ENGINEERING WORLD HEALTH TEMPERATURE TESTER Team: Carly Brown, Sarah Offutt, Ryan Thome, Sasha Cai Lesher-Perez BME 201 May 5, 2006

Client: John Webster, Ph.D. Dept. of Biomedical Engineering University of Wisconsin Advisor: Paul Thompson, Ph.D. Dept. of Biological Systems Engineering University of Wisconsin

Abstract Our project, from Engineering World Health, was to design a device for testing the temperature in an incubator or water bath. The temperature tester must signify a deviation of temperature of 0.05 ° C from 37 ° C. The greatest restriction placed on our design was the cost of the device, $3.00 per unit. The final design is based on a circuit that used a Wheatstone bridge with a thermistor, a potentiometer and a dual comparator that is connected to two LEDs to alert the user of temperature deviations. The circuit is incased in PVC piping and epoxy, and features a removable battery. Future work on the project includes increasing battery life and decreasing size.

Problem Statement We will design a temperature tester that indicates changes in a water bath or incubator temperature by more than half a degree from a specified temperature of 37 ° C

Engineering World Health Non-profit organization Non-profit organization Medical supplies to third world countries Medical supplies to third world countries Purpose: develop devices that are cost-effective and user friendly Purpose: develop devices that are cost-effective and user friendly

PDS Summary Size: 1”x1”x4” Size: 1”x1”x4” Water Resistant Water Resistant $3.00 per unit in quantities of 500 $3.00 per unit in quantities of 500 Accuracy:.1° C Accuracy:.1° C Operating Temperature: 17-45° C Operating Temperature: 17-45° C

Background: Uses Water Baths Water Baths Heating beakers Break up kidney stones Incubator Incubator Premature babies Biological cultures Drug stability testing jpg

Background: Current Products Current Products Current Products Ice-Box Alarm ThermometerIce-Box Alarm Thermometer Audible alarms and flashing LEDs Audible alarms and flashing LEDs Pre-set temperature range Pre-set temperature range $19.00 $19.00 Traceable Alarm ThermometerTraceable Alarm Thermometer Audible alarm Audible alarm ±2° C accuracy ±2° C accuracy $30.76 $

Circuit 9 V Battery 9 V Battery 100kΩ Thermistor 100kΩ Thermistor 10kΩ Potentiometer 10kΩ Potentiometer Comparator Comparator LEDs LEDs Switch Switch

Circuit Cont. Battery Life: 120 hours Battery Life: 120 hours Thermistor placed in water Thermistor placed in water Potentiometers are adjusted Potentiometers are adjusted Comparator circuits are opened at deviated temperatures Comparator circuits are opened at deviated temperatures When comparator circuit is opened the lights turn on When comparator circuit is opened the lights turn on

Casing PVC pipe PVC pipe Caps Caps Holes drilled for LEDs and Switch Holes drilled for LEDs and Switch Epoxy Epoxy 1 ½” x 3” 1 ½” x 3”

Casing Cont. Features Features Thermistor probeThermistor probe Protection for the thermistorProtection for the thermistor Testing Testing Submerged in water for 2 daysSubmerged in water for 2 days 3 tests3 tests

Project Expenses Price per Unit Price per Unit Circuit $2.36Circuit $2.36 Casing$0.22Casing$0.22 Manufacturing$0.44Manufacturing$0.44 Total$3.02

Future Work Minimize size Minimize size Dual CapacitorDual Capacitor DiameterDiameter Increase battery life Increase battery life Device to allow attachment to vertical surfaces Device to allow attachment to vertical surfaces

References Allina Hospitals & Clinics. (2005, March). Laser Lithotripsy. Retrieved February 12, 2006 from Caplugs. (2003). PDE series. Retrieved April 7, 2006 from Castle Wholesalers. (2004). PVC Pipe 1 ½” x 10’. Retrieved April 23, 2006 from %20%26%20CPVC&subsubcat=PVC%20Pipe Circuit Specialist, Inc. (2003). Online Catalog: circuit board 6” x 9”, Etching Powder, Flux Remover Pen. Retrieved April 23, 2006 from Control Company. (2006, January). Traceable Alarm Thermometer/Alarm Timer. Retrieved February 5, 2006 from Discount Office Supply. (2003). Sharpie Marker. Retrieved April 24, 2006 from Engineering World Health. (2006). Proposed Projects. Retrieve January 25, 2006 from FW Online. Latex. Retrieved April 24, 2006 from Jameco Electornics. (2005). Online Catalog. Retrieved March 15, 2006 from New York Distributors. (2006). Panasonic Batteries: 9-volt. Retrieved April 15, 2006 from Pacific Link. (2005, September). Incubators. Retrieved February 12, 2006 from Research Products International Corporation. (2006). Alarm Thermometer Monitor. Retrieved February 5, 2006 from Superkleen Direct. (2005). Epoxy. Retrieved April 26, 2006 from ThermoWorks. (2004, November). Low Cost Digital Thermometers. Retrieved February 5, 2006 from Webster, John G. (2003). Bioinstrumentation. Indianapolis, IN: John Wiley & Sons Inc.