Medical Design Briefs - January 2023 - 29

n From Theory to Prototype
In experiments, the scientists created
a fully implantable neural interface using
ionic communication for rats. They
showed it could acquire and noninvasively
transmit brain data from freely
moving rodents over the span of weeks
with enough stability to isolate signals
from individual neurons.
Using 10 communications lines with
currently available commercial electronics,
the scientists achieved communications
rates of 60 MHz. They estimated
that a single ionic communications line
could potentially achieve communication
rates of up to 14 MHz.
The scientists note that ionic communication
required low voltages and substantially
less power than radio or ultrasound
communications. Their experiments also
revealed their ionic communication device
proved thousands to millions of times
more energy-efficient at communicating
data than other approaches used with implantable
bioelectronics.
Ionic communications devices can be
made from materials that are soft, flexible,
commercially available, biocompatible
- that is, not harmful to living tissues
- and even biodegradable, suggesting
that they could readily find use in practical
implantable devices that can dissolve
away once they are no longer needed.
Khodagholy and his colleagues now aim
to combine ionic communication with
organic transistors in an implantable
bio sensor.
n A United Theme
This latest work continues Khodagholy's
overall research seeking to connect
bioelectronic devices with the human
brain. For example, he and his colleagues
recently developed a material that helps
ionic signals conduct only in specific chosen
directions. This can help scientists
develop circuitry that uses ions instead of
electrons in order to better interface with
the body. Such circuits would ordinarily
not work if ions could travel in all directions
and cause unwanted interference
between different parts of each circuit.
The new " anisotropic ion conductor " is a
soft, biocompatible composite material,
suggesting it could prove useful in implantable
bioelectronics, and the processes
to synthesize it are straightforward and
scalable. Their study, " Anisotropic Ion
Conducting Particulate Composites for
Bioelectronics, " appeared in the journal
Advanced Science.
" The novel material we developed has
unique properties that enable the implementation
of large-scale organic bioelectronic
devices, which can enhance their
translation
tions, " Khodagholy says. " Next, we aim to
design compact and complex anisotropicion-conductor-based
integrated circuits
composed of many organic transistors
for bioelectronics applications. "
For more information,
visit www.
engineering.columbia.edu. Contact: Dion
Khodagholy, Department of Electrical
Engineering, dk2955@columbia.edu.
Designing Feature-Rich Wearable Health and
Fitness Devices
Solid-state lithium
rechargeable microbattery
technology enables
smaller, better-fitting
devices.
Ensurge Micropower
San Jose, CA
Wearable devices are transforming everything
from remote patient monitoring to
fitness tracking and hearing assistance. The
next step is to shrink the size of these devices
while offering more comfortable shapes
and additional features and wireless communications
capabilities. The biggest obstacle
is the battery, and more specifically
the lithium-ion (Li-ion) batteries used in
the majority of wearables. Today's devices
have been tethered to the form-factor and
performance limitations imposed by these
batteries' liquid electrolyte chemistry.
An alternative has now emerged. Solidstate
rechargeable lithium microbatteries
that range from 1 to 100 mAh use an inherently
safer solid electrolyte than Liion.
They increase energy density in a
Medical Design Briefs, January 2023
to human health applicaWearable
devices, such as continuous glucose monitors are transforming patient care. (Credit: Ensurge
Micropower)
smaller, rectangular cuboid (rather than
cylindrical) form factor whose length,
width and height can be customized
based on the needs of the wearable application.
They also can be assembled onto a
www.medicaldesignbriefs.com
printed circuit board (PCB) using the
same standard assembly processes as a
wearable's other components, dramatically
simplifying how wearables can be
designed and manufactured.
29

http://www.engineering.columbia.edu http://www.medicaldesignbriefs.com

Medical Design Briefs - January 2023

Table of Contents for the Digital Edition of Medical Design Briefs - January 2023