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Page 12 of 21 Zhang et al. Soft Sci 2024;4:23 https://dx.doi.org/10.20517/ss.2023.58

[79]
the recording electrode . The cell experiments showed that the electrochemical performance of this
electrode was similar to that of conventional titanium NEItride electrode arrays. Furthermore, the electrode
has mechanical properties of stretchability and fatigue resistance while maintaining good electrical
conductivity. Subsequently, the team also designed an LM-based neural electrode capable of ECoG signal
acquisitions in rats [Figure 4D] . The electrode allows real-time monitoring of epileptic activity in different
[77]
seizure states and provides a new avenue for neural diagnosis and monitoring. However, it is important to
note that nanoparticles require the removal of the oxide film on their surfaces to restore their conductivities.

In 2022, our team implanted the dual-channel LM cuff electrode in rats [Figure 4E]; the electrodes can
adapt to postural changes, such as repeated stretching or twisting, and still maintain stable and effective
bidirectional transmission of high signal-to-noise ratio neural signals. The LM electrodes could also
transmit neural stimuli to peripheral nerves over a long period by triggering the cortical potentials and the
sciatic nerve signals with a clear event-related potential. Experimental results showed that the LM electrode
meets the requirements for long-term implantable peripheral nerve signal recordings and stimulations. This
suggests that the LM peripheral nerve electrode has the potential to be used as an artificial peripheral nerve
[7]
prosthesis and to repair peripheral nerve tissue in the future . In 2023, the present research team developed
an LM-based brain electrode array [Figure 4F], which exhibits excellent bending, twisting, and stretching
deformability and can form conformal contact with the skull surface of rats. The electrodes can record
electroencephalographic signals in rats at different anesthetic doses and the potentials evoked in the rat
cerebral cortex associated with auditory events (the rats were stimulated with acoustic pulses by snapping
their fingers) . Analysis of the above studies reveals that the development of recording neural interfaces
[9]
focuses on capturing neural activity with high sensitivity, spatial resolution and minimal invasiveness. High
sensitivity is often achieved by coatings, such as IrOx, PEDOT, TiNx, platinum black, etc., to reduce the
interfacial impedance. To provide high spatial resolution recording, micro or even nano level fabrication
techniques were utilized to fabricate high density neural interfaces array. For concern of minimal
invasiveness, the recording interface should be biocompatible and mechanically compliant to match the
softness of neural tissue, reducing the risk of immune responses and tissue damage from mechanical
mismatch. Therefore, low interfacial impedance is preferred when selecting conductive encapsulation
materials. Stimulation Interfaces also need biocompatibility and minimal invasiveness but with an emphasis
on delivering electrical stimuli to modulate or therapeutic purposes. For these purposes, Charge injection
capacity (CIC) is crucial for delivering sufficient charge to elicit neural response. In addition, the stability of
interface material is also very important to withstand the repeated oxidative/reductive processes and
minimize the risk of electrode degradation during the stimulation cycles. These studies demonstrate the
advantages of using LMs as neural electrode materials. In the future, LM-based neural electrodes have the
potential to become a new generation of neural interface devices to interface, supplement, and even enhance
and replace actual nerves.

LM-based neural connecting agent and functional repair
Since nerves are located throughout the body, they are very susceptible to damage in accidents (e.g., traffic
accidents, fires, etc.). However, all the instructions from the brain need to be transmitted by the nerves.
Repairing different degrees of damaged nerves is a hot topic in the clinical field. Around 2005-2007, the
present team developed a group of methods to reduce the damage to the nerves and maintain their
functions when subject to clinical surgery or accidents by controlling the ambient conditions [93,94] . The
microfluidic technology was also introduced to realize the switch on or off the entry and exit of ions, which,
in turn, affects the transmission of electrical signals . All these studies have stimulated subsequent research
[95]
trials on the neural functional connections.