Probe Package

The two parts of a probe: a single-shank array on an A32 package (top) and on a CM16 package (bottom), with breakout ground and reference wires.

The package has four parts. The interconnect runs from the array's bond pads to the connector: a rigid printed-circuit board (A-Series), a flexible polyimide cable (Hybrid), or none at all where the connector sits on the assembly (CM, X-Series). The connector is what a headstage mates to: DIP-16, Omnetics 16-, 32- and 64-pin and Samtec 40-pin mate a SmartLink headstage directly, and an X-Series headstage through an X-Series connector adapter; Molex X3 and Panasonic 96-pin on X-Series packages mate an X-Series headstage directly; Hirose on the ZIF and Vector VZ builds mates TDT ZIF-Clip headstages. The covering encapsulates the bond region, with a housing where the preparation needs one. And the ground and reference wires are brought out beside the signal pins. Activus packages integrate the digitizing headstage chip in the assembly and terminate in micro-HDMI for XDAQ or Smartbox, or in a 12-pin Omnetics SPI connector for Intan-compatible systems; Activus SiNAPS packages terminate in a 50-pin Samtec connector to the SiNAPS interface box. Stimulation through a passive package uses an X-Series stim-record headstage on XDAQ in record-and-stimulate mode.

A package name reads as the series and the channel count: A32 is an A-Series package with 32 channels, CM32 a CM package with 32, H64 a Hybrid with 64. A leading O marks an optoelectrode build with an optical fiber (OH32LP), MR an MRI-conditional build with non-magnetic parts (MRA16), and VC a chronic Vector build (VC64). The package is built onto the array at assembly, so it is decided once; a probe in a different package is a different product.

The package decides how the probe is held and what else shares the trajectory: a rigid interconnect for a stereotaxic holder (A-Series); a connector on the assembly with no cable for a chronic mouse implant (CM); a flexible cable between array and connector for a floating implant or a microdrive (Hybrid and the X-Series H builds); a support shaft for a deep target in a large animal (Vector, DBS); an optical fiber (optoelectrode builds), a fluidic channel (drug delivery), a second array bonded back to back (Fusion), or non-magnetic parts (MRI-conditional builds). It also decides how much the implant weighs on the animal, from 0.14 g for a Hybrid to several grams for an A-Series board, and how long it survives, because the bonds from the array pads to the interconnect, the insulation over them, and the body carry the mechanical load the array never sees. Package quality is part of probe quality. NeuroNexus offers fourteen package series, each with its own entry; how acute or chronic, the subject, and the headstage select one is worked through in Choosing a Probe Package, the pairings with headstages and adapters in Connecting a Probe Package to a Headstage, and the chain the package feeds under the recording chain.