Patch Clamp Ephys Rig Maintenance: Easy Cleaning Hacks
Golden Rule: Prevention is better than the Cure - keep your electrophysiology rig clean, dry and tidy
Being careful and aware of how you and your colleagues handle the rig beats all other measures. Keep a record of standards (photographic and descriptive lists or checklists) and compare performance against these standards frequently (best practice to schedule this in your diary). This way you can address deteriorating optical and mechanical performance before it affects your data acquisition.
Dirt, dust and saline spills are the regular culprits, but you can prevent it from impacting your research. Some crucial and inexpensive preventative measures are:
- Invest in a microscope dust-cover when it’s not in use
- Invest in the OpenFlowCtrl Peristaltic Pump, with automatic shut-down when spillages are detected.
- Install a Rig Guardian Spill Detector to notify you of spillages When you’re notified of a spill, you can clean it immediately.
- Install spill-protection sheets, membranes and gutters underneath your microscope stage. Some manufacturers provide these with their kit, but you can improvise a DIY solution that works well.
Dirt on Microscope Optics - how to remove unwanted elements from your optical path
When you do notice spots in the optical path, it helps to have a systematic approach to identifying its location to address it. Here’s an approach we recommend:
- Now focus on a clean cover slip – change focus and X/Y position of the sample stage to a point where any spots on the cover slip are out of focus/view. This way you won’t confuse cover-slip spots with optical path dirt).
- First clue – is the spot is visible on both the camera and through the eyepieces? We’ll If it’s visible on the camera, but not through the eyepieces, the location is likely to be on the sensor-chip or glass covering it. To confirm, slightly rotate the camera – if the image moves with a stationary spot, the dirt is likely to be on the camera surfaces. This is dangerous territory to fix yourself – discuss with the manufacturer first
- If the spot is not on the camera (after having rotated it), it may be on any aftermagnification/demagnification lenses between the tube lens and the camera. Carefully loosen clamping screws and rotate/remove the modules to identify which component is the cause. Remove the identified component and inspect to see if you can detect the spot. To clean it, you can follow the guidelines demonstrated here.
- If the spot is only visible via an eyepiece, it’s easy to point to the particular eyepiece as the source by rotating it whilst looking through it. The video above explains eyepiece cleaning in detail.
- The next checkpoint would be on the objectives – typically the front lens or the back aperture lens…Switch between objective magnifications. If the spot is only visible on one of the objectives, you’re likely to have diagnosed the source being the objective in question. To clean it, use the guidelines in this video
- If you still haven’t identified the source, the culprit may be the condenser. Move it up and down and rotate the front lens (if possible) or loosen the clamp and rotate the condenser. If rotation makes the dirt move, you’ve hit a home-run.
The above measures would solve the majority of issues on the optics. More in-depth diagnosis may be necessary, but this is beyond the scope of this post. We next change our gaze towards a serious villain for neurophysiologists…
Crystalized/dehydrated salt solution on the optics, mechanics and surfaces of your electrophysiology setup
Despite your best efforts, working with perfusate over long hours amidst potential distractions makes the odd saline spill inevitable. The potential damaging aftermath can be minimized by cleaning it immediately.
This can be easier if you integrate a smart spill-alarm into your setup. When you notice a spill:
- Make sure to soak up all excess solution with a paper towel or another absorbent cloth.
- In the case of non-optical surfaces, use a cloth damped with water to wipe it clean afterwards, and dry properly. For optics, an absorbent cloth or paper towel for excess solution would do as well, followed by a soft cleaning method following guidelines you’d follow with dust or other spots.
If you don’t have a spill detector installed on your rig, it is easy for saline spills to go unnoticed. You will eventually get buildup of salt on the setup. This can severely damage your optics, but also moving mechanics and metal surfaces, with under-the-microscope translation stages and optical table breadboard surfaces being typical soft targets.
How do you clean salty deposits/residue from mechanical parts or metal surfaces? Some guidelines:
- Approach this with care, patience and with soft hands. It’s good practice to spot-test a small amount of the solution on an inconspicuous area to make sure it doesn’t discolor the surface that you are planning to clean.
- Combine equal parts of white vinegar and rubbing alcohol (70%) in a spray bottle.
- Spray the target area with the solution and let it soak in for a few minutes.
- Wipe any excess solution and salt away with paper towel and repeat the previous step until salt is removed.
- If some of the residue marks are stubborn, scrub with a soft-bristled scrub brush. If some areas are corroded, use a soft-bristled brass-wire brush. If the metal/coating has a grain, be sure to move scrub along the direction of the grain. Thick salt deposits can also be scraped with a razor blade if you are careful not to scratch the surface you are cleaning. Spray more of the solution onto the surface as you work if the mixture begins to dry or dissipate.
- Spray clean water on the area or onto a soft cloth, and wipe the treated area thoroughly.
- Use a dry, clean soft cloth to buff dry non-porous surfaces. If it’s moving parts, contact the manufacturer to enquire about best lubricant (usually grease, but WD-40 lubricant often does a good job).
We are curious about measures you’ve taken to prevent damage to your setup, especially with regards to gutters and membranes. Please send us pictures of your designs…we’ll publish it on our social media channels for others to copy/comment
