Mass Flow Controller System Client: Brad Hodgeman– Instrumentation Specialist, Comparative Biosciences Advisor: Professor Emeritus John G. Webster Team Members: Aaron Huser, Cole Kreofsky, Dana Nadler, Joe Poblocki

University of Wisconsin - Madison Biomedical Engineering Design Courses INTELLECTUAL PROPERTY STATEMENT

Problem Motivation  Brad Hodgeman researches hypoxia and hyperoxia with rats at the Veterinary Science Building.  Current mass flow controllers are too inaccurate, and the software is outdated.  There are undesirable, manual aspects to protocol that need to be eliminated.

Problem Statement The purpose of this project is to design a system that can create a reproducible and accurate hypoxic/hyperoxic environment with the capability of oscillating between various concentrations of oxygen and nitrogen.

Background  Hypoxia and hyperoxia are atmospheric conditions, where the oxygen level deviates below or above normal (21%) concentration, respectively.  Hypoxia is a form of respiratory distress which induces certain physiological responses by the neuro-respiratory system. These responses have been associated with SIDS, sleep disorders, spinal cord injury, etc.

Mass Flow Controllers  Mass flow controllers often aid in hypoxia research due to their ability to alter Oxygen concentrations to desirable levels for testable consequences.

Current Gas Control System  Computer controlled Command Module (HyperTerminal Software)  Four Analog Mass Flow Controllers  Two Manual Mass Flow Controllers  Four Chambers

Design Constraints  Variable gas concentrations and flow rates through a chamber  Software with an easy to use interface and customizable features  Accurate mass flow controllers, digital or analog  Uniform tubing resistance  Low sound level  Capability for further expansion

Software Development  LabVIEW  Graphical programming environment made for engineers and scientists  Client has had previous experience using DASYLab – a program similar to LabVIEW  Ability to customize programs easily and efficiently  Variety of open source examples of current programs available

Main Areas of Focus  Mass Flow Controller Manufacturers  Sierra Instruments – Series 100 Smart-Trak™  Advanced Energy – Aera® Mach One  Mykrolis – Intelliflow ™ II  Interface types  Analog  Digital  DeviceNet  RS485  RS232

Manufacturer Matrix CompanyAccuracy Response TimePrice Customer ServiceFlow RangeTotal Advanced Energy+/- 0.5% (4) <= 250 ms (5) $ US (3)(3)3 L/min (2) 17** Mykrolis +/- 0.25% sp plus 0.35% fs (3)1 sec (3) $ US (2)(3)5 /min (5) 16 Sierra Instruments +/- 0.7% of reading + 0.3% fs (2)2 sec (2) $ US (4)(4)6 L/min (4) 16 Low=1 - 5=High **The Numbers Don't Lie!

Digital vs. Analog Digital  Accuracy is a function of set point (sp)  Multiple gas calibration curves  Multiple set point calibration  More cost efficient Analog  Accuracy is a function of full scale (fs)  Manual individual gas calibrations

Digital Interface DeviceNet  Most Expensive  Too sophisticated for this system RS232  Least Expensive  Ergonomically incompatible RS485  Moderately Expensive  Ability to daisy-chain cables

System Design LabVIEW software, RS485 interface and AE MFCs

Questions Any Questions?