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54 EE|Times EUROPE — Sensors Insert

Neuromorphic Chips Mimic the Human Brain

reported in the literature are associated with specific ion channels.”
Indiveri said, “Another application area in this domain that is more
mature is cochlear implants. The main advantages of neuromorphic
chips are their lower power consumption, their compactness, and their
potential for ‘speaking the same language’ [as the] spiking neurons
they are being interfaced to, i.e., that of action potentials and neural
dynamics.”
Neuromorphic chips could also be used to listen to motor neuron
activity and to decode the expected muscle-activation pattern (e.g., for
control of a prosthetic device).
The chips are analog devices, typical of nonlinear dynamic systems.
This means they read raw nerve signals and output neuron oscillations
as analog voltages. “No ADC/DAC is needed,” said Nogaret. “Asynchro-
nous chips can thus integrate complex, noisy synaptic inputs in real
time. The main difficulty lies in conditioning the chip — through its
parameters, gate biases, etc. — to respond identically to a specific type
of biological neuron. This is the purpose of the parameter estimation
methods that our lab and others are beginning to develop.”
The chip must be minimally invasive in terms of biocompatibility,
adapting to signals with virtually zero power consumption by maxi-
mizing the use of energy-harvesting sources. The design constraints
are the same as those imposed on the electronic circuits and systems
currently being used in implants such as cardiac pacemakers. “To a Figure 2: The Paradromics system (Image: Paradromics)
large extent, these conditions are already accessible, thanks to the
60-or-so years’ experience we have in producing VLSI circuits,” said
Nogaret. “The challenge of optimizing these chips further to optimize Further research and development are required before complete
bioimplants will be met through incremental engineering progress and adoption is possible, however.
feedback from targeted trials.” Among the companies working on application cases, Ceryx Med-
VLSI circuits realized with CMOS technology are a strategic tech- ical is developing biolectronic central pattern generators (CPGs) to
nology for the development of digital systems; continual increases imitate the body’s nerve centers. CPGs produce rhythmic outputs in the
in microelectronics integration have enabled systems of rising absence of rhythmic inputs. In medical applications, the devices could
complexity. help control involuntary and voluntary rhythmic processes such as
The development of VLSI systems has resulted in highly specialized peristalsis, heart rate, and even gait, restoring proper functioning when
technologies. Integration at the packet and chip level is more practical natural rhythmic processes have been impaired by disease or injury.
for the implementation of VLSI systems because of their compact size Startups Neuralink and Paradromics are also working to optimize
and short signal interconnection. The growing complexity of chips neuromorphic solutions. Neuralink is building an implantable wireless
creates a need for improved design methodologies and more powerful system that has far more electrodes so that it can record signals from
CAD environments. more neurons (Figure 1).
Paradromics is bringing to market the first high-data-rate brain
computer interface (Figure 2). The implantable system can be used
for practical health-care applications by vastly increasing data rate,
portability, and durability. The startup is focused on enabling an even
higher density of probes over the face of its neural implant by integrat-
ing more, smaller electrodes.
Future challenges for neuromorphic devices are to increase the
efficiency of the response and the improvement of the model through
deep-learning tools, with the aim of transforming the brain into an
increasingly digital one. The key application for such solutions is a
digital cure for Alzheimer’s disease and other cognitive disorders.
A neuromorphic chip can mimic the brain to process data effectively,
far surpassing existing machines, which struggle to accommodate the
demands of big data, AI, and machine learning. Neuromorphic chip
processing is also expected to play a crucial role in non-medical areas,
including voice/face recognition and data mining, learning accurately
from evolving data. ■
REFERENCE
1 E.L. O’Callaghan, R.M. Lataro, E.L. Roloff, A.S. Chauhan, H.C. Salgado, E. Duncan,
A. Nogaret, and J.F.R. Paton. Enhancing Respiratory Sinus Arrhythmia Increases
Cardiac Output in Rats with Left Ventricular Dysfuntion. The Journal of Physiol-
ogy, February 2020 598(3):455–471.
Figure 1: This sewing-machine–like robot inserts electrodes into Maurizio Di Paolo Emilio is a staff correspondent at AspenCore,
the brain. (Image: Neuralink) editor of Power Electronics News, and editor-in-chief of EEWeb.

JUNE 2020 | www.eetimes.eu