Scalable, Modular Three-Dimensional Silicon Microelectrode Assembly via Electroless Plating.

We devised a scalable, modular strategy for microfabricated 3-D neural probe synthesis. We constructed a 3-D probe out of individual 2-D components (arrays of shanks bearing close-packed electrodes) using mechanical self-locking and self-aligning techniques, followed by electroless nickel plating to establish electrical contact between the individual parts. We detail the fabrication and assembly process and demonstrate different 3-D probe designs bearing thousands of electrode sites.

Heterogeneous neural amplifier integration for scalable extracellular microelectrodes.

We here demonstrate multi-chip heterogeneous integration of microfabricated extracellular recording electrodes with neural amplifiers, highlighting a path to scaling electrode channel counts without the need for more complex monolithic integration. We characterize the noise and impedance performance of the heterogeneously integrated neural recording electrodes, and analyze the design parameters that enable the low-voltage neural input signals to co-exist with the high-frequency and high-voltage digital outputs on the same silicon substrate. This heterogeneous integration approach can enable future scaling efforts for microfabricated neural probes, and provides a design path for modular, fast, and independent scaling innovations in recording electrodes and neural amplifiers.

Close-Packed Silicon Microelectrodes for Scalable Spatially Oversampled Neural Recording.

Objective: Neural recording electrodes are important tools for understanding neural codes and brain dynamics. Neural electrodes that are closely packed, such as in tetrodes, enable spatial oversampling of neural activity, which facilitates data analysis. Here we present the design and implementation of close-packed silicon microelectrodes to enable spatially oversampled recording of neural activity in a scalable fashion.

Three-dimensional multiwaveguide probe array for light delivery to distributed brain circuits.

To deliver light to the brain for neuroscientific and neuroengineering applications like optogenetics, in which light is used to activate or silence neurons expressing specific photosensitive proteins, optical fibers are commonly used. However, an optical fiber is limited to delivering light to a single target within the 3D structure of the brain. Here, we describe the design and fabrication of an array of thin microwaveguides, which terminates at a three-dimensionally distributed set of points, appropriate for delivering light to targets distributed in a 3D pattern throughout the brain.

Towards optogenetic sensory replacement.

Over the last several years we have developed a rapidly-expanding suite of genetically-encoded reagents (e.g., ChR2, Halo, Arch, Mac, and others) that, when expressed in specific neuron types in the nervous system, enable their activities to be powerfully and precisely activated and silenced in response to light.

Multiwaveguide implantable probe for light delivery to sets of distributed brain targets.

Optical fibers are commonly inserted into living tissues such as the brain in order to deliver light to deep targets for neuroscientific and neuroengineering applications such as optogenetics, in which light is used to activate or silence neurons expressing specific photosensitive proteins. However, an optical fiber is limited to delivering light to a single target within the three-dimensional structure of the brain. We here demonstrate a multiwaveguide probe capable of independently delivering light to multiple targets along the probe axis, thus enabling versatile optical control of sets of distributed brain targets.

Full recess integration of small diameter low threshold VCSELs within Si-CMOS ICs.

Oxide-aperture vertical-cavity surface-emitting lasers (VCSELs) have been integrated as individual device pills within the dielectric stacks of commercially produced silicon integrated circuits and monolithically connected electrically with the underlying circuitry using technology compatible with wafer-scale processing. The 55 microm diameter, 8 microm tall device pills were bonded in recesses etched to reveal buried contact/bond pads included in the IC layout; the surface was replanarized, contact vias formed, and interconnect metal deposited and patterned. The typical CW threshold current, 1 to 2.

High-density arrays of InGaN nanorings, nanodots, and nanoarrows fabricated by a template-assisted approach.

Dense, crystalline arrays of InGaN nanorings, nanodots, and nanoarrows have been fabricated on GaN substrates by template-assisted nano-area selective growth. To create the nanostructures, we have used nanoporous anodic alumina films as templates to pattern nanopores in an SiO2 transfer layer, and then used this patterned SiO2 layer as a template for nitride growth by metalorganic chemical vapor deposition. We have varied the diameter of the deposited nitride nanostructures from 35 to 250 nm by changing the initial anodic alumina template structure.