Development of Low-Cost Automatic Machine for In-House Fabrication of Custom Microwire-Based Microelectrode Arrays for Electrophysiology Recordings

Project Summary
Thanks to the affordability, ease of customization, and superior chronic recording performance, microwire-
based microelectrode array (MEA) is an important tool to record high temporal resolution neural activities to
understand the nervous system at a mechanistic level. But potential of such microwire MEA, especially large-
scale ones made with smallest wires of current scientific needs, is limited by the labor-intensive fabrication
process. If we could have the simple, mature, but tedious tasks done by an automatic machine with high
accuracy, repeatability, and throughput, it will dramatically decrease the labor cost and enable precise handling
of the smallest microwires to build complex custom configuration MEAs. Our longer-term goal is to fully
automate the fabrication and surgical implantation processes for custom minimal-damaging neural interface
implants. The near-term objective of this application is to develop a hybrid fabrication machine (less than $10k
benchtop tool), with which any neuroscience lab or department with minimal engineering expertise could build
custom linear MEAs for their specific electrophysiological recording needs with only raw material costs.
We hypothesize that, as compared to conventional manually assembled microwire MEAs, automatically
fabricated ones by violet laser-based contactless tip preparation, direct-ink-writing (DIW) based electrical
connection, image-based alignment, and machine-based manipulation will have at least equivalent chronic in-
vivo recording performance while costing fewer person-hours to make. This proposal develops and verifies
enabling technologies and the automatic machine in three Specific Aims. Aim 1 utilizes violet laser cutting for
concurrent contactless wire tip sharpening and insulation stripping. Process parameters will be optimized for
both carbon fiber and metal (tungsten) microwires to create conical sharp tip profiles and desired recording site
re-exposure area in one laser path. Aim 2 firstly investigates the printability and phase diagrams of conductive
and sealing epoxies used in our benchtop manual fabrication protocol steps. Secondly, we will develop a multi-
nozzle DIW system controlled by nozzle speed to dispense desired epoxy size/line width and a pick-and-place
unit for surface mount connectors. Such printing-assembly module makes custom MEA circuit connections.
Aim 3 focuses on integration of all module elements into a compact low-cost hybrid machine and development
of machine control algorithms and intuitive user interface. Automated motion control of all machine actuators
will be realized through cost-effective image processing algorithms using edge recognition and custom MEA
designs. All three aims will include in vivo neural signal recordings for direct performance comparison between
conventionally manual-made components/MEAs and counterparts made by developed technologies/machine.
This proposed work will deliver to the neuroscience community an automatic tool for custom microwire MEA
fabrication. It will make custom large-scale minimal-damaging microwire-based MEAs and low-cost chronic
electrophysiological recording widely available, which helps provide further insights into our nervous system.

Grant Number: 1R15NS133861-01
NIH Institute/Center: NIH
Principal Investigator: Lei Chen