Closing straws reliably

Today, it is standard to close straws for cryopreservation of gametes or embryos with an electric sealer. The heat required to seal a straw is either generated directly by heated sealing jaws, or indirectly through ultrasonic waves. Ultrasound causes the adjacent inner walls of a plastic straw to vibrate locally at a high frequency until they fuse due to the frictional heat.
Tightness should not be a coincidence
Many welding devices allow countless application variants, leaving the operator with unanswered questions: What welding temperature should I choose? How deep and at what angle should I insert the straw between the sealing jaws? How long and how strong should I press the welding jaws together? The more degrees of freedom, the more difficult it is to achieve consistent and reproducible results when sealing straws.

Consequently, the tightness of straws may crucially depend on the "human factor". In the worst case, smallest openings remain in the welding seam, allowing liquid nitrogen to enter the straw. At ultra-low temperatures, this goes unnoticed. It is during thawing that liquid nitrogen evaporates and suddenly expands its volume by a factor of 694. The straw will explode, not only destroying the valuable contents but endangering the operator's eyes.
Minitube CryoSealer for easy and reproducible sealing of straws
With the CryoSealer, Minitube has developed a semi-automatic ultrasonic welding device for all straws with the common outer diameters of 1.96 and 2.85 mm which standardizes and automates many parameters which are critical for obtaining tight welding seams:
  • No heat spreading: tightly focused heat generation protects the contents of the straw
  • The welding time can be adjusted exactly to the material used
  • Separate insertion guides position 0.25 and 0.5 ml straws perpendicularly between the welding jaws
  • A longitudinal stop defines the insertion depth of the straws
  • The welding jaws close automatically and keep to the welding time exactly
  • The contact pressure during welding is preset

The CryoSealer has achieved impressive results in leakage tests. The device minimizes potential errors, setting an important starting point for successful cryopreservation procedures!

We would be happy to advise you in more detail.
Closing straws reliably