Northwestern Prints Neurons That Signal Living Brain Cells

Northwestern University researchers have built electronic neurons using aerosol jet printing that successfully send and receive electrical signals with living brain cells — establishing two-way communication between a printed structure and biological tissue.

Context

Brain-machine interfaces have historically required invasive implants manufactured through rigid silicon fabrication — expensive, brittle, and mechanically mismatched to the soft, constantly-moving tissue they’re designed to interface with. The brain shifts slightly with every heartbeat and breath; rigid implants cause cumulative tissue damage over time. Neuromorphic computing faces a different version of the same constraint: biological brains operate approximately five orders of magnitude more efficiently than digital computers, but replicating the brain’s architecture in hardware has required specialized fabrication techniques that don’t scale to manufacturable devices.

Aerosol jet printing — a commercially available additive manufacturing process — changes both equations if it can deposit electronically active materials with sufficient precision and biocompatibility. The question the Northwestern team, led by materials scientist Mark Hersam, has now answered affirmatively: it can.

The Detail

The research, published in Nature Nanotechnology under the title “Printed MoS₂ memristive nanosheet networks for spiking neurons with multi-order complexity,” used electronic inks based on molybdenum disulfide (MoS₂) and graphene deposited onto flexible polymer substrates. The resulting structures are memristive spiking neurons — electronic systems that replicate the signal-firing behavior of biological neurons, including the ability to modulate signal strength based on prior activity. This adaptive behavior is what makes them functionally distinct from simple electrical conductors; they behave more like synapses than wires.

When placed adjacent to living mouse brain cells maintained in laboratory conditions, the printed neurons initiated electrical communication: signals from the printed structures triggered measurable responses in the biological cells, and the biological cells’ responses were detectable by the printed system. Two-way communication between an engineered electronic structure and biological tissue is the threshold capability that separates a neural interface from a neural monitor.

The flexible polymer substrate is a critical enabler that distinguishes this approach from prior silicon-based work. Mechanical compliance with biological tissue is the unsolved problem in long-term implantable devices — a substrate that moves with the brain rather than against it avoids the inflammatory response that currently limits implant lifespans. Both MoS₂ and graphene are biocompatible at the relevant scales, and aerosol jet printing is an existing manufacturing process with established industrial applications.

The Pattern

The Stack Archive has tracked a consistent trajectory in 3D printing research over the past 60 days: the technology advancing from production-floor manufacturing into biological and molecular-scale applications. The bioprinting organs reality check mapped where tissue printing currently stands against clinical timelines. The Rice University microwave printing work established sub-millimeter electronics fabrication outside the cleanroom. Northwestern’s printed neurons add a third data point: 3D-printable structures that interface directly with biological neural tissue, using commercially available processes and materials.

Source: 3DPrint.com

Content created with AI assistance and reviewed for accuracy.