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Summary of Contents for WPI 900A
- Page 1 WORLD PRECISION INSTRUMENTS Instrumenting scientific ideas INSTRUCTION MANUAL 900A Micropressure System Serial No._____________________ www.wpiinc.com 071618...
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Page 3: Table Of Contents
Viewing and Imaging ......................9 Alarm ............................10 Liquid Trap ..........................10 OPERATING INSTRUCTIONS .......................11 Setting Up and Powering the 900A ................11 Zero Adjusting the Pressure Pod to Ambient Pressure........... 12 Applying Pressure and Vacuum and Re-zeroing ............12 Seting Up the Measurement Site ..................14 Preparing the Microelctrode and Microelectrode Holder ........ - Page 4 MAINTENANCE ..........................27 Cleaning .............................27 Replacing the Fuse ........................27 Service............................27 ACCESSORIES..........................28 SPECIFICATIONS ..........................29 DECLARATION OF CONFORMITY ....................30 WARRANTY .............................31 Claims and Returns ........................31 Repairs ............................31 World Precision Instruments...
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Page 5: About This Manual
The micropressure system includes a main electronic Control Unit, Probe and Pressure Pod. Fluid-filled glass micropipettes (supplied by the user) pulled to an outside diameter of 2–5µm act as microelectrodes when paired with the 900A sensing probe to complete a circuit across the measurement location. A pressure source supplying up to +500mmHg of pressure and a vacuum source supplying up to –300mmHg vacuum interfaces through the Pressure Pod to maintain a null pressure,... -
Page 6: Parts List
After unpacking, verify that there is no visible damage to the sensor. Verify that all items are included: Each 900A system includes the following components: (1) 900A Micropressure System Control Unit with power cord (1) 900AP Probe (1) 900APP100 Pressure Pod or 900APP Pressure Pod (1) 900A Startup Kit, which includes: (1) 1 ft. -
Page 7: Other Required Items (Not Included)
Concealed damage should be reported at once to the carrier and an inspection requested. Please read the section entitled “Claims and Returns” on page 31 of this manual. Please contact WPI Customer Service if any parts are missing at 941.371.1003 or customerservice@wpiinc.com. -
Page 8: Instrument Description
The 900A senses the ionic alteration caused by the pressure change. The 900A then signals the Pressure Pod to maintain the circuit to the equilibrium (null) value. -
Page 9: Response Rate
Using Sensitivity and Damping to Correct Oscillations All feedback control systems tend to become unstable and oscillate under certain conditions. The 900A provides two controls for combatting instability and oscillation— Sensitivity and Damping. Decreasing Sensitivity or increasing Damping often reduces or stops oscillations. The proper settings for both controls depends on the particular application. -
Page 10: Circuit Discussion
Circuit Discussion The 900A consists of an oscillator, head stage, phase detector, buffer amplifier, pressure transducer and Pressure Pod. Fig. 3—(Right) The circuit is complete when the reference electrode is immersed in the solution at the measurement site, along with... -
Page 11: Getting Started
Microelectrodes The microelectrodes used here are glass pipettes filled with an electrolyte solution. The shape of the microelectrode tip significantly affects the 900A’s response. Shorter tipped microelectrodes that do not have an excessively long taper (similar to a patch clamp tip) work best. Microelectrodes with internal tip diameters of 2-5µm are suggested (WPI #TIPTW900A). -
Page 12: Salt Solutions
For example, if the microelectrode is filled with 1 M NaCl, the external bath should be 0.1 M NaCl. NaCl is a common choice for 900A users. KCl has been used well in this system, though it should be noted that KCl is a well-known agent used to stop the heart. -
Page 13: Experimental Containers
The agarose is covered with electrolyte bath with the reference ground electrode secured within or over the agarose. Z-molds (WPI #Z-MOLDS) can create well defined depressions in the agarose that greatly help when stabilizing organisms or other vessels. The depressions can also allow for conductivity between the microelectrode and the reference electrode so a shallow layer of electrolyte bath can be used. -
Page 14: Alarm
Quick response to the alarm prevents this damage from occurring. When an alarm sounds, return the 900A to the Zero Set position. This will bring the system out of dynamic operation and into a “safe mode.” See “Operating Instructions” on page 11 for more information. -
Page 15: Operating Instructions
NOTE: The CKT and CHAS (circuit and chassis) ground connections should be electrcally connected with a metal strap, so either ground connection is suitable. Connect the power cord to the receptacle on the rear panel of the 900A. Plug the other end into a wall socket. -
Page 16: Zero Adjusting The Pressure Pod To Ambient Pressure
11. Turn the power switch on and let the system warm up for 15 minutes. 12. Using a BNC cable, connect the data acquisition port marked Pressure Signal on the right side of the 900A front panel to an oscilloscope or data acquisition system. Zero Adjusting the Pressure Pod to Ambient Pressure Verify that the Loop Status is set to Zero Set and the system has warmed up for at least 15 minutes. - Page 17 Fig. 9—Remove your finger to open the To Micropipette pressure port. NOTE: If you are unable to get a 0 reading, turn off the 900A, disconnect the pressure and vacuum supplies and repeat the previous steps in this section.
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Page 18: Seting Up The Measurement Site
Chamber. The level should be enough to cover the Ag/AgCl pellet in the CAL900A. Connect the integrated blue ground (Ag/AgCl pellet) connection of the CAL900A to the CKT or CHAS ground connection on the 900A using a banana to 2 mm pin adapter (WPI #13776). - Page 19 900A Micropressure System Backfill the shank of the micropipette using a microelctrode filling needle and syringe. WPI’s flexible MicroFil filling needles (WPI #MF28G67-5) are ideally suited for this application. Do not allow air bubbles to remain in the pipette. Fig. 11—Attach the MicroFil to a syringe filled with with solution. Insert the MicroFil into the micropipette all the way to the tip.
- Page 20 Insert the microelectrode into the microelectrode holder and tighten the cap. Fig. 13—Press the glass micropipette into the electrode holder. Check again to be sure that no air bubbles remain in the microelectrode or the microelectrode holder. Tightening the cap can expose any otherwise unseen bubbles.
- Page 21 CAL900A chamber wall. Verify that the Loop Status switch is at Zero Set. Insert the 900A Probe into the microelectrode assembly. The Null Detector will go to a hard left position.
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Page 22: Adjusting Electrode Resistance
zero, the pipette tip resistance is less than that indicated on the Electrode Resistance Dial. When the Null Detector is at zero, the resistance of the pipette is the value that appears on the 10-turn potentiometer (Electrode Resistance Dial). Needle Deflected Left Needle Deflected Right Needle On Zero Tip resistance is greater... -
Page 23: Connecting The Pressure Pod To The Microelectrode Assembly
900A Micropressure System CAUTION:The system will NOT operate correctly with an air bubble in the system. Connecting the Pressure Pod to the Microelectrode Assembly Prepare a 12-inch (30 cm) or shorter length of small-bore tubing. This will be used to connect the Pressure Pod to the microelectrode holder. - Page 24 Turn the Electrode Resistance dial down to the original setting, as described above. Turn the Loop Status switch to Auto. The 900A will then adjust the pressure inside the micropipette back to the original value by expelling the dilute electrolyte bath solution, to decrease the tip resistance to its original value.
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Page 25: Adjusting The Sensitivity And Damping
900A Micropressure System If adjusting the Electrode Resistance dial or changing the Loop Status switch to Auto has no effect, check the placement of the microelectrode, the reference electrode, the liquid level in the microelectrode holder and all connections. NOTE: Take care not to leave the Loop Status switch on Auto, to avoid discharging the contents of the microelectrode. -
Page 26: Calibrating The Pressure Signal
Pressure Offset meter reading is inconsequential. Fig. 21—Turn on the pressure offset and use the dial to bring the 900A display to zero. If you are not taking immediate readings, switch the Loop Status control to the Zero Set position. -
Page 27: Moving The System To The Recording Site
This is done by adding known pressure pulses into the CAL900A chamber through the Luer fitting. This pressure will be sensed by the 900A circuit and will be output as voltage from the Pressure Output BNC port. - Page 28 Again turn the Loop Status to Auto. The Null Detector should deflect back to near zero, as the 900A controls the pressure in the microelectrode to generate the tip resistance preset on the Electrode Resistance Dial. Monitor the signal on the recording device. If the Null Detector reading or the pressure reading is unsteady, adjust the Damping and/or the Sensitivity dials.
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Page 29: Setting Pressure Mode
900A Micropressure System NOTE: if the tip becomes blocked, the circuit will be open and the alarm will sound. A short (<1 s) signal is common when advancing across a biological membrane. Signals longer than one second should be mitigated by immediately setting the Loop Status to Zero Set to avoid damage to the system. -
Page 30: Measuring Dc Potential
Measuring DC Potential Although the primary function of the 900A is to measure pressures, it can also be used to measure DC potential at the microelectrode site. Connect a recording device to the Follower Output BNC connector. Fig. 25—Measure DC potential at the microelectrode site using the Follower Output. -
Page 31: Maintenance
You can easily replace the fuse in Control Unit. The part numbers for replacement fuses are: #3822 for 110V line power #6408 for 220 V line power Service Contact World Precision Instruments at (941) 371-1003 or wpi@wpiinc.com for all service needs. World Precision Instruments... -
Page 32: Accessories
Pressure Manometer (100 psi) SYS-PM100R Pressure Manometer (100 psi), Rechargeable TIPTW900A Prepulled Micropipette for 900A, 2 µm Tip Z-MOLDS Microinjection and Transplantation Molds *Electrode holders may be ordered to accommodate any of the following glass sizes: 1.0, 1.2, 1.5 and 2.0 mm diameter. -
Page 33: Specifications
900A Micropressure System SPECIFICATIONS This unit conforms to the following specifications: 900APP Pressure Range ................+500 to –300 mmHg 900APP100* Pressure Range ..................±100 mmHg Linearity ..................... < ±0.5% from a straight line Stability ................+/- 0.1 mmHg up to 1 hour or more Accuracy ....................... -
Page 34: Declaration Of Conformity
DECLARATION OF CONFORMITY World Precision Instruments... -
Page 35: Warranty
WPI shall not be liable for any damage to data or property that may be caused directly or indirectly by use of this product. - Page 36 International Trade Center, 175 Sarasota Center Blvd., Sarasota FL 34240-9258 Tel: 941-371-1003 • Fax: 941-377-5428 • E-mail: sales@wpiinc.com 1 Hunting Gate, Hitchin, Hertfordshire SG4 0TJ Tel: 44 (0)1462 424700 • Fax: 44 (0)1462 424701 • E-mail: wpiuk@wpi-europe.com Germany Saarstraße 23, D-61169 Friedberg (Hesson), Germany Tel: +49 (0)6031 1602171 •...
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