CMU Array

* Developed a 3D nanoparticle printing system to open up an entirely new design space for three-dimensional bioelectronic devices
* The printing method yields a significant cost and production time reduction
* Device design enables new experimental avenues of targeted, large-scale recording of electrical signals from a variety of biological tissues
* New multi-layer, multi material, custom 3D-printed circuit boards
* With these arrays, physiologists can optimize the microelectrode arrays (MEA) to target neural architectures ranging from dense populations in the cerebellum to multiple, layer-specific cortical ensembles – or both, simultaneously
* The construction of the customizable, acute ‘CMU Array’ microelectrodes was carried out using aerosol jet conformal printing method, which is a 3D nanoparticle printing technique
* CMU Arrays possess previously impossible electrode densities (> 6000 channels/cm2) with tip diameters as small as 10μm
* Since printing can be done on any substrate, a wide range of rigid and flexible substrates can be used for the construction of the probe
* 3D nanoparticle printing can be used to fabricate highly-customizable electrode arrays with high spatial densities
* CMU Array overcomes current limitations in large-scale recording from a variety of biological tissue and opens up several new horizons for nanofabrication of biomedical solutions
* The ability to print and route shanks at arbitrary locations allows the CMU Array to target specific regions of interest across distant areas of the brain – thus enabling precision science and reducing damage due to unwanted shanks inherent in one-size-fits-all probes
* This combination of creating 3D objects (shanks) along with layered 2D planar wires (routing) will enable a rapid on-demand fabrication of study-specific probes or patient-specific neural interfaces
* The CMU Array constitutes a new avenue of targeted, optimized research that promises to reveal information processing strategies employed by neural ensembles across brain areas
* The current method can also be combined with printing of three dimensional transparent polymers to construct optic-fiber paired probes for optogenetic stimulation and recording of neural signals
* Demonstrated a rapid 3D additive printing method to create a new class of customizable, high-density microelectrode array
* This technology paves the way to large-scale probes (thousands of channels; over several cm2 area) with easily modified probe layouts that can capture and potentially manipulate the dynamics of large, multi-area neural circuits with single-neuron and single-millisecond resolution
* Able to repeatedly penetrate brain with arrays possessing an extremely high shank density of 6400 sites/cm2 due to the method of construction and small cross-sectional area
* Represent the first ever in vivo neural recordings using a 3D printed electrode
* Lead to a more precise 3D mapping of neural circuits and precision neuroprosthetic devices
* New class of high-density neural probes to record neurological data

* Insertion of a probe into a macaque brain
* The microelectrodes can be used in non-biological applications such as changing surface hydrophobicity through texturing, increasing energy storage in batteries through an increase in the surface area, and specific sensor devices

* Recordings from mouse motor cortex were performed in separate animals using the same data acquisition system and sorting analysis. The 3D printed array had an excellent signal to noise ratio (mean 7.5, SEM 0.6), and similar neuron yield per site as that found with commercial probes

* Mice

* Probes are entirely customizable owing to the adaptive manufacturing process
* Any combination of individual shank lengths, impedances, and layouts are possible
* Because of the ease of customization afforded by computer aided design, this method of construction allows rapid changes to individual shank height and probe layout
* Arrays may be printed on a flexible Kapton® (polyimide) polymer substrate, enabling high-density, custom probes designed for use on curved or moving tissue
* Superior operation in penetrating and recording from biological tissue
* Technology increases recording sites per unit area by an order of magnitude and enables the on-demand, study-specific prototyping and manufacture of electrode configurations in a few hours
* Highly-customizable 3D printed CMU Array platform has sufficient strength and ductility to penetrate biological tissue such as brain
* Showed penetration through both mouse dura and brain, through area V2 to the hippocampus
* Owing to the small cross-sectional area and narrow tips, the 10×10 array of uniform shank length was capable of penetrating mouse brain with a basic, benchtop manual manipulator

* While extensive focus has been placed on increasing electrode channel counts, these channels are only helpful if they are able to be placed in the correct locations.

Saleh et al. 2019, The CMU Array: A 3D Nano-Printed, Fully Customizable Ultra-High-Density Microelectrode Array Platform, bioRxiv.

https://www.biorxiv.org/content/10.1101/742346v1

CMU Array: A 3D Nano-Printed, Customizable Ultra-High-Density Microelectrode Array Platform – Saleh et al., bioRxiv

https://www.biorxiv.org/content/10.1101/742346v2

Saleh et al. 2022, CMU Array: A 3D Nano-Printed, Fully Customizable High-Density Microelectrode Array Platform, Science Advances. https://www.science.org/doi/10.1126/sciadv.abj4853

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https://www.cmu.edu/ni/news/august-2019/panat-yttri-grant.html

https://www.cmu.edu/news/stories/archives/2022/october/brain-arrays.html

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