What are WPI Standard Glass Capillaries?

WPI Standard Glass Capillaries are high-purity borosilicate glass tubes engineered for precision micropipette fabrication. These capillaries serve as the essential raw material for pulling patch clamp pipettes, sharp electrodes, injection needles, and recording electrodes — forming the foundation of electrophysiology, microinjection, and intracellular recording workflows across neuroscience and cell biology labs.

Available in a comprehensive range of outer diameters (1.0, 1.2, 1.5, and 2.0 mm) and lengths (3, 4, and 6 inches), WPI glass capillaries are compatible with virtually all standard micropipette pullers and offer consistent wall thickness and optical clarity essential for reliable, reproducible results.

Key Features

• High-Purity Borosilicate Glass: Manufactured from premium borosilicate tubing with tight dimensional tolerances, ensuring consistent pull characteristics and minimal lot-to-lot variability critical for reproducible patch clamp and injection experiments.
• Wide Size Range: Available in 1.0, 1.2, 1.5, and 2.0 mm outer diameters across 3-, 4-, and 6-inch lengths, covering the full spectrum of pipette types from fine sharp electrodes to large injection needles.
• Filament Options: Filament-containing (F) variants feature an internal glass fiber that wicks solutions to the pipette tip by capillary action, dramatically simplifying backfilling of patch clamp electrodes and injection needles — no special tools needed.
• Universal Puller Compatibility: Designed to work seamlessly with WPI's PUL-1000 and other standard horizontal and vertical pullers, giving consistent pull geometry and tip diameter with minimal parameter adjustment.
• Ready-to-Use Cleanliness: Supplied clean and ready for immediate pulling — no pre-washing or preparation required under standard laboratory conditions.
• Bulk Packaging: Available in packs of 100 capillaries, providing excellent value for high-throughput recording or injection studies.

Choosing the Right Capillary Size

Selecting the correct outer diameter and length depends on the application and the micropipette puller being used. As a general guide: 1.0 mm OD capillaries are ideal for very fine sharp electrodes and intracellular recording; 1.2 mm OD is the most widely used size for patch clamp whole-cell and perforated-patch configurations; 1.5 mm OD is favored for pressure injection and single-channel recordings; and 2.0 mm OD is chosen when large-bore or thick-walled pipettes are required for injection or nucleated patch applications.

Filament vs. Non-Filament

• Filament (F suffix — e.g., 1B150F-4): Contains a thin glass fiber fused to the inner wall that draws solution to the tip by capillary action. Strongly recommended for patch clamp and any application where backfilling from the tip is impractical. The filament ensures bubble-free filling every time.
• Non-Filament (no F suffix — e.g., 1B150-4): Simpler construction with no internal fiber. Preferred for applications using viscous or fluorescent internal solutions where the filament might interfere, or where pipettes are front-filled under positive pressure.

Compatibility with WPI Pullers

All WPI Standard Glass Capillaries are fully compatible with the WPI PUL-1000 horizontal puller. Simply load the capillary, select the appropriate program, and pull to your desired tip geometry. For best results with the PUL-1000, WPI recommends starting with the 1B150F-4 (1.5 mm OD, 4-inch, filament) as an all-purpose starting point.