Thumbtack Probe

The 24 channel Thumbtack Probe* is a linear probe for chronic use designed to span cortical layers running parallel to the surface of the brain. It is effective for both field potential and single-unit recordings, and is often used in medium to large animals like primates.

The microelectrode array is embedded in a polyimide-epoxy substrate with a total outer diameter of 500µm. The polyimide-epoxy composite shaft provides the structural integrity to penetrate neural tissue and hold the electrode contacts in precise alignment. A thin, circular silicone sheet is attached at the top of the microelectrode, perpendicular to the axis the probe, to hold the Thumbtack Probe in place, while surface tension between the silicone sheet and the cortical surface assists in securing the probe in position. Output leads are bent at 90° at the top part of the anchoring sheet, and are then embedded in a 10cm silicone cable/tube which terminates in a 36-pin 0.25” pitch Omnetics connector.

The Thumbtack Probe is designed with a rounded tip to minimize the chance of blood vessel perforation. The precise linear arrangement of the electrode sites enables current source density analysis of the field potential signals as recorded from laminar neural structures.

The platinum/iridium electrode recording sites are available in 15 and 40µm diameter options. The small electrode site diameter (15µm) enables effective single-unit recording, while a unique etching process of the electrode surface results in lowered impedances without significantly changing the overall surface area of the exposed recording site. The result is a small site suitable for resolving single units coupled with low impedance for a better single-to-noise ratio.

If you would like to learn more about our Thumbtack Probe, we invite you to conact a Plexon Sales Engineer.