IEEE Signal Processing - May 2018 - 112

Figure 3. A convenient placement of electrodes on the forearms, for the recording of the ECG.

cumbersome setup procedures as it only
requires a minimum of two electrodes to
be placed on symmetric positions on a
person's body with a third, ground elec-
trode, located next to one of the sensing
electrodes. For a good tradeoff between
the ease of setup and strength of signal
obtained, we instructed the students
to place the electrodes on their forearms
(see Figure 3).

Signal acquisition device: The iAmp
Figure 4. Our iAmp recording device against
one U.K. pound coin (22.5 mm in diameter).

The key recording component that was
instrumental to the success of this

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Experimental setup

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Figure 5. Cardiac potentials on the body surface at the approximate timing of an R-peak in the ECG
cycle. (Figure produced with COMSOL Multiphysics software.)
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IEEE Signal Processing Magazine

assignment was our own custom-made
portable signal acquisition device,
referred to as the iAmp (see Figure 4).
The iAmp is equipped with a 24-bit ana-
log-to-digital converter (ADC) with a
sampling frequency of up to 32 kHz
( fs = 1 kHz was used for our record-
ings), a microprocessor, and a secure dig-
ital (SD) card slot to store the data. While
the iAmp is designed to record any bio-
potentials (e.g., ECG, electroencephalo-
gram, and electromyogram) from up to
eight channels, in our experiment, it was
only used to record the ECG.
The distinguishing features of the
iAmp that contributed to its deployment
in our assignments are its portability,
"hackability," and the simple input-out-
put (I/O) interface. For example, the set-
tings for the iAmp can be changed by
the students, as the configuration file is
stored on its SD card memory. Further-
more, without the iAmp, it would not be
economically feasible for us to design
this coursework, as commercially avail-
able biopotential recording devices are
cost-prohibitive for educational applica-
tions. For example, based on our market
analysis, 15 commercially available ECG
recording devices (the number of iAmps
used in our course) would have cost the
university approximately US$60,000.
(This information is based on the Avatar
ECG recorder, which costs approximate-
ly US$4,000 per device; see www.egi
.com/research-division/research-division-
research-products/avatar for more infor-
mation.) With our own in-house built
iAmp, on the other hand, we were able to
give the students a hands-on experience
of the state of the art in wearable vital
signs monitoring devices at a fraction of
this price, and in a natural way.

May 2018

Before the start of the experiments, the
students are briefed on the principles of
cardiac electric potentials and about any
potential health hazard or discomfort.
Building upon their engineering back-
ground, they are taught how cardiac
electric potentials are generated by cur-
rents in the heart muscle and how
potential differences between two points
on the body surface are measured
(see Figure 5).

http://www.egi.com/research-division/research-divisionresearch-products/avatar http://www.egi.com/research-division/research-divisionresearch-products/avatar http://www.egi.com/research-division/research-divisionresearch-products/avatar

Table of Contents for the Digital Edition of IEEE Signal Processing - May 2018