Pain and inflammation

37450-275 - Von Frey Hairs

Von Frey Hairs Von Frey Hairs
The Aesthesio® set of 20 monofilaments is based on the Semmes Weinstein monofilament set, but now features retrac­table head to protect the filament and allow the evaluator to carry a few around in a pocket. Used for evaluating cutaneous sensation levels. One of the most popular non-invasive techniques used.

The filaments are individually calibrated to deliver a target force, from 0.008 grams to 300 grams. Subsets of 5 and 6 filaments, as well as individual filaments are also available.

Rodents exhibit a paw withdrawal reflex when the paw is unexpectedly touched. The Aesthesio filaments can be used on the Plantar surfaces of the foot of a rat or mouse, and the animal will indicate sensation by pulling back its paw.

A metal platform, where laser-cut perforations form a mesh-like open grid of square holes ~5X5mm can be very useful when testing the rodent plantar surface, and is available as optional.  Intervening 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. 

    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

    Aesthesio® Tactile Sensory Evaluator Data Chart

    Color Evaluator Size Catalogue item Number Target Force (grams) Target Force* (milliNewtons)

    Theoretical

    Pressure

    Grams/Sq. mm

    Hand & Dorsal Foot Thresholds Plantar Threshold
    Green 1.65 514001 0.008 0.08 2.53 normal normal
    2.36 514002 0.02 0.20 4.39 normal normal
    2.44 514003 0.04 0.40 4.93 normal normal
    2.83 514004 0.07 0.70 5.53 normal normal
    Blue 3.22 514005 0.16 1.6 8.77 Diminished Light Touch normal
    3.61 514006 0.40 3.9 16.1 Diminished Light Touch Diminished Light Touch
    Purple 3.84 514007 0.60 5.9 18.4 Diminished Light Touch Diminished Light Touch
    4.08 514008 1.0 9.8 24.4 Diminished Light Touch Diminished Light Touch
    4.17 514009 1.4 13.7 27.9 Diminished Light Touch Diminished Light Touch
    4.31 514010 2.0 19.6 27.4 Diminished Light Touch Diminished Light Touch
    Red 4.56 514011 4.0 39.2 40.3 Loss of Protec-tive Sensation Diminished Light Touch
    4.74 514012 6.0 58.8 52.6 Loss of Protec-tive Sensation Diminished Light Touch
    4.93 514013 8.0 78.4 61.7 Loss of Protec-tive Sensation Diminished Light Touch
    5.07 514014 10 98.0 68.3 Loss of Protec-tive Sensation Loss of Protective Sensation
    5.18 514015 15 147 82.0 Loss of Protec-tive Sensation Loss of Protective Sensation
    5.46 514016 26 255 106 Loss of Protec-tive Sensation Loss of Protective Sensation
    5.88 514017 60 588 141 Loss of Protec-tive Sensation Loss of Protective Sensation
    6.10 514018 100 980 193 Loss of Protec-tive Sensation Loss of Protective Sensation
    6.45 514019 180 1760 222 Loss of Protec-tive Sensation Loss of Protective Sensation
    Or 6.65 514020 300 2940 292 Deep Protective Sensation Deep Pressure Sensation

    *calculated rounded numbers (conversion factor 9.80665)

    When the tip of a fiber of given length and diameter is pressed against the skin at right angle, the force of application increases as long as the researcher continues to advance the probe, until the fiber bends. After the fiber bends, continued advance creates more bend, but not more force of application. The Semmes Weinstein set of monofilaments provides an approximately logarithmic scale of actual force, and a linear scale of perceived intensity. They have a long history of effective use in clinical settings, and can be used to diagnose pathologies of hyper- or hypo-aesthesia.

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