title: Fabrication of glass micropipettes: a semi-automatic approach for trimming the pipette tip.
abstract: Micropipettes as research instruments are well established in cell biology, including blood rheology. However, the experimental results are, to some extent, dependent on the quality of the pipette itself; it is usually critical to have the desired pipette internal diameter and a perpendicular tip. Pipette fabrication is a two-step procedure involving: a) the pulling of the pipette from a glass capillary; b) the trimming of the pipette tip. A common method to trim and fracture the pipette tip is the use of a melted glass bead on a heated tungsten wire. Previous devices using this method were often associated with problems because the heated wire varied in length with temperature. As a result, the bead together with the attached pipette tip moved markedly and thus hampered the possibility to obtain a perpendicularly cut pipette tip. An improved design, based on the same principle with a melted glass bead, is thus suggested; it eliminates the problem with a moving glass bead and, in addition, allows semi-automatic pipette trimming by utilizing the heat-induced elongation/retraction of the heated wire to fracture the tip without requiring manual assistance. Furthermore, a simple pipette storing technique is suggested, based on standard laboratory utensils, in order to more easily handle fragile pipettes without risk of breakage.
authors.affiliation: Department of Histology and Cell Biology, University of Umeå, Sweden.
authors.forename: K G
authors.initials: KG
authors.lastname: Engström
authors.forename: H J
authors.initials: HJ
authors.lastname: Meiselman
mesh_terms: D001790:Blood Physiological Phenomena; D004867:Equipment Design; D004912:Erythrocytes / Q000502:physiology; D005898:Glass; D006801:Humans; D012212:Rheology / Q000295:instrumentation*