applied on the membrane sandwiched between two sections filled with electrolytes. This

acts as the driving force to pass charged biomolecules via a nanopore, and provides

controls of ionic current across nanopores. This way, information about the structure and

motion of biomolecules could be determined. The nanopore-based bioelectronics is highly

suitable for DNA sequencing due to its label-free and high efficiency for the analysis of

single molecules. In other words, the variation in ion current depends on the nucleotide

or base type passing through the nanopore. Accordingly, measuring variation in ionic

current enables the estimation of the base sequence in a DNA molecule. The nanopore-

based bioelectronics can be modified through the attachment of optical or electrical

readout techniques. For DNA sequencing, graphene emerged as a promising candidate

due to its thickness lies in between the spacing (0.32–0.52 nm) of nucleotide. However,

cracks and defects in the graphene membrane could result in poor insulation and higher

disturbance in ionic current. Beyond graphene, MoS2, BN, and other heterogeneous-

layered 2D materials are also studied for nanopore sensing.

3.4.3 Mechanism for Multi-Electrode Array-Based Bioelectronics

The multi-electrode arrays (MEAs) technology is extensively used in neuroscience to si­

multaneously record intra- or extracellular of a variety of neurons [52]. The action po­

tential of a cell that controls the electrical behavior of neuro or cardio cells is recorded

through electrodes. This action potential travels via a neuron’s axon from a membrane

region to a neighboring active area and the inactive membrane potential towards a barrier

for activation. To estimate neural signals effectively, the velocity of conduction plays a

vital role. The conduction velocity is directly proportional to the axoplasm resistivity and

the membrane capacitance. The extracellular signals produced by cells are detected when

MEAs electrodes are placed over the cell. The MEAs enable to map of the neuronal

network as the function of physiological and pathological. To date, ~10,000 electrodes are

placed in an MEA chip for in-vitro recordings, while only ~100 electrodes for in-vivo

recordings [53]. In addition, the extracellular signals are several times smaller than in­

tracellular signals, making it challenging to record them with less noise.

3.4.4 Mechanism for Optical Resonator-Integrated Bioelectronics

To sense the interactions of biomolecules, graphene integrated with surface plasmon

resonance (SPR) based biosensor is employed. In this sensor, the detection of biomole­

cular interactions is accomplished via a subsequent change in the refractive index near

the detection surface [54]. This variation alters the resonance wavelength. A shift in re­

sonance is optically determined through the attenuated total reflection (ATR) method.

Graphene enhances the efficiency of the SPR sensor by increasing biomolecule adsorption

on the graphene surface. When the micro/nanoribbons or patterned graphenes are in­

tegrated with a SPR sensor, then unusual electrical and optical properties are observed.

The features of resonant absorption and tunability of properties via electrostatic gating of

patterned graphenes have brought new research avenues to develop bioelectronic devices

with high sensitivity and label-free detection.

3.4.5 Mechanism for Multifunctional Sensor Array-Based Bioelectronics

A multipurpose sensing/stimulating system is newly examined as an alternative to a single

functional component system [55]. In the area of cardiology and neuroscience, simultaneous

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Bioelectronics