Session: 15-01-01: ASME International Undergraduate Research and Design Exposition

Paper Number: 100702

100702 - Novavent Project Sensor Development 

 

 

An introduction that provides the motivation and purpose of the research:

During the initial phases of the COVID-19 pandemic, the NovaVENT project was initiated to address the shortage of ventilators. In the present phase, of which this study is a part, the continuing development of the ventilator pivoted towards developing a rugged, field deployable ventilator for use in developing countries and in harsh environments.  

 

As part of the NovaVENT ventilator, a sensor package must be designed and integrated into the inspiratory and expiratory flow lines, with the objectives of measuring and providing feedback on (1.) CO2 concentration in the expiratory flow, (2.) O2 concentration in the inspiratory flow, and (3.) instantaneous inspiratory and expiratory volumetric flow rate. A further objective is to integrate the sensors into a compact electronic package. After assembly and testing of the prototype, CO2 wasn’t detected fast enough to produce an accurate Capnogram, a plot of CO2 Concentration (PPM) vs Time (s). The final prototype developed in the previous phase of this work required a small air pump to increase the flow rate of the air across the sensor to obtain an adequate response. As such, the purpose of the work was to determine if flow to the sensor could be reconfigured so that it can be made to impinge normal to the sensor’s active surface to reduce the CO2 sensor response time and eliminate the air pump.

 

The contribution of the work toward advancing science and/or engineering: 

This work advances scientific knowledge of how these CO2 Sensors work, and can be implemented into an engineering system, such as a ventilator. Within Fluids Systems, Biomedical and Controls Engineering, CO2-Microcontroller serial/digital communication and CO2 sensor response are explored extensively.

 

The methodology used (e.g., experimental techniques, analytical, computational, etc.):

Beginning with a hypothesis that impinging flow, normal to the CO2 sensor will enhance the rise time of the CO2 Sensor, three alternative CO2 sensor housing designs were 3D-printed, each implementing this hypothesis in different ways. Experimental testing was conducted with both controlled CO2 gas and regular human breath. For controlled CO2 gas testing, 5000PPM gas was used in line with a regulator valve, CO2 sensor, and a ball valve, to simulate a 5-second step impulse at a controlled flow rate. For regular breath testing, a sharp, a one-second breath was taken to best approximate a step impulse. This data was repeated using a 6V DC air pump in line. 4mm Tygon tubing was used to deliver the test CO2 gas to the sensor. Experimental data was recorded using GASLAB software and an Arduino Microcontroller. 

 

Results and Conclusions:

1. Four different housing designs were tested using two methods: (1) flow from the 

regulated gas tank and (2.) flow from breathing into the inlet tube. The flow pump used 

in the previous investigation was used for breath testing only. 

 

2. The results of this investigation demonstrate that forcing the flow to impinge onto the 

active sensor surface using a variety of approaches produced marginally different results 

compared to the original design which allows for flow parallel to the active sensor 

surface. However, these results were obtained at low flow rates without the pump that 

was used in the initial investigation. 

 

3. The CO2 sensor response is greatly dependent on flow rate. The response without 

augmenting the flow rate with a pump (about 25 sec.) is not adequate for diagnostic 

purposes. With a pump, the response can be as low as 2.5 sec. 

 

4. Other factors, such as the length of tubing between the sample and the sensor, or sensor 

housing volume, could improve sensor performance, although sensors will be needed to 

find accurate gas concentration. 

 

5. Testing of the sensor will need to be carried out to determine the ideal placement of 

sensors in the ventilator to solve this problem.

Presenting Author: John Schofield Villanova University- College of Engineering

Presenting Author Biography: Hi! I&#39;m John Schofield, an Undergraduate Junior at Villanova University majoring in Mechanical Engineering, minoring in Computer Science, while also working as an Undergraduate Research Assistant at Villanova&#39;s Birle/Ortega Laboratory for Advanced Thermal and Fluid Systems. In the lab this spring, I worked on the sensor team of the NovaVENT project, fabricating low cost, accessible emergency ventilators for the COVID-19 Pandemic. In this investigation, I designed several 3D Printed prototype CO2 Sensor Housings and gathered experimental data on each to enhance the sensor&#39;s response and more accurately monitor the patients health.<br/><br/>This Summer I had the opportunity to successfully design, fabricate, and test National Science Foundation sponsored research of Enhanced Pool Boiling for High Heat Flux Electronics Cooling. This current work has shown using a submerged synthetic jet has an immediate effect of enhancing the heat transfer from the target &#39;CPU&#39; surface. <br/><br/>Outside of the classroom and laboratory, I&#39;m on the ASME Executive Board at Villanova, where I help organize and facilitate 2-3 events around campus every semester, from Solidworks competitions to Industry site visits. I&#39;m also on the Club Running Executive Board at Villanova, where I&#39;m Apparel Manager, ordering and delivering club apparel.

Authors:

John Schofield Villanova University- College of Engineering
Elsaid Youssef Villanova
Alfonso Ortega Villanova University