Temperature Sensing Options for Magnetic Nanoparticle Frequency
Response Profiles in an RF Field.
Table of Contents
Introduction
Fiber Optical Temperature Sensors
Temperature Sensing for In Vivo / In Vitro Experiments
Compatibility with magneTherm Technology
About nanoTherics
Introduction
Different experiments require different types of sensors in order to measure and record the rate of
change of temperature in magnetic nanoparticles exposed to an RF field.
In this article, we discuss the temperature sensor options available with the magneTherm system
from Nanotherics. The most cost effective option would be a thermocouple for calorimetric
experiments. However, thermocouples are prone to electromagnetic interference, so the signal to
noise ratio will vary depending on the subjected alternating magnetic field.
Values recorded for initial and final temperature readings before and after exposure to alternating
magnetic fields, along with an appropriate control/blank sample, can be used to calculate the rate of
change over time and derive an accurate SAR value.
Figure 1: Type T thermocouple and electronics
20 mg/ml maghemite (50 nm) subjected to 522 kHz/24 mT - Type T
thermocouple
AMF OFF
Temperature (celsius)
70
60
signal
with noise
50
signal
without noise
40
30
AMF On
1
39
77
115
153
191
229
267
305
343
381
419
457
495
533
571
609
647
685
723
761
799
837
875
913
951
989
1027
1065
1103
1141
1179
1217
1255
20
Period (seconds)
Figure 2: Signal and noise with a thermocouple in a magneTherm system – 522 kHz used as noise
shown is at a maximum at this frequency and reduces above or below this.
Fibre Optical Temperature Sensors
These difficulties can be eliminated by using a more appropriate sophisticated temperature sensing
technology, widely known as fibre optical sensors. Temperature can be measured using a modified
fibre which displays evanescent loss that varies with temperature, or by analysing the Raman
scattering of the optical fibre.
As there is no voltage or metal involved here, these sensors are not prone to electric and magnetic
interference. These more sensitive sensors are costly, but do provide accurate measurements, and
are fully compatible with the magneTherm system.
Multichannel optical sensing platforms can also be deployed with magneTherm systems to measure
temperature at various points within the sample simultaneously. This option is far more suitable for
calorimetric experiments in the magneTherm system.
Figure 3: Single channel and multichannel optical temperature sensing technology compatible with
magneTherm system
10 mg /ml magnetite (15 nm) stabilized in DMSO subjected to 739 kHz/
9 mT - SCBG (GaAs) optical sensor
Temperature (celsius)
50
45
40
35
Normal 739 kHz - 9 mT
30
25
Pulsed 739 kHz - 9 mT
1
805
1609
2413
3217
4021
4825
5629
6433
7237
8041
8845
9649
10453
11257
12061
12865
13669
14473
15277
16081
16885
20
Period (0.02 seconds)
Figure 4: High resolution accurate real time temperature change measurement using optical
temperature sensor in a magneTherm system
Temperature Sensing for In Vivo / In Vitro Experiments
When it comes to in vivo / in vitro experiments, a more suitable remote sensing / non-invasive
option is required, primarily due to issues such as contamination of sterile bio-samples / bio-hazard
perception.
Most of all, as Magnetic Fluid Hyperthermia technology is a proposed cancer therapy technique, a
suitable sensing, recording and real time temperature monitoring technology is required in order to
measure and monitor the temperature change within the cells, tissue and/or animal as a whole, with
the above issues in mind.
The above requirements are fulfilled with the help of infrared thermography. The aggregate of
radiation emitted by a body escalates with temperature, which allows one to see differences in
temperature through an infrared thermogram. Thermal images are actual visual displays of the
quantity of infrared energy emitted, transmitted, and reflected by a body.
Compatibility with magneTherm Technology
MagneTherm technology is compatible for use with an infra-red imaging module, which allows the
user to record and measure real time temperature change for in vivo / in vitro experiments during
exposure to high frequency alternating magnetic fields.
Along with thermography, single spot and multiple spot temperature recording is also available,
facilitating the collection of multiple data points simultaneously. The other significant advantage of
these high quality thermograms derived with an infrared module is that they can be post-processed
multiple times for additional data exemplification.
Figure 5: Real time temperature change measurement using infrared thermography module
attached to a magneTherm system
The magneTherm system is tested to be compatible with all the aforementioned temperature
sensing options. As the measurement is independent of the control system, customers can utilise
existing laboratory temperature measurement systems, keeping costs affordable.
About Nanotherics Ltd
Nanotherics provide products addressing the field of magnetic nanoparticle research and
applications. In particular we aim to be the number one supplier of products for nanoparticle
heating applications utilizing AC field and solenoid coil principles.
We also apply our significant know how in magnetic nanoparticles to the field of transfection devices
and reagents for biomaterial delivery into cells for the life science research and development
market. Our aim is to provide superior performance magnetic based tools to address global markets
and to underpin the research and development of current and future nanoparticle, magnetic
particle, cancer therapy, drug delivery, genetic screening and gene therapy programs.
For more information or to request a quotation please visit www.nanotherics.com
This information has been sourced, reviewed and adapted from materials provided by nanoTherics.