Applying a negative pressure to the inner cavity of the suction electrode via the small side port draws the tissue to be recorded from, or stimulated, next to or into the end of the suction electrode (either via a short glass capillary pipette, a disposable pipettor tip, or a short section of tubing). The inner cavity also contains a silver wire connected to a jack on the rear of the electrode. Outside of the cavity is a short segment of wire that can be utilized as the reference electrode, or a silversilver chloride pellet with wire lead can be soldered to the suction electrode’s reference wire to complete the circuit. The suction electrode is offered with either a conductive EMI shield coating, or with a separate ground wire, depending on your preference.
With the suction electrode, it is easy to record extracellularly from very small hearts, insects, intestinal nerves, as well as stimulate muscle tissue. If the glass capillary is removed and replaced by some small diameter tubing, it is possible to record from tissues or animals while they move by contracting, expanding, or changing position. Instructions are also included on how to record using a common disposable pipettor tips, thereby eliminating the need and cost involved when using pulled glass pipettes.
Accessories packaged with each electrode include a cable for connecting to the iWire-Bxx recorders , a short section of tubing allowing for easy connection to a luer suction source, syringe, 3-way stop-cock and several disposable pipette tips that make recording by students simple.
When using a disposable pipette tip as an electrode
Remove the Suction Electrode from the box. Note the glass capillary tubing at one end.
Carefully unscrew the nylon threaded tip through which the glass capillary tubing passes.
When the nylon threaded tip is free, remove the tip and the glass capillary tubing, leaving the silver wire in place.
Remove the small O-Ring and the nylon threaded tip from the end of the glass tubing. Replace the small O-Ring into the hole, and reinsert the nylon tip.
Place large O-Ring over end of suction electrode body.
Thread the 20uL pipette tip over O-Ring. Place the 1uL pipette over the larger pipette. This second pipette tip can be replaced during the course of the experiment if it becomes clogged, without removing the larger base pipette tip.
Keep the silver wire as close to the end of the capillary tubing as possible for best recording and stimulation. If the tube is not the right length, loosen the nylon tip and adjust the tube accordingly.
Place the assembled suction electrode into the micromanipulator.
Attach a length of appropriate tubing to the side suction port for use to apply negative pressure.
Place the capillary glass tube or the pipettor tip opening into the electrolyte and draw up some of the electrolyte into the glass tubing.
Connect the appropriate signal, reference, and ground jacks to the amplifier inputs. The silver wire inside the suction electrode is connected to the central 2mm jack. The black reference wire is connected one of the 1.6mm jacks. The conductive outer shield (if present) or the bare ground wire is connected to the 1.6mm jack marked with a small “G”
Move the tube close to the tissue to be recorded or stimulated. Aspirate the tissue into or next to the electrode tip before recording or stimulating.
Rinse out the suction electrode with distilled water after each use.