Micropipette Holders & Electrochemical Half-Cells

WPI's microelectrode holder-half-cells couple fluid-filled glass micropipettes to high input impedance amplifiers. A Ag/AgCl pellet ( or a silver wire ) molded into the holder body provides stable potential. Electrical connection is made via male 2 mm pins or female 2 mm sockets. The pipette may be mounted axially or at right angles to the holder. Pipettes are held with screw-caps or rubber gaskets ( without caps ). Filling WPI microelectrode holders with electrolytes containing chloride results in stable electrode potential. Suitable electrolytes include KCl, NaCl and CaCl2. Holders are supplied for standard WPI single capillary tubing of 1.0, 1.2, 1.5 and 2.0 mm outside diameters.* The holder style you select will depend on your experimental application, space, and instrumentation.

Hints for selecting and ordering micropipette holders

1. Determine the required electrical connection on the holder: for example, if you wish to connect the holder to a 2 mm pin you should select a holder equipped with a 2 mm jack. Most WPI probes require a holder equipped with a 2 mm jack.

2. Decide on the required alignment of the electrical connection: either in-line with the glass pipette, or at a right angle to it. Space considerations in your experimental setup and requirements imposed by other pieces of equipment typically determine which alignment is appropriate.

3. Determine if you want to hold the glass pipette by a rubber gasket ( e.g., MEH1S ) or a screw-cap ( e.g., MEH3S ). Rubber gaskets offer easier insertion and removal of glass pipettes whereas screw-caps provide more secure mounts for micropipetters.

Most Popular Holders for Microinjection

MPH6S

MPH3

4. Choose a holder with either a silver wire or a silver/silver chloride pellet for the metal/liquid coupling. Silver/silver chloride pellets provide a more stable low-noise baseline which is important for low-noise DC recording. Pellets require the glass pipette and holder to be free of air bubbles to achieve a good connection. Silver wire holders are durable and are easier to use when the holder is equipped with a pressure port because the fluid in the pipette does not have to be filled to the top of the pipette to achieve a good electrical connection.

5. Choose a holder equipped with a pressure port only when you want to pressure inject liquid from the pipette. Two types of ports are available: 2.0 mm O.D. and standard "syringe-style" luer. The luer port is often recommended because it makes assembly and disassembly much easier. Quick-connect luer fittings for four common sizes of tubing ( 1/16", 3/32", 1/8", 5/32" I.D. ) are included with each luer-equipped holder.

6. Some non-WPI preamplifiers or headstages cannot be mounted on micromanipulators. In such cases, a holder equipped with a rod ( e.g., MEH8 ) permits the holder to be conveniently mounted on a micromanipulator.

7. Finally, remember to specify the O.D. of the glass you will be using when you place your order.

MEH6RF/SF is designed primarily for use with the Model 900A Micropressure System; EHB1 for use in electrode beveling; and MEH3SW for microtitration of chloride with a silver wire as the electrode and a solution of silver nitrate filling the holder. MPH models do not contain Ag/AgCl half-cells and are used for pressure injection of substances through microelectrodes. PicoNozzle, used for pressure injection with PV800 Series PicoPumps, includes an MPH6S holder - which may also be used to couple a micropipette to a syringe. APEH models are also designed for use in pressurized injection procedures.

*Call for custom orders designed for other glass diameters.

MICROELECTRODE HOLDERS WITH HANDLES (HANDLES ARE OPTIONAL)

MICROELECTRODE HOLDERS
	Electric Connection Angle	Connector	Half-Cell	Pressure Port	Screw Cap
APEH1	Right	Male	Pellet	No Port	2 Caps
APEH2	Right	Male	Wire	No Port	2 Caps
EHB1	Straight	Male	Wire	No Port	N/A
EHBF	Straight	Female	Wire	No Port	N/A
MEH145	45°	Male	Pellet	No Port	No Cap
MEH1F45	45°	Female	Pellet	No Port	No Cap
MEH1R	Right	Male	Pellet	No Port	No Cap
MEH1RF	Right	Female	Pellet	No Port	No Cap
MEH1S	Straight	Male	Pellet	No Port	No Cap
MEH1SF	Straight	Female	Pellet	No Port	No Cap
MEH2R	Right	Male	Pellet	Male Luer	w/Cap
MEH2RF	Right	Female	Pellet	Male Luer	w/Cap
MEH2RFW	Right	Female	Wire	Male Luer	w/Cap
MEH2RW	Right	Male	Wire	Male Luer	w/Cap
MEH2S	Straight	Male	Pellet	Male Luer	w/Cap
MEH2SF	Straight	Female	Pellet	Male Luer	w/Cap
MEH2SFW	Straight	Female	Wire	Male Luer	w/Cap
MEH2SW	Straight	Male	Wire	Male Luer	w/Cap
MEH345	45°	Male	Pellet	No Port	w/Cap
MEH3F45	45°	Female	Pellet	No Port	w/Cap
MEH3FW45	45°	Female	Wire	Port	w/Cap
MEH3W45	45°	Male	Wire	No Port	w/Cap
MEH3R	Right	Male	Pellet	No Port	w/Cap
MEH3RF	Right	Female	Pellet	No Port	w/Cap
MEH3RFW	Right	Female	Wire	No Port	w/Cap
MEH3RW	Right	Male	Wire	No Port	w/Cap
MEH3S	Straight	Male	Pellet	No Port	w/Cap
MEH3SB	Straight	Banana	Pellet	No Port	w/Cap
MEH3SBW	Straight	Banana	Wire	No Port	w/Cap
MEH3SF	Straight	Female	Pellet	No Port	w/Cap
MEH3SFW	Straight	Female	Wire	No Port	w/Cap
MEH3SW	Straight	Male	Wire	No Port	w/Cap
MEH6RF	Right	Female	Pellet	2.0-mm Port	w/Cap
MEH6RFW	Right	Female	Wire	2.0-mm Port	w/Cap
MEH6SF	Straight	Female	Pellet	2.0-mm Port	w/Cap
MEH6SFW	Straight	Female	Wire	2.0-mm Port	w/Cap
MEH7	Right	Male	Pellet	2.0-mm Port	w/Cap
MEH7W	Right	Male	Wire	2.0-mm Port	w/Cap
MEH8	Right	Male	Pellet	No Port	w/Cap
MEH900R	Right	Male	Pellet	2.0-mm Port	w/Cap
MEH900S	Straight	Male	Pellet	2.0-mm Port	w/Cap
MPH1	-	None	None	Female Luer	w/Cap
MPH3	-	None	None	Male Luer	w/Cap
MPH4	-	None	None	2.0-mm Port	w/Cap
MPH6R	Right	Male	Wire	Female Luer	w/Cap
MPH6S	-	None	None	Female Luer	w/Cap

Specify O.D. of Glass (1.0, 1.2, 1.5 or 2.0 mm) When Ordering

HANDLES and ACCESSORIES (not included) Handle #2505 is for use with WPI manipulators. The smaller diameter handle #5444 is required for use with Narashige and Zeiss manipulators.
2505	0.25 in. (6.3 mm) diameter handle
5444	0.16 in.(4.0 mm) diameter handle
G01-100	Replacement gasket 1.0 mm Package of 100
G02-100	Replacement gasket 1.2 mm Package of 100
G03-100	Replacement gasket 1.5 mm Package of 100
G04-100	Replacement gasket 2.0 mm Package of 100
1571	Clear Silicone Rubber Sealant ( 4.7 oz )