The SF-77B is a simple but highly effective stimulus solution delivery device for use in a variety of patch clamp and electrophysiology studies. Control and test solutions flow continuously through adjacent stimulus delivery tubes and a stepper mechanism selects which tube is directed at the preparation. The rapid response and nominal hysteresis of the stepper mechanism allows for very fast switching times. Complete solution changes are typically achieved within 20 msec for a large 700 mm step and times are significantly shortened as the step size is decreased.
Multiple Solution Studies
In the standard configuration, up to six different solutions are connected to a single input manifold which in turn is connected to one of three square glass stimulus ports. The three stimulus port design is superior to a two-port design in that complex solution exchange protocols can be brought to bear on the sample under study. Since the complete system is designed to accommodate three manifolds (one for each stimulus port) and each manifold can accommodate up to 6 feed lines, it is possible to immediately select between 18 different input solutions.
• Solution changes between stimulus ports occur within milliseconds
• Changes between solutions connected to individual port occur within 5 secs.
• Entirely new solutions can be added into any port with a waiting time of no more than 30 seconds.
• Cell is never required to pass through intervening solutions to get from control to test solution
Manual or External Control
The stepper mechanism can be manually controlled via the front panel or externally directed from your data acquisition program. Manually, the system can be stepped to 8 positions in 7 equally spaced steps. These same 8 positions can also be directly selected by applying an analog signal to the external analog input BNC or by passing a 3 byte word to the TTL input on the instrument rear panel.
Square Glass Stimulus Ports
The square glass tubes used for solution delivery significantly reduces mixing turbulence between solution flows allowing the SF-77B to be used for studies with both membrane patches and whole cells, even when the cells are not fixed to a substrate.
System Versatility
The design of the SF-77B permits the use of various size glass tubing for perfusion delivery.
SF-77B:
Standard System
(0.7 mm ID tubes)
The standard system is shipped with 3SG700-5 single-walled 3-barrel glass tubing which eliminates the need to glue individual barrels together. Spacing between barrels is 0.7 mm and step speed between adjacent barrels is typically 20 msec. Single barrel SG800-5 tubes (up to 5) can be used with the same holder.
SF-77BLT:
Large Tube System
(1.0 mm ID tubes)
Larger stimulus ports are required when using the SF-77B with larger cell structures such as the Xenopus oocyte. Solutions are delivered through 1.0 mm ID square tubes (SG1000-5) with barrel-to-barrel spacing of 1.4 mm.
SF-77BST:
1 msec Stepping
With Theta Tubing
The SF-77B has been successfully tested using theta style capillary tubing with a step speed of 1 msec between adjacent barrels. Standard 2 mm diameter theta tubing is pulled to a tip diameter of 300 mm with a spacing of 100 mm between barrels. In this design, placement of the pipette tip is critical due to the smaller perfusion stream. Since mechanical artifacts can be evident when using these small step sizes the motor drive voltage is adjustable at the rear panel.
Easy Set-Up
The stepper mechanism is compact, lightweight, and free of either mechanical or electrical noise. The mechanism connects to the control box with a 2 meter shielded cable and is provided with a mounting rod for attachment to a manipulator. Manifolds can support 2,4 or 6 inputs depending on the experiment. Solutions flow from reservoirs to the manifold through PE-50 tubing and PE-10 tubing is used to connect the manifold outputs to the glass tubes. We designed the VC-6M to accompany the SF-77B stepper. It conveniently fits inside a Faraday enclosure and is remotely controlled with the VC-6 controller. When purchased with the SF-77B, the complete package is discounted, see pages M136 and M137 for details.
These Fast-Step Systems are supplies with one 2 to 1 and two 6 to 1 manifolds. Other manifolds are available separately, see page M140. Note: Model SF-77B/5M: SF-77B may also be ordered as a 5 manifold system. Consult our technical support department for details.