclusions, and Discussions::

Back calculating pressure from transducer-supplied voltage through a linear curve allows each transducers pressure measurement to be compared to a theoretical value based on density of water and height from the water level where the transducers are placed.

In vitro circulatory loops are meant to mimic the cardiovascular system, so sensors that detect 120mmHg at a minimum were chosen for this study. Each transducer was placed at water heights ranging from 0” to 6” in ½” intervals. Each water height compressed both transducers to specific degrees. The amount of compression each transducer experienced determined the magnitude of the electric signal sent out by the transducer. The MLT0670 Disposable BP Transducer detected pressures ranging from -50 to +300mmHg and the DAQ read the signal on a 0 to10V scale. MLT0670 Transducer pressure measurements were back calculated through the linear equation: pressure = 35*voltage-50mmHg. The Pressure Transducer Sensor Pressure Gauge sensed pressures on a 0 to10PSI scale and the DAQ read the signal from 0.5 to 4.5V. 0 to 10PSI Transducer pressure measurements were back calculated through the linear equation: pressure = 2.5*(voltage-0.5)*51.71mmHg/PSI. In this initial study, accuracy was defined as the degree to which each transducers pressure measurement conforms to the theoretical value at each ½” interval. The data collected in Table 1 and Fig 1 supports the conclusion that the MLT0670 Disposable BP Transducer is more accurate than the Pressure Transducer Sensor Pressure Gauge.

Acknowledgements (Optional): :
This work was conducted at UMass Lowell's REU Site: Inclusion and Innovation in Medical Devices, funded by the National Science Foundation (Award# 2243722).

References (Optional): :

[1] Peck, Laura. Pressure Acquisition System for In Vitro Mitral Valve Analysis, May 2018, scholarworks.uark.edu/cgi/viewcontent.cgi?article=1060&context=bmeguht&httpsredir=1.