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International Journal of Bioprinting Bioprinting for wearable tech and robot

of gold nanoyarn balls-coated injectable building blocks, of conductive, soft, and biocompatible electrodes. This bio-
which enhanced angiogenesis and brain function recovery mimicry may potentially reduce the foreign body response,
following traumatic brain injury. This hydrogel can be enhance signal fidelity, and ensure more stable long-term
used as bioink to fill complex defect shapes through integration with neural circuits. Adewole et al. developed
minimally invasive implantation and modulate the “living electrodes,” consisting of living cortical neurons
injury environment. Functional neuroimaging indicated and axonal tracts encased in hydrogel cylinders, for brain
restored connectivity in critical brain circuits post- activity modulation and optobiological monitoring. These
treatment with the hydrogel (Figure 4b). Fang et al. engineered constructs demonstrated rapid axonal growth
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developed a conductive multiscale-filled nerve guidance and consistent cytoarchitecture. Transplantation into the
conduit (MF-NGC) featuring a hierarchical structure of rat cortex revealed successful integration, survival, and
electrospun poly(lactide-co-caprolactone) (PCL)/collagen function, validating the approach as an effective neural
nanofibers, reduced graphene oxide/PCL microfibers, interface. These optically controllable living electrodes
and PCL microfibers. The bioprinted MF-NGCs exhibited represented critical advancements in developing novel
fine permeability, mechanical stability, and electrical optobiological interfacing tools (Figure 4d). Using
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conductivity. Within a rat sciatic nerve model, MF-NGCs conductive inks, silicone insulations, and cold-air plasma-
encouraged neovascularization, leading to significant activated electrodes, Afanasenkau et al. proposed a method
peripheral nerve regeneration and better sciatic nerve for printing biocompatible and customized electrode
function (Figure 4c). 101 arrays. These printed bioelectronic interfaces were tested
in the neuronal pathways of cats, rats, and zebrafish. The
4.2. Bioprinting of brain-machine interfaces results demonstrated prolonged integration and functional
Effective peripheral nerve regenerative techniques, stability, highlighting the ability of bioprinting for
including synthetic conduits and bioactive scaffolds, are personalized neuroprosthetic applications. 108
essential for restoring the bidirectional communication
pathways necessary for the optimal functioning of BMI. By adjusting the mechanical properties to match
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Precise transmission of motor commands and sensory those of the brain, bioprinted electrodes can record and
feedback between the brain and peripheral devices can stimulate neural activity, as well as support neural growth
be facilitated by these methods which reduce signal and healing. Liu et al. introduced a hydrogel-based elastic
latency and improve control accuracy. Innovations in microelectronics system with conductive hydrogel as the
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nerve repair that incorporate cutting-edge biomaterials conductor and an elastic fluorinated photoresist as the
and neurotrophic factors expedite axonal regrowth while passivation insulation layer. The system exhibited reduced
enhancing the long-term stability and compatibility interfacial impedance, improved current-injection density,
of neural interfaces. This symbiotic relationship and stable electrical performance under strain. It can be
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between peripheral nerve repair and BMI development used for low-voltage electrical stimulation of live mice
underscores the importance of an interdisciplinary sciatic nerve. The demonstrated properties of the soft
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paradigm that combines neurobiology, materials science, arrays provided promising applications in BMI research.
and bioengineering. Refining repair techniques enhance Additionally, the capability of bioprinting to create layered
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the reliability and durability of BMIs. Ongoing research is structures with spatial biochemical gradients offers a
crucial for advancing neural rehabilitation and human- strategic advantage in designing electrodes that can
technology innovation. Achievements in bioprinting interface with multiple types of neural cells. Roth et al.
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for nerve repair further facilitate the exploration of BMI introduced a platform called spatially patterned organoid
development. transfer (SPOT), which utilizes a hydrogel embedded
with iron-oxide nanoparticles. This setup facilitated the
A primary challenge in developing BMIs is creating precise spatial arrangement of organoids and fabricated
robust, biocompatible connections between electronic assembloids from human pluripotent stem cell-derived
interfaces and neural tissues. These connections must neural organoids. Although the correlation between BMIs
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function consistently over long periods without damaging and bioprinting is still in its experimental stage and far from
the brain’s soft tissues or causing adverse biological practical application, the combination will undoubtedly
responses. Bioprinting may address these hurdles by advance neuroscience and rehabilitation medicine.
enabling the fabrication of custom-designed tissues
with built-in electronic sensors and wiring. Moreover, 4.3. Bioprinting of neuromorphic systems
by precisely arranging different cell types and materials, While bioprinting has traditionally focused on regenerative
bioprinting can achieve the requisite sensitivity and medicine and tissue engineering, its potential for
specificity needed for effective signaling and connectivity developing neuromorphic systems introduces an exciting
in BMIs. Recently, bioprinting has enabled the fabrication interdisciplinary field. With the rapid advancement

Volume 10 Issue 6 (2024) 26 doi: 10.36922/ijb.3590