1. Padraic Casserly, Andrew Dias, Joey Labuz, Joel Webb
Ventilation Monitor
Padraic Casserly, Andrew Dias, Joey Labuz, Joel Webb

2. Problem Statement Design a ventilation monitor that can:
Be worn on a firefighter’s chest
Monitor respiration rate
Wirelessly transmit data
Save lives

3. Background Need for device
Asphyxiation is the third leading cause of firefighter death
123 asphyxiation deaths in last decade
Inductance Plethysmography
Used to measure change in lung volume
L = NΦ / I

4. Current Devices Vivometrics Vivoresponder MSA TxR ICM System
$2500-$8000
MSA TxR ICM System
$1800 base price
Ambulatory Monitoring Inc.
$70
MVAP
$260
Ambulatory Monitoring Inc. Catalog

5. Design Constraints Send signal indicating firefighter respiration
Fits chest sizes 30” to 50”
Protected from moisture
Able to withstand temperatures of 110° F
Comfortable
Less than one pound

6. Chest Strap Design
4.00”

7. Design 1: Inductive Plethysmographer with Colpitts Oscillator
f  L-1/2
Time varying frequency converted into voltage

8. Design 2: Inductance Plethysmographer with Low-pass Filter
Chest strap functions as inductor (L)
Vout = VR
fc  R/L, so choose R and L such that frequency is very close to fc

9. Design 3: LVDT Linear Variable Differential Transformer
Reliable and Accurate
Too Costly

10. Design Matrix Weight Colpitts Oscillator Low-pass Filter LVDT Safety20 18 15
Signal Strength 25 17 10 22
Comfort 13 8
Cost 19 4
Manufacturability/feasibility 16 12
Total
100 79 72 67

11. Future Work Order materials Build prototype of final design
Test prototype
Further investigate transmission technology

12. References
Cohen et al “Design of an Inductive Plethysmograph for Ventilation Measurement.” Physiological Measurement. Vol 15, No 2, pp
Cohen, Neal H and Shaughnessy Thomas E “Respiratory Monitoring.” Baillière's Clinical Anaesthesiology, Vol. 10, No. 1, pp
FireSite. “Firefighters in peril: monitoring heart rate, breathing, and movement.” Research Proposal H-SB , #
Hett, D.A and Jonas, M.M “Non-invasive Cardiac Output Monitoring.” Intensive and Critical Care Nursing. Vol. 20, No. 2, pp ScienceDirect.
International Firefighting News “Daily Firefighting News and Photos.” <
Macro Sensors “LVDT Basics.” <
Omega “LVDT: Economical AC Displacement Transducers.” <
OpenSystems Publishing “Multichannel LVDT Signal Conditioner Supports Position Measurement Applications »
Rosenthal, Justin. “Inductance Plethysmography.” <
U.S. Fire Administration “Firefighter Fatalities in the United States in 2006.” <
Webster, John G Bioinstrumentation.
Weinberg G.M. and Webster J.G “Measuring Human Ventilation for Apnoea Detection Using an Optical Encoder.” Physiological Measurement. Vol 19, No. 3, pp
Williams et al Inductive Plethysmographic Transducers and Electronic Circuitry Therefor. US Patent, 5,331,968.