Page 91 - Handbook of Biomechatronics

86 Jeff Christenson

recognition techniques, the brain activity observed on each of the electrodes
can be correlated with intent (Tyler, 2017).
Once trained, brain arrays can be very efficient at deciphering intent and
returns much information. However, the surgery is quite invasive and the
risk of brain infection can be high. Portability of the system is generally
low due to the intensive computer processing required for the quantity
amounts of data obtained.
After about a year of Jacob’s IMES and nerve cuff system, Jacob begins
desiring even greater control and sensory feedback. After another lengthy
discussion with his medical team and with you, Jacob decides to participate
in a FDA study to use the brain array to control and receive feedback from
his prosthetic system. The surgery and recovery times are even longer, but
successful. Jacob then goes to a highly specialized lab at a top-notch univer-
sity and undergoes many days of nerve mapping and training. As the neural
map is determined, you integrate more sensors on the prostheses, develop
the control algorithms, and determine how to use the nerve outputs and
inputs available through the brain array, all in coordination with the univer-
sity lab. Finally, Jacob and the device are ready to begin moving together.

6 OTHER BIOLOGICAL SIGNAL TRANSDUCERS

Signals traveling along the motor neuron pathway are not the only
body signals for which transducers have been developed. The body is con-
stantly generating various types of signals. The following is an overview of
some of the systems developed.
Our theoretical friend Jacob first came to you to get a better device than
his passive prosthetic knee and ankle system. In this section, we will use the
sensing technology described to illustrate how to use these systems to
determine if a better system for Jacob has been developed.
6.1 Electroencephalography

Electroencephalography (EEG) was first observed in humans by Hans
Berger, a psychiatrist at the University of Jena (Fernandez et al., 2014). It
is a method of sensing brain activity, specifically the voltage variations
resulting from ionic current within the brain neurons. It is performed by
placing EEG electrodes on various standard positions around the scalp.
All the electrode signals are feed into a computer for signal analysis and
recording. Overtime, various patterns become apparent, often referred to
as waves. Four basic waves have been defined and correlated to various states