IEEE Solid-States Circuits Magazine - Spring 2023 - 25

GUEST EDITORIAL
Jan M. Rabaey and Drew A. Hall
Integrated Circuits for Biomedical Applications
B
Biomedical systems that interface
with the body and nervous system
in wearable and implantable formats
are becoming an ever more important
tool in our quest to enhance wellness
and improve health care. The global
medical electronics market was estimated
to be worth US$6.3 billion in
2021 and is expected to reach US$8.8
billion by 2026. This growth is driven
by many factors, such as an aging
population and increasing life expectancy,
adoption of IoT smart medical
devices, escalating demand for portable
medical devices, and ever more
sophistication in diagnosing and
treating diseases [1].
These medical devices have come
a long way since their early beginnings
and are evolving to become
more selective, sensitive, multimodal,
and intelligent. They must
acquire weak signals with high accuracy
under noisy and high-interference
conditions. Also, closed-loop
operation-observe, interpret, and
act-is becoming more of the essence
in advanced therapies. Even more,
devices are no longer single isolated
entities but are distributed, communicating
with each other through
wireless links. In a sense, they form
a network around and inside the
human body, complementing their
biological counterpart [2]. The challenge
for integrated circuits and SoCs
is that they must perform all of these
functions under stringent or extreme
power and size constraints. UnsurDigital
Object Identifier 10.1109/MSSC.2023.3269455
Date of current version: 22 June 2023
prisingly, publications on advancements
in integrated circuits for
biomedical applications have grown
rapidly at major solid-state circuits
conferences, such as ISSCC and the
VLSI symposium, and in the associated
journals, such as IEEE Journal
on Solid-State Circuits. However, we
believe this field is still somewhat in
its infancy, and many exciting innovations
in sensing modalities, data
acquisition, intelligent interpretation,
and active stimulation (or other forms
of interaction) can be expected over
the next decade.
In this spring edition of
IEEE Solid-State Circuits
Magazine, we present several
tutorial articles that
phrase and address some
of
the pertinent challenges
and opportunities
that face the design of
current and/or future
biomedical circuits and
systems. In the first
article, Hall, Makinwa,
and Jang [A1] describe the NEF metric
to quantify the efficiency of biomedical
front-end amplifiers that
are essential components of virtually
any recording system. The NEF
quantifies the tradeoff between
bias-current and input-referred
noise. The article further describes
several circuit techniques to improve
the NEF. The second article,
authored by Barbruni, Ghezzi, and
Carrara [A2], addresses the other
end of a closed-loop biomedical device:
stimulation. Specifically, they
discuss the many issues facing the
design of efficient and robust miniaturized
neurostimulators and
propose circuits that can lead to a
fully integrated wireless free-floating
version.
The two other articles in this
magazine examine biomedical systems-related
topics. An article authored
by Emami and Sharma [A3]
describes a radiation-free system for
in vivo, high-precision localization
of implanted miniaturized wireless
devices. In a fashion reminiscent
of magnet ic
resonant imaging,
The global medical
electronics market
was estimated to
be worth US$6.3
billion in 2021
and is expected
to reach US$8.8
billion by 2026.
the device measures the local magnitude
of an externally
generated 3D varying
magnetic field. The final
article, by Yoo [A4], discusses
means of connecting
and powering a
multitude of biomedical
devices distributed over
the human body-this relates
to the fact that meaningful
data often are only
available at one particular
place of the body and that diverse
data help to provide robustness and
accuracy. The networking approach
advocated for and demonstrated in
this article is based on the so-called
body-coupled communication mechanism
that uses the human body itself
as the transmission medium.
The four articles presented in
this issue offer only a glimpse into
the richness and diversity of the
electronic biomedical device field.
We expect many more inspiring and
innovative ideas to emerge in the coming
years, ultimately contributing
IEEE SOLID-STATE CIRCUITS MAGAZINE
SPRING 2023
25
https://orcid.org/0000-0001-6290-4855
IEEE Solid-States Circuits Magazine - Spring 2023

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