Ugo Basile

Von Frey hairs, Semmes-Weinstein set of monofilaments

Code 37450-275UB

Used to measure the paw withdrawal reflex when the mouse or rat paw is unexpectedly touched. For evaluating mechanical allodynia and cutaneous sensation levels. Popular non-invasive technique.

Aesthesio® set of 20 monofilaments based on the Semmes Weinstein monofilament set. An ascending series of increasingly stiff filaments (from 0.008 to 300 grams). Features retractable head to protect the filaments, allowing a researcher to carry a few around in a pocket. An optional perforated metal grid platform is available that is comfortable for the animal and easy for viewing the target area.

Especially suggested for sub-gram forces (i.e., severe allodynia) although very time consuming and operator dependent.

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Features

Background of using the Von Frey hairs in experiments

  • Von Frey hairs (named after the German physiologist Max von Frey, 1852–1932). They have a long history of effective use in clinical settings, and can be used to diagnose pathologies of hyper- or hypo-aesthesia. 
  • The diameter of the nylon monofilaments determines the resistance of the monofilament to bending. 
  • For use on the plantar surfaces of the foot of a rat or mouse. The animal will indicate sensation by pulling back its paw.
  • A defensive response indicates using a lower filament force for the next test, while lack of a response indicates the need for a higher strength filament.
  • Based on the Semmes Weinstein monofilament set.
  • Subsets within the set of 20 probes distinguish pathologies on different parts of the body (foot, hand, lip, cheek, etc.)

Dynamic experiments, easy control

  • The filaments are individually calibrated to deliver a target force, from 0.008 grams to 300 grams.
  • The set provides an approximate logarithmic scale of actual force, and a linear scale of perceived intensity (refer to specification table)
  • Get a complete set up by adding the metal platform. Laser-cut perforations form a mesh-like open grid of square holes ~5X5mm can be very useful when testing the rodent plantar surface. The framework of the metal grid is approximately 1mm wide, comfortable to the animal and easy to view the target area of the paw.  The platform is coated with a polymer resin that is easy to clean and which will not be spoiled by fluids or waste materials.

Features&benefits of Von Frey hairs

  • Retractable filament: easy to carry and protected from damage
  • Effective use in clinical setting: used to diagnose pathologies of hyper- or hypo-aesthesia
  • Optional perforated platform available: for convenient stimulation of rodent plantar-surface