1. Intracranial Pressure Monitor
Mike Socie – Leader
Becky Koszalinski – Communicator
Justin Lundell – BSAC
Dan Frost – BWIG
Client:
Josh Medow, M.D. UW Hospital
Advisor:
Professor Naomi Chesler, UW-Madison

2. Presentation Outline Problem Statement Background Information
Current Methods
Design Constraints
Possible Designs
Future Work

3. Problem Statement ICP Monitor should:
Measure pressure of intracranial fluid
Produce accurate recordings
Have a low drift rate
Be small, convenient to patient
Be MRI compatible

4. Background: Need Why is this technology needed? Shunt failure 17%
Hydrocephalus – ventricle blocked
Symptoms not specific for diagnosis
Children don’t report symptoms
Frequent CT scan testing dangerous

5. Background: Current Methods
Current methods include:
CT scan
Ultrasound
Exploratory surgery
Shunt taps
Improved methods would allow:
At home use
Continuous monitoring
Measurement without radiation
Accessibility to patient
Ease of testing for children
Cost effective testing

6. Background: Power Sources
Induction
Powers device non-invasively
Direct current power
Wires through skin -> infection
Battery
Finite lifespan -> replacement surgeries

7. Design Constraints Small, implantable, durable Bio and MRI compatible
Low power
High precision (1 mmHg error)
Low drift rate (<1% annually)
Send output for reading

8. Design Options Resonant Coils Component Based Two transducer options
Resistance based
Capacitance based
Two signal output options
RFID tags
Voltage to frequency converter

9. Design 1: Resonant Coils
Advantages:
Fewer parts than component based design
Easy signal transmission
Disadvantages:
Undetermined drift
Durable?
voltage

10. Design 2: Component Based

11. Design 2: Component Options
Transducers
Resistance based
More available
High drift
Not power efficient
Capacitance based
Less available
Low drift
More power efficient
Signal Output
RFID tags
Require less parts
Passive technology
Voltage to freq. converter
Require multiple parts
Require power

12. Design Matrix Weighting Resonant Coils Components: Resistance & RFID
Resistance & V to F converter
Capacitance & RFID
Capacitance & V to F converter
Power Consumption
1 / 6 5 3 2 4
Durability
Precision
Drift 1
Ease of Construction
2 / 6
Total:
1 * 5
3.8
3.0
2.3
3.7

13. Future Work & Challenges
Select and purchase materials
Construct prototype
Test drift, accuracy, and durability

14. References Dr. Josh Medow, Neurosurgery, UW Hospital
“Measuring Strain Gauges” National Instruments.
“Wheatstone Bridge Background” dwiarda.
“Wheatstone Bridge” Wikipedia.
Webster, John. Medical Instrumentation: Application and Design 1st Edition