Transcript Tested liquid flow rate - Computer

Lucas Vitzthum, Tyler Lark, Nick Harrison, Fan Wu
Advisor: Paul Thompson, Ph.D. Client: John Webster, Ph.D.
Abstract
Medical aspirators are suction devices used to remove mucous
and other bodily fluids from a patient. Many developing world
hospitals do not possess aspirators because they can not afford or
repair the current devices on the market. The goal of this design is to
create a less expensive, locally repairable, and less power dependant
alternative to current medical aspirators. The design should provide
the broadest range of possible uses for developing world hospitals.
Final Design
Costs
Table shows costs and 3rd world source for each part used in the design.
The final design of our device is comprised of a 12 V car battery, fan motor, diaphragm
system, fluid collection chamber, and tubing with an autoclavable tip.
Part
1” PVC pipe
Power source to radial motion:
Lab Gloves
$.28 x 4 = $1.12 Operating room
Source: medicalsupplyco.com
DC Fan Motor
12 V Battery
Pipet Tip
$.04
Plastic Syringe
2x4 Lumber
Attached to the fan motor is a bolt and washer.
A string is tied to the washer and fed through a
mounted syringe to keep the string pull as linear
as possible. The other end of the string is
attached to the diaphragm system.
Water Bottle
$.75
Operating room
$.80/foot x 6 feet Natural environment
= $4.80
Abandoned building
$.20 x 8 = $1.60 Abandoned building
Source: Home Depot.com
Construction material
$4.00
Household item
Source: Walmart.com
Tygon® Tubing
$1.09/foot x 6
feet = $6.54
Operating room
Salvaged automobile
Source: medicalsupplyco.com
2 Ω Power
Resistor
String attached to washer and fan motor
$1.09 x 2 bulbs
= $2.18
Two 60 watt light bulbs (wired in parallel)
Source: Home Depot
Diaphragm system:
Check Valve
A cylindrical lid from a food container is the base of
the diaphragm. A rubber balloon is stretched over
the base of the diaphragm and a string is tied to the
tip. A layer of rubber glove is super-glued to the
balloon and over the string for added support.
Wire
Total
The output check valve is the stem of a balloon
glued half shut and stretched over one end of
the PCB pipe. The input check valve is a oneway valve obtained from the bulb of a
sphignomonometer, located in the tubing adapter
attached to the other PCB pipe opening.
Collection chamber, tubing,
and suction tip
Tubing adapters are taped or fitted
to connect the input check valve to
the collection chamber. A hard
plastic water bottle is used as the
collection chamber, which is then
connected to an autoclavable pipet
tip.
Prototype Testing
Tested vacuum generated:
• Used monometer gauge
• Generated a 76 mmHg vacuum
$49.50*
Future Work
•
•
•
•
•
•
Improve maximum vacuum and flow rate
Add variable resistor to control rate of aspiration
Improve diaphragm strength and durability
Minimize overall size
Develop instructions to build locally
Contact third-world country hospitals and clinical engineers to
implement device and begin use
• Create proposal to send to EWH for funding
References
Gomco Suction Equipment & Accessories Guide. 2006. Gomco by Allied.
From http://www.alliedhpi.com/images/z21-00-0000.pdf
1.8
Hill, D. (2005). Duke engineering program improves hospital conditions in
developing countries. Retrieved 4/12, 2007, from
http://www.dukenews.duke.edu/2005/09/DEWH.html
1.6
1.4
Flow Rate (L/min)
Tested liquid flow rate:
• Aspirator was run for 20 second intervals
• Recorded collected volume
• Flow rate was calculated as liters/minute
• Averages were computed with different sized tip
openings
Sphignomonometer
Source: Ebay.com
Operating room
$.15/foot x 2 feet Salvaged automobile
= $0.30
Electronic devices
*Projected cost is a high estimate as many of the materials can be salvaged free of cost.
Tubing and Collection Chamber:
Diaphragm and check valves
$.99
Source:Walmart.com
Liquid Aspiration Flow Rate
• Completely manufactured from locally available parts and expertise
• Cost: less than $100
• Autoclavable suction tip
• Flow rate range of 0 – 30 lpm.
• Vacuum pressure range of 0 – 550 mmHg
• Must be safe for use in human surgeries
• Reliably provide suction throughout an entire surgery or operation.
• Must not interfere in operating room procedures or with staff.
• Run and power device with varying electricity and limited resources.
Hospital lab
Source: Ax-man Surplus
Nails/Screws
Source: www.medfinity.com
Design Criteria
Salvaged automobile
Source: Fisher Catalog
Radial to linear motion:
One-way valves:
• Current devices inaccessible to developing world hospitals
 Too expensive
Current Medical Aspirator
 Too specialized
 Not locally repairable
• Currently on the market:
• Gomco®
• Allied Health Care
• Schuco
$20
Source: Moemart Salvage
Statement:
Motivation:
Salvaged automobile
Source: Home Depot
Problem Statement
Design an inexpensive medical aspirator that can be built and repaired from locally
available parts and expertise for use in developing world hospitals.
$5.00
Source: Moemart Salvage
Overall design
• Medical aspirators:
 Found in almost any hospital, ambulance, or dental clinic in the U.S.
 Suction devices used to remove mucous, blood, or other bodily fluids
 Generally include disposable suction tips and a removable collection receptacle.
 Generally powered by 120V AC outlets, batteries, or a combination of both
 Designed for use in modern, state of the art medical environments.
 Sizes can range from hand held devices to larger stationary surgical units
•Third world hospital conditions are radically different
 Inconsistent electricity
 Lack of medical professionals.
 Limited space
3rd World Source
Plumbing equipment
Source: Home Depot
The power source of our design is a 12 V car
battery which can be charged in a variety of
ways. This is connected in series with a 2
ohm power resistor and a heater fan motor.
The power resistor can be replaced by a
system of light bulbs to obtain the same
resistance and reduce the motor speed.
Background
Cost
$1.09/foot x 2
feet = $2.18
1.2
1
Aspirator suction machine. 2007. From
http://www.medicalsupply4u.com/prodList.asp?idCategory=112&show
Filter=0&idProduct=51
0.8
0.6
0.4
0.2
0
Small Tip
Large Tip
Autoclavable Tip Size
Figure 1: Bar graph representing flow rate (L/min) of water
collected through suctions tips with small and large openings.
Error bars represent SE (n=6)
Acknowledgments
Thanks to Amit Nimunkar, Frank Fronzcak Ph.D., Douglas
Kinter, Paul Thompson Ph.D. and John Webster Ph.D.