Tested liquid flow rate: Aspirator was run for 20 second intervals Recorded collected volume Flow rate was calculated

1. Overall design String attached to washer and fan motor 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) Diaphragm and check valves Current Medical Aspirator Collection chamber, tubing, and suction tip Source: www.medfinity.com Engineering World Health: Medical Aspirator Lucas Vitzthum, Tyler Lark, Nick Harrison, Fan Wu Advisor: Paul Thompson, Ph.D. Client:John Webster, Ph.D. Abstract Final Design Costs 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. Table shows costs and 3rd world source for each part used in the design. 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. Power source to radial motion: 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 • 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 Radial to linear motion: 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. Diaphragm system: 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. Problem Statement *Projected cost is a high estimate as many of the materials can be salvaged free of cost. Future Work • Statement: • Design an inexpensive medical aspirator that can be built and repaired from locally available parts and expertise for use in developing world hospitals. • Motivation: • Current devices inaccessible to developing world hospitals • Too expensive • Too specialized • Not locally repairable • Currently on the market: • Gomco® • Allied Health Care • Schuco Tubing and Collection Chamber: 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. • 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 One-way valves: 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 one-way valve obtained from the bulb of a sphignomonometer, located in the tubing adapter attached to the other PCB pipe opening. Prototype Testing References Gomco Suction Equipment & Accessories Guide. 2006. Gomco by Allied. From http://www.alliedhpi.com/images/z21-00-0000.pdf 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 Aspirator suction machine. 2007. From http://www.medicalsupply4u.com/prodList.asp?idCategory=112&show Filter=0&idProduct=51 • 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 • Tested vacuum generated: • Used monometer gauge • Generated a 76 mmHg vacuum Design Criteria • 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. Acknowledgments Thanks to Amit Nimunkar, Frank Fronzcak Ph.D., Douglas Kinter, Paul Thompson Ph.D. and John Webster Ph.D.