manufactured materials. These devices include from electrocardiographs, cardiac pace­

makers, defibrillators, blood pressure, and flow monitors to medical imaging systems.

Some examples of new materials used in medicine are a polydimethylsiloxane microchip

attached to a flexible printed board [27]; a 3D polydimethylsiloxane flexible matrix with a

Ti layer deposited using radio-frequency-biased plasma [28]; a glass-based 96-well mi­

croelectrode array with microtiter plates supported on polymethylmethacrylate [29]; and

a bioinorganic nanocomposite used for monitoring of cell redox-state formulated with

DNA-MoS2 and natural peptides [30]; all these devices seek the advance of the medicine

and biology to understand, monitor, and control living systems.

2.3.1.1 Materials for Electroactive Scaffolding

Approaching the science of integral bioelectronics systems from a biomaterial scaffolds

point of view is fundamental to reaching suitable tissue-electrode assemblages. A chal­

lenge of bioelectronics consists in the development of scaffolds able to mimic the native

cell functions. Particularly for those types of cells that form part of sensible tissues, be­

cause in the case of damage they would be tuned or modulated by electrical stimulus; for

example, in neural or muscular systems. Neurons, in this case, are sensitive to electrical

stimulus, causing contraction and relaxation that, in case of damage, scaffolds are ideal to

help in the restoration of tissue activity.

Tissue engineering is under continuous exploration in the matter of scaffolds; the foun­

dation is to achieve a controlled electrical input for an action or response. The study of 3D

scaffolds in cells is a more realistic point of view because the additional dimension provides

results close to those observed in human organs. 3D scaffolds have the objective of being

seeded with cell cultures to promote the growth of new cells and subsequently new healthy

tissue. But as in anything related to bioelectronics, issues always arise, mainly those re­

specting differentiation, modulation of cell growth, and acceptance (hypoallergenic).

Currently, most projects aim to develop 3D scaffolds in an attempt to emulate biological

systems accurately. It is affordable to think that if the goal to achieve precise and well-

structured scaffolds is complete, then another door of biotechnology would be unlocked

[31]. For that reason, it is important to mention those promissory bioelectronics materials

that comply with the basic requirements for 2D and 3D scaffolds such as a copolymer

formed only by synthetic polymers, poly(ethylene glycol), and diacrylate-poly(acrylic acid)

[32]; a copolymer using the absorbable poly-l-lactide modified with synthetic nanoparticles

of polypyrrole [33]; a copolymer of biodegradable polycaprolactone modified with poly­

aniline [34]; a thermo responsiveness composite of the copolymer [poly(polyethylene glycol

citrate-N-isopropylacrylamide)] modified with graphene oxide [35]; and a composite of

exfoliated graphene and polyacrylamide [36].

2.3.1.2 Materials for Photostimulation

Organic and inorganic materials can induce photostimulation. This phenomenon may be

exploited as an alternative for bioelectronics applications. New semiconductor and con­

ductor materials are studied for their implementation in bioelectronics as components of

pacemakers and other optoelectronic and mechanical therapies through optical stimulation.

This promising method seizes the lights to the research about photons able to excite ion and

molecular receptors to modulate, for example, cardiac cell disorders. Even if photo­

stimulation is effective and noninvasive, the photostimulation yet faces some difficulties

doing its clinic implementation is not completely viable, and it requires perfection to adapt

Materials and Their Classifications

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