Page 43 - EE Times Europe Magazine | February 2020

EE|Times EUROPE — Boards & Solutions Insert

BIOELECTRONICS
Ultra-Low–Power Bionic

Chip Promises Alzheimer’s

Treatment

By Maurizio Di Paolo Emilio

he path to a long-sought treatment for one of the most dreaded diseases could lead
through some very small circuits. An international research team led by scientists from
the University of Bath in the United Kingdom has created artificial neurons in the lab
T that demonstrate the possibility of making bionic chips that can reproduce the electrical
response of biological nerve cells, with an eye toward repairing damaged nerve circuits and
restoring function to patients. Scientists hope to use bionic chips to treat both cardiac and neuro-
degenerative disorders, including Alzheimer’s and Parkinson’s.
Alzheimer’s disease involves the progressive death of neurons, with cognitive, behavioral,
and motor consequences; it is a bit like taking away the soul of the person affected. According
to a 2016 study by Trust Source, every 66 seconds, a new Alzheimer’s case occurs in the United
States alone; in total, about 5.4 million adults in that country are living with the condition.
Currently, there is no cure, though there are clinical treatments that can delay progression of
the disease and extend the amount of time that individuals are able to carry out daily activities.
Now, researchers are exploring nanotechnology solutions that might help improve the quality
of life of those afflicted.

UNDERSTANDING INTRACELLULAR DYNAMICS
The electrical properties of biological cells have long been studied to understand intracellular
dynamics. The difficulty of measuring microscopic parameters that control the dynamics of ionic
currents and the nonlinearity of ionic conductance have so far hindered efforts to construct
quantitative computational models and create neuromorphic devices able to replicate the exact
response of a biological neuron.
The growing attention paid to implantable bioelectronics for the treatment of chronic dis-
eases is driving technology toward low-power solid-state analog devices that accurately mimic
biological circuits. Analog asynchronous electronics are the most promising way to integrate

Figure 1: Biomimetic solid-state ion channel. (a) The conductance of ion species α is
modulated by an activation gate and an inactivation gate. The net ionic current, I α, is
the difference between the activation current (I ) and the inactivation current (I ).
m
h
The Heaviside function, θ speci es that the current mirror outputs a positive current α
when I m > I h and 0 otherwise. (b) Electrical equivalent circuit of the neuron membrane.
(c–g) Block diagrams of subcircuits for (c) the gate recovery time, (d) current mirror, (e)
current multiplication ( ) transconductance ampli cation and (g) sigmoidal activation
inactivation. (Image: Nature Communications)

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