1. Measuring Permittivity
of Bodily Fluids
Project Team: Michael Wilkins and Austyn Turner
Graduate Student Joe Pearson
Advisor: Kent Chamberlin

2. Problem
“Most vaccines are delivered by the intramuscular or subcutaneous routes using a needle and syringe.” – The World Health Organization
Finding electrical characteristics of fluids
Permittivity
Viscosity of vaccines
Money and time wasted

3. Solution Dielectric heating using radio frequency
Two electrodes as parallel plate capacitor
Thermistors to measure temperature
LC circuit to obtain resonance
Arduino to calculate and graph data

4. Lab Constructed Capacitor
A simple two electrode configuration
Materials
Packaging tape with thickness of 60 microns on each copper electrode
Total of 120 microns or .12 mm
2 Copper electrodes measuring 20 by 40 mm each
Adjustable calibration stand with precision to 10 microns
Stronger electric field at smaller distances
Capacitance reading of 85pF at 160microns of seperation
Area of plates = 800 mm^2
Minimum distance = .7 mm

5. Capacitive Heating
A varying sinusoidal voltage applied to the electrode creates an electric field between the plates
Polar molecules of the fluid align with the changing field
Frictional forces dissipate heat
Higher frequency= faster rotation of molecules

6. Thermistors
Two thermistors: one placed within the control fluid, and the other within the fluid being sampled
Resistance of thermistors changes with temperature
A current gets sent through the thermistor then through a series of op amps and a precision resistor to translate into a 0-5V analog signal
Read using the Arduino uno with a 10 bit accuracy
Temperature readings were calibrated with a stirred water bath

7. LC circuit
Tank circuit used to deliver maximum power to capacitor at resonant frequency
Fresonance= 1/(2*π*sqrt(LC))
Resonant frequency should be within radio frequency bandwidth
Inductor is needed to cancel capacitor reactance to give a pure resistive load

8. Oscillator
Sweep through frequencies to find resonant frequency of test fluid
Possible options:
VCO
Programmable function generator

9. Budget Voltage controlled oscillator design budget
Materials
Price ($)
Quantity
Expense ($)
Arduino Uno
29.95 1
Arduino USB cord
9.95
Thermistors
3.29 2
6.58
Calibration stand
10.00
Basic components (wire, resistors)
8.00
Operational Amplifier (LF356)
0.99
.99
Total
$ 65.47
Voltage controlled oscillator design budget
Materials
Price ($)
Quantity
Expense ($)
Comparator (LM311)
0.29 4
1.16
LCD Display
9.95 1
MOSFET (2N7000)
0.09
0.36
Basic components (wire, resistors)
10.00
Operational Amplifier (LF356)
0.99
3.96
Total
$ 25.43
Total cost of current configurations + VCO : $ 90.90

10. Fall Schedule

11. Spring Schedule

12. Questions?