<p>Measurement of physiological deformations in specific
tissues can provide significant information for the diagnosis, monitoring, and
treatment of medical conditions. Yet these deformation measurements can be hard
to obtain, especially when the targeted tissue is inside the body where optical
access is denied. Current medical imaging technologies, including ultrasound,
magnetic resonance imaging (MRI) and X-ray, can image soft tissues and bones
with decent spatial resolution. However, they are not feasible for chronic
tissue monitoring or cases in which rapid tissue deformation/vibration
measurements are required. Wireless magnetic sensing is a favorable option for
implantable pressure, strain, or deformation sensing systems due to its compact
size, passiveness, high sampling rate and minimal interference from biological
materials. Polymeric magnets, made from polymer carrier and embedded magnetic
micro/nano-particles, possess the traits of flexibility, stretchability and
biocompatibility that are preferred for biomedical applications. Nonetheless,
their magnetic field is much weaker comparing to that of traditional
ferrous/rare earth magnets. Emergence of highly sensitive magnetic sensors
based on various principles (Hall effect, anisotropic magneto-resistance (AMR),
giant magneto-resistance (GMR), giant magneto-impedance (GMI), tunneling
magneto-resistance (TMR)) has enabled precise magnetic sensing of such
polymeric magnets. To this end, we developed wireless magnetic sensing systems
capable of measuring tissue deformations through implantable polymeric magnets
for biomedical applications. This thesis work details the end-to-end
development (magnetic sensor selection, magnetic transducer design &
fabrication, measurement algorithm development) and the collaborative,
interdisciplinary experiment result of a wireless brain deformation sensing
system for blast induced traumatic brain injury (bTBI) featuring a polymeric
magnetic disk, and a wireless strain sensing system for bladder dysfunction or
heart failure (HF) featuring a stretchable polymeric magnetic band. Both
systems comprise of one or more polymeric magnetic transducers, an external
magnetic sensor / sensor array, and a signal processing unit. Upon tissue
deformation, the magnetic transducers attached to the tissue deform jointly,
inducing a change in the magnetic field that can be measured wirelessly by the external
magnetic sensor / sensor array. Tissue deformation is then recovered from the
measured magnetic field signal via the signal processing unit.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/13110857 |
| Date | 16 December 2020 |
| Creators | Tianshuo Zhang (5930477) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Wireless_Sensing_of_Tissue_Deformations_Featuring_Polymeric_Magnets/13110857 |
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