739 Electronic von Frey SENSELab Transducer

The Somedic / SENSELab Electronic von Frey Transducer is built around a highly sensitive and compact sensor element housed in a stainless steel tube. This gives a very sturdy transducer with high sensitivity, rapid reaction time and minimal movement artifacts.

To the transducer, any of the von Frey probe tips can be mounted. The probe tips are similar in size to the conventional von Frey filaments, but contrary to the von Frey filaments, they shall not buckle. Instead they shall transfer the application force to the transducer with minimal mechanical deformation of the probe. Thus during the application, the contact area remains the same. For a normal von Frey hair, the buckling of the hair can change the contact area significantly, not only in size, but also from a flat tip to a sharp edge. This change in sensation, with the conventional von Frey filaments, is avoided with the electronic von Frey transducer.

To avoid buckling, only the outermost 3 to 5 mm of the probe tips are similar in diameter to the von Frey filament, the rest of the probe tips is constructed from stainless steel tubing, with constant diameter. To further avoid buckling, the material in the outermost part of the probe tip can also be made of stainless steel, instead of a nylon monofilament.

This type of electronic von Frey transducer is usually superior in most types of animal studies and the only choice where information about timing and intensity of the stimulus is required. But one aspect of the rigidity of the probe tip has to be considered. To access the lowest of the touch perception thresholds in humans, the flexibility of the conventional von Frey filament is required to smooth out the vibration and tremor in the hand of the investigator. Thus the electronic von Frey is not recommended for use below 0,1 to 1 gram, depending on the stability of the investigators hand.