The smart gown activity was funded in part by NIH R25EB013029

2012 WIEP EDGE Camp BME Activity
Overview of activity:
The Smart Gown activity is a three day (9 total contact hours) mini-design project for the
Women in Engineering at Purdue’s (WIEP) Exciting Discoveries for Girls in Engineering
(EDGE) camp. Each team worked to develop a “smart” gown which could replace traditional
hospital gowns and measure physiological signals (heart rate and respiration). To accomplish the
task, a three day (3 hours per day) structure was developed for the project.
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Day 1 consisted of introducing the girls to biomedical engineering, brainstorming ideas
for important physiological signals to measure, equipment overview, and another
brainstorming session resulting in a sketch of how to create the gown.
Day 2 involved the majority of building and testing the electrical circuits used to acquire
the physiological signals and also included decorating the gowns and initial thoughts on
creating a scientific style poster to display their results.
Day 3 began with an introduction to giving a professional presentation (to be used in the
poster presentation later) and continued with developing the poster; the day concluded
with the girls presenting their posters and solutions to their parents during an EDGE
reception.
Activity:
“SMART” Gown
The goal of this project is to develop a “SMART” hospital gown that can measure patient vital
signs without encumbering movement.
Timeline:
Day 1
1. Introduction to Biomedical Engineering (BME) (15 min): provide an overview of the
BME field and key research areas at your institution
2. Intro project (15 min):
a. Introduce the need for physiological signal measurement
b. Discuss how current devices used in hospitals involve many connections which
make it difficult for a person to walk around and that it would be convenient if the
gown were able to make the measurements without the need for lengthy
connections that hinder movement.
c. Ask participants to suggest signals to measure based on what they have seen in a
hospital or on TV (e.g., heart rate, pulse oxygenation, breathing rate, blood
pressure)—(we created a list on a chalkboard as the participants called out
options).
The smart gown activity was funded in part by NIH R25EB013029-02
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d. Briefly discuss signals mentioned and indicate the focus of the project is on
electrocardiogram (EKG) and respiration rate.
Technical background (5 min)
a. Discuss physiological signal size and the need for gain (amplifier)
b. Discuss physiological signal frequency and the need to isolate with filters
c. Demo on EKG
i. Use lead II configuration and briefly explain set up and electrode
connection points
Circuit-building: breadboards and components should be with participants at this point
(20 min)
a. Show how connections on a breadboard are made. Provide a simple circuit and
show how it is connected on the breadboard. This can be done with PowerPoint
or by drawing out on a chalkboard.
b. Identify the components the participants will be using; provide pictures or have
samples available for viewing
c. Sketch a Wheatstone bridge circuit on board and discuss how it is typically used
(to make small changes more easily seen).
d. Have participants connect a Wheatstone bridge on their breadboard
Signal acquisition (10 min)
a. EKG: how are these signals transmitted from the body to the circuit
i. Briefly discuss electrodes, conductive materials that allows signal to
transfer from body to circuit
b. Respiratory rate: transducer
i. What is a transducer?
ii. Transducer in this experiment is a strain gauge
1. Strain gauge can be made by filling stretchable latex tubing with
conductive gel.
2. Discuss principle involved and relate to Wheatstone bridge:
resistance increases with decreasing diameter (diameter decreases
as tube is stretched)
Release participants to brainstorm how to build the device and sketch out a design/plan
Review design plan with facilitator
Start building
Day 2
1. Finish building
2. Discuss key topics to include on a poster (10 min)
3. Intro on testing (20 min)
a. EKG: Does the EKG signal look correct? Is it too small/big (adjust gain)? Is the
size ok but the shape doesn’t look correct (adjust filtering)? How does subject
movement affect the signal? Is there a way to stabilize the electrodes to reduce
movement artifact? More advanced, if time permits, check heart rate response
(count R waves in given time) against measuring pulse (heart rate). Have students
The smart gown activity was funded in part by NIH R25EB013029-02
do exercise to increase heart rate and ensure circuit can correctly show the new
signal.
b. Respiratory rate: measure resistance of strain gauge with a multimeter (set to
ohms). How much does the resistance of the strain gauge change when stretched?
Is a short or long strain gauge better (for larger changes in resistance)?
c. Wheatstone bridge circuit: does the change in output (on oscilloscope) correspond
to breathing? Is the signal easy to see? If it is small what can be done (amplify)?
4. Run tests (among several individuals)
a. After circuit has been tested, acquire test signals from other individuals to show
circuit works for different people. Is the reading correct for each person?
5. Decorate device, reduce wires, and identify (if time permitted) a way to eliminate wires
(make wireless)
6. Start posters – sketch on paper first before working on poster board
Day 3
1. Intro on giving a professional presentation (20 min)
2. Final touches on device decoration and posters
3. Present poster and demonstrate gown to parents
Supplies:
Smart Gown Build:
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Oscilloscope
Power supply
Function generator (for test signals)
Grass amplifier
a. Alternative to using a Grass amplifier to acquire EKG signal
i. Purchase and wire an instrumentation amplifier chip such as Analog
Devices AD 620 from Mouser or Digikey
ii. For safety, power AD 620 with two 9 V batteries (connect negative
terminal of battery 1 to positive terminal of battery 2 (this creates a virtual
ground); use the positive terminal of battery 1 as your positive supply and
the negative terminal of battery 2 as your negative supply)
iii. Construct an active bandpass filter (1-200 Hz) to acquire the EKG signal
5. Hospital gowns
6. Resistors (and capacitors if filters must be built)
7. Thermistors (Digikey part# 317-1258-nd)
8. Latex tubing (1/8” ID x 3/16” OD; 1/32” wall thickness) (VWR part no. 62996-350)
9. Electrode gel (Amazon Spectra 360 electrode gel by Parker Laboratories—double check
this box is under desk that is below window into sophomore lab)
10. EKG electrodes (Emergency Medical Products, Part no. SF403)
11. 1” wide elastic band
The smart gown activity was funded in part by NIH R25EB013029-02
12. Electrical wire (22 AWG for breadboarding)
13. Breadboard
14. Sewing needles and thread
15. Hot glue gun and hot glue
Personalizing the Device:
1. Fabric paint
2. Paste jewels
Poster Presentation
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Poster boards
Markers
Camera
Printer
The smart gown activity was funded in part by NIH R25EB013029-02

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