A workforce of researchers has created neurological probes utilizing a Japanese paper-cutting artwork type referred to as Kirigama, trying to match the mind’s complexity by having a number of electrodes that cowl all three dimensions in a single system.
The will to know the complexity of the human mind has led to neuroscience changing into one of many fastest-growing fields of science. Maybe unsurprisingly, mapping the complicated construction of our brains and the neurological operate of assorted areas, and figuring out points with this functioning, is a fancy and difficult process.
This process is more and more being tackled utilizing neuroelectronic interfaces comprising microelectrode arrays (MEAs). MEAs might be employed in research of cultured neurons outdoors the mind, or “in vitro,” and in residing organisms, “in vivo.” These implants can thus serve each as a bridge between the nervous system and exterior digital methods, facilitating the recording and stimulation of neural exercise. 3D MEAs will also be used as brain-machine interfaces, not solely studying mind indicators but additionally sending indicators again, serving to higher perceive how the mind works, research neural problems, and even develop therapies based mostly on electrical stimulation.
Kirigama transforms a flat sheet of paper right into a three-dimensional design, usually with an intricate and elaborate construction, via reducing and folding. The creation of the Kirigama-inspired platform is detailed in a paper revealed within the journal TBA.
“Attributable to its 3D design, our system combines the options of two applied sciences into one. It could possibly file mind indicators each from the floor and from deeper layers of mind tissue,” mentioned workforce member Viviana Rincón Montes of the Forschungszentrum Jülich.
Mapping the complexity of the mind
Crew member and Forschungszentrum Jülich researcher Marie Jung added that the kirigami shanks that comprise the electrodes are very small — simply 50 micrometers (µm) extensive. For context, a human hair is on common round 75 µm.
“Our mildew design permits us to fold and form the versatile probe manually beneath a microscope,” Jung mentioned. “It’s like a key lock, the place the elements match collectively completely. Each time I fold a kirigami probe, I’m amazed at how easy and quick our methodology is!”
Jung added that, not like another kirigami strategies, the workforce’s method doesn’t use hazardous or harsh manufacturing processes. As an alternative, the researchers utilized a mechanical forming course of that sandwiched a flat 2D design between two matching molds, then utilized stress and warmth. This reworked an ultrathin, versatile sheet, thinner than paper and versatile as plastic wrap (cling movie), into a completely 3D construction on the micrometer scale.
“This course of permits all of the shanks, which comprise the electrodes, to fold into an upright place on the identical time,” Jung mentioned. “This enables us to fold as much as 128 shanks on the identical time — quick and reliably!”
Testing a kirigami-based neurological probe
The workforce examined their 3D MEA in a number of steps, starting within the lab with in vitro fashions earlier than transferring on to in vivo testing.
“First, we examined the 3D MEAs in managed laboratory circumstances. This included testing the mechanical properties of the supplies, evaluating the reliability of the folding course of utilizing optical inspection, and confirming the units’ performance via electrochemical checks,” mentioned Rincón Montes. “We additionally examined whether or not the units can be inserted into brain-like supplies to evaluate their suitability to be used in neural tissue and performed checks beneath accelerated getting old to see how lengthy they may survive beneath physique circumstances.”
The researchers additionally examined whether or not the units may very well be inserted into brain-like supplies, assessing their suitability to be used in neural tissue, and performed checks beneath accelerated getting old to see how lengthy they may survive beneath physique circumstances.
“Subsequent, we moved on to actual organic samples, together with human mind slice cultures ready from cortical tissue donated by sufferers who had epilepsy surgical procedure and the cortex of residing rodents,” Rincón Montes added. “In these checks, we utilized various kinds of stimulation to file numerous forms of neural indicators. For the human mind slices, we modified the chemical make-up of the encircling fluid to set off epileptic-like exercise. In rodents, we utilized each contact and visible stimuli.
“These experiments allowed us to file a variety of mind indicators — from single neurons to teams of neurons- and observe how responses modified throughout totally different mind layers.”
The workforce discovered that by way of manufacturing, their methodology has a 98% success fee after folding and an 80% success fee after the ultimate post-processing steps, comparable to including an electrode coating and packaging. Although the folding course of is at present carried out manually by aligning the 2D sheet and urgent by hand, they anticipate this success fee to enhance with automation and when using strategies like pick-and-place methods or micromanipulators.
“One of the crucial stunning issues we found was how nicely a method usually used for shaping supplies on a big scale works on the micro-scale,” Vivana Rincón Montes mentioned. “Our designs provide stability throughout manufacturing, permitting us to implement them manually with no need complicated setups. Furthermore, the robustness of our units has been confirmed to resist each mechanical stresses throughout insertion and organic stresses (e.g., immune responses). In actual fact, after being implanted for a month, our units saved their 3D form when explanted!”
The workforce is at present engaged on a number of methods to enhance their 3D MEA units by refining their course of and designs to achieve deeper layers of the mind with a single insertion whereas avoiding blood vessels, thus making the insertion safer. The workforce can also be engaged on the steadiness of the electrode coating of their units by optimizing the formulation and coating strategies for conductive polymers mixed with noble metals comparable to iridium oxide.
“At present, we are able to create a tool with as much as 128 shanks, every containing 4 electrodes, for a complete of 512 electrodes,” Rincón Montes mentioned. “Nevertheless, we are able to solely join as much as 32 electrodes or 64 if we use massive, cumbersome connectors. That’s why we’re additionally engaged on new methods to attach all of the electrodes to exterior electronics with out making the system too massive or heavy.”
Rincón Montes added that it might nonetheless be a while earlier than 3D MEAs like these of the workforce are employed in real-world healthcare.
“We have to ensure that the units are dependable and secure for long-term use, and extra analysis is required to completely perceive how they will help restore misplaced neural capabilities,” Rincón Montes concluded. “We’re at present specializing in utilizing this know-how in visible prosthetics. Because of the massive variety of electrodes, it could help two-way communication — in different phrases, we are able to each learn and ship neural indicators, both within the mind or the retina.
“This might open the door to new methods of restoring imaginative and prescient in people who find themselves blind.”
Reference: V. Rincón Montes., M.Jung., J. Abu Shihada., et al., Flexible 3D kirigami probes for in vitro and in vivo neural applications, (2025). DOI: 10.1101/2024.11.05.622167
