Zainab A. Hussein and Shannon Hartzell Faculty Mentor: Zoe Boekelheide

Sensors in an Alternating Magnetic Field for Magnetic Nanoparticle Hyperthermia Cancer Therapy

Process:

•Thermal evaporation:

•30ÅCr sticking layer

•500-2000ÅCu

•Photolithography

Design and Fabrication

Sample Au thin film resistive sensor on a thermal oxide silicon substrate

Inductive and Resistive sensor on glass slide

Temperature sensor

heat

moment flips

magnetic field

Typical parameters: ▪ 100-500 kHz ▪ 0.01-0.1 Tesla ▪ 33-42°C

Nanoparticle heating curves 10 nm Fe3O4 nanoparticles in H2O, 20 mg/mL, from Liquids Research. Heating in max 0.04 T field

Summary: Magnetic nanoparticle hyperthermia is a promising method of cancer therapy. Accurate characterization of nanoparticle heating is required to further this technology. One problem is that metallic sensors undergo their own eddy

current heating in an alternating magnetic field. We explore the useful limits of metallic sensors in the alternating magnetic field environment. Patterned thin film sensors in particular may be advantageous, as the heating is size dependent and

patterned thin films are scalable into arrays of sensors.

a. Resistive Sensor Design (thermometer)

b. Inductive Sensor Design (magnetic field

sensor)

Alternating magnetic field generator (Easyheat)

A promising method of CANCER THERAPY

How it works:

•Magnetic nanoparticles injected into tumor

•Alternating magnetic field applied

•Nanoparticle moments flip

•Energy released as heat

•Tumor cells damaged 43-44 °C

•Healthy cells damaged ~45 °C

Future work will focus on characterizing Au thin film sensors of varied thicknesses and stroke sizes as metal heating in alternating magnetic field (AMF) is a function of size. Also, a careful calibration and scale down of both resistive and inductive sensors.

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0.00E+00 1.00E+03 2.00E+03 3.00E+03 4.00E+03 5.00E+03 6.00E+03 7.00E+03

Tem

pera

ture

(d

eg

rees C

)

Time (s)

Keithley Temperature Plot of ⊥ Au sensor on glass substrate

Turn on

chiller Turn on

current

60.9A

Rapid self-

heating of

sensor due to

eddy currents

ΔT =

20.4˚C

237.3A

300.3A

Turn off

current

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0.00E+00 1.00E+03 2.00E+03 3.00E+03 4.00E+03 5.00E+03 6.00E+03 7.00E+03

Tem

pera

ture

(d

eg

rees C

)

Time (s)

Keithley Temperature Plot of || Au sensor on glass substrate

Turn on

chiller

Turn on

current

60.9 A

300.3A

ΔT =

5.6˚C

237.3A

Turn off

current

Au sensor ⊥ to B

Au sensor || to B

Position of Au sensor

Keithley Data (ºC)

Opsens Data (ºC)

Net ΔR (Ω)

Sensor | | to B 5.6 7.2 1.04E+02 Sensor ⊥ to B 20.4 9.1 3.89E+02

Results:

Opsens data:

• Temperature measured at the tip of the fiber

optic, which is near the sensor.

• Data collected better at estimating the

surrounding heating of the various components

used with the sensor.

Keithley data:

• Temperature of sensor directly measured by

passing current through sensor, making it a more

accurate measurement of sensor self heating.

Results:

Oscilloscope displaying the two signals in phase

Magnetic field sensor:

Au sensor dunked in Liquid N2

The same Au sensor tested in alternating magnetic

field was dunked in liquid Nitrogen in to observe the

resistance relation with change in heat in the cold

extreme:

• Correct linear resistance-temperature relation

• In room temperature the dunked sensor

returned to the original 9kΩ resistance

•Lafayette College Excel Program for funding for Zainab Hussein

and Shannon Hartzell

•Department of Physics

•Department of Biomolecular and Chemical Engineering for use

of photolithography equipment

•Department of Chemistry for use of thermal evaporator

•Department of Physics Technician Michael Karner for fabrication

of magnetic field coils and sample holders

•National Institute of Standards and Technology for Fe3O4

nanoparticle sample

Thin film magnetic field sensor compares well to commercial magnetic field probe: • Signals in phase • Correct magnetic field

dependence

In situ magnetic field measurement of inductive sensor and commercial probe and their corresponding signal output

Temperature sensor:

Magnetic Nanoparticle Hyperthermia

Patterned thin film sensors

Future Work

Acknowledgements: