<p>Implantable biomedical devices
have been widely used to treat a variety of diseases for many decades. If
allowed by the size and form factor, batteries have been the power source of
choice in implantable devices (e.g., cardiac pacemakers). Batteries are,
however, still big and come in shapes that are not ideal for minimally invasive
deployment. Inductive powering is another commonly used energy source in which
two well-aligned coils allow a transmitter to power the implanted receiver
(e.g., cochlear implants). Once the receiver coil becomes small (mm-scale), the
inductive powering link becomes very inefficient and sensitive to slight
misalignment between the coils. Hence, it becomes increasingly difficult to
power small devices implanted deep (>5 cm) within the tissue using inductive
powering. Ultrasonic powering is an attractive alternative for powering
miniature devices since it can penetrate deep into the tissue, it has greater
efficiency at mm-scale receiver size, it can be omni-directional, and it is
more amenable to miniaturization.</p>
<p>In this dissertation, I describe
the use of ultrasonic waves to power and control mm-scale implantable devices.
After a detailed look at ultrasonic transmission link, I will discuss factors
affecting the power transfer efficiency. These include the effect of receiver
aspect ratio and size on the resonant frequency and factors related to acoustic
and electrical matching. A 3D printed acoustic matching layer in then described.
I will discuss two applications using ultrasound to power and control
implantable devices. The first is a low-power on-off acoustic control scheme to
reduce the standby power consumption in implantable devices. The second is an
ultrasonically powered electrolytic ablator with an on-board micro-light-source
for the treatment of cancer.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/7779509 |
| Date | 10 June 2019 |
| Creators | Jiawei Zhou (5930498) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Ultrasonically_Controlled_Powered_Implantable_Medical_Devices/7779509 |
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