Biological Signal Monitoring
Given the popularity of electronic fitness watches
from Fitbit, Apple, Polar, and others, monitoring your heart
rate is perhaps the easiest and most popular form of
biological signal monitoring (I’m excluding non-technology
enabled forms of monitoring, such as a finger over a
pulsing artery or a hand over a warm forehead).
Whether we’re talking heart rate, blood pressure,
blood glucose level, or blood oxygenation, biological
signals share several properties: irregularity; association
with conditions; they favor specific modes of detection;
and they are accompanied by noise.
Biological signals are typically irregular in amplitude
and/or frequency, compared to the output of, say, a
The electrical signals generated by our nervous
systems, muscle activity, joint motion, and various
metabolic processes change with activity, time of day,
time since eating or drinking, food or drugs ingested,
changes in the environment, emotional state, and the like.
The nature of your heartbeat varies with your breathing,
Certain biological signals are associated with specific
physiological states or conditions. For example,
Biological signals tend to lend themselves to a
specific form of monitoring or detection. Monitoring
the electrical activity of the heart is one method of
determining heart rate, but monitoring the electrical
activity of the pancreas hasn’t proven useful in the
monitoring of diabetes.
This isn’t to say there’s only one method of
monitoring the function of a given organ.
For example, heart rate can be determined by
monitoring electrical activity of the depolarizing and
repolarizing heart tissue, or by directly (i.e.,
physically) or indirectly (i.e., optically) measuring the
pulsations of blood with each beat of the heart.
Biological signals are plagued by noise simply
because there’s a lot going on in a body. If you’re
measuring the electrical activity of a bicep muscle
via electromyography, for example, then there is
going to be unwanted signals from the triceps and
other nearby muscles, plus signals from the heart,
Build this inexpensive Arduino based heart rate
monitor that you can use as an experimental platform
to understand the basics of biological monitoring. As a
bonus, learn how to use a translational reality interface
to create an Orwellian PID controller.
with a Translational Reality Twist
26 December 2017
FIGURE 1. Hardware setup with Grove shield.