How to embed and recover X-Headstage™?

In a previous post, we discussed the advantage of embedding headstage with the electrode. The biggest barrier for many to adopt this technique is to overcome the concern about re-usability. Here we offer some tips that will increase the success rate.

Dental acrylic is commonly used to anchor implant materials on the skull. Recovering the X-Headstage™ means separating the headstage, and ideally the electrode, from the acrylic at the end of the experiment, likely after the brain has been perfused and extracted. Dental acrylic can be softened and dissolved by acetone. Leaving the extracted implant overnight will soften the acrylic enough so that it can be peeled and broken off from the X-Headstage™. To minimize particles from clogging the connector pins during the soaking/detaching stage, it is recommended to apply a thin layer of Vaseline around the XHS probe connectors during the embedding step. Also during the application and dissolving step it is a good practice to plug in the cable to prevent accidentally dripping acrylic into the connector.  

In summary:

Embedding X-Headstage™

• Connect both probe connectors in the X-Headstage™ to cover and protect the connector region
• Apply Vaseline around X-Headstage™'s probe connectors
• Plug in a cable to X-Headstage™ system connector (HDMI or Omnetics) or protect this connector during the acrylic application phase to avoid dripping into the connector
• Some users reported and recommended a technique using a segment of a syringe tube as a container and outer barrier for holding the dental acrylic. Once the X-Headstage™ and electrode have been anchored, place this tube around the implant and then pour acrylic in the tube to hold and protect the whole implant. This tube also serves as a handling point to easily plugin the cable for data collection.

Recovering X-Headstage™

• Suspend the extracted implant in the middle of a beaker or jar. An old HDMI cable can be cut and attached to the lid of the jar by drilling a hole; Feed the cable through, and then apply epoxy/glue. Fill the jar with acetone just below the HDMI connector. To minimize the amount of acetone vapor leaking into the connector apply Vaseline around the connector joint. Leave to soak overnight.
• The solvent in the jar will be murky with particles falling to the bottom of the jar. Remove the extracted implant and carefully peel off the softened acrylic until EIB or probe PCB is exposed and can be removed. Additional acetone soak may be required.
• If necessary, clean any residual particles from the connector by spraying a gentle stream of acetone.
• Let the X-Headstage™ air dry.
• Verify the X-Headstage™ functionality using the impedance test module and brainwave simulator.  The headstage should be able to perform measurement and recording in the proper level.
• Your X-Headstage™ is good to go for another round of experiments!