IEEE Solid-States Circuits Magazine - Fall 2022 - 49

water soluble, and no other adhesive is
needed. To accommodate the custom
communication protocol, a compact
external RX hub was also developed,
which consisted of an antenna, an SDR,
and a computer, which can be as small
as a card-sized Raspberry Pi.
Two EEG experiments are conducted
to compare the penny-sized
device with a clinical instrument. The
first experiment is the alpha-wave
test (eye open/close), which is an EEG
signal that can be measured when a
person is awake with the eyes closed.
The results are usually analyzed in
the frequency domain, shown in Figure
14(a), and we can see that the
result from the penny-sized recorder
agrees well with the clinical system.
The second experiment is the ERP,
as shown in Figure 14(b), which can be
used in understanding mental health
conditions. Colored shapes are periodically
shown on the screen. Most of
them have the same color, which is red
here. However, one with a different
color occasionally shows up. The ERP
in this test is the EEG signal around
300 ms after this " odd " -colored item is
presented. As can be seen here, the
results from both setups match well.
These two experiments validate the
device in capturing clinically important
EEG signals. With the integrated FDMA
TX validated in Figure 11, this device
is a promising candidate to achieve
distributed wireless EEG recording.
Conclusions
Noninvasive EEG recording has the
potential to benefit everyone in mental
health monitoring and more undiscovered
applications. A wearable EEG
recorder is in demand for long-term
recording and BCI functionalities
with the following properties:
■ a similar recording accuracy and
site coverage as the clinical
instruments
■
easy-to-prepare electrodes
■ minimal discomfort with no loose
or long wires
■ a long-term battery life
■ compact and mobile external RX.
Thanks to a better understanding
of EEG signal characteristics and
recording requirements,
recent
wearable prototypes have already
validated the possibility of a distributed
wireless recording scheme with
no long wires. Further improvements
in circuit and system optimization
have the potential to enable EEG as a
prevalent health-monitoring method
in the near future.
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IEEE SOLID-STATE CIRCUITS MAGAZINE
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IEEE Solid-States Circuits Magazine - Fall 2022

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