title: Vibrotactile characteristics of different tissues in endoscopic otolaryngologic surgery - in vivo and ex vivo measurements.
abstract: The measurement of mechanical tissue impedance by determining resonance frequency with the help of a tactile sensor is one method of compensating for sensory deficits in endoscopic surgery. In principle, this electromechanic vibrotactile sensor can be integrated into an operating instrument. The operator would thereby receive indirect feedback on the tactile properties of the tissue. We examined freshly resected tissues using the first prototype vibrotactile sensor. Measurements on resected carcinoma of the oropharynx demonstrated the possibility of differentiating between carcinoma, healthy mucosa and carcinomatous-infiltrated mucosa. Subsequent in vivo measurements in the oropharynx and oral-cavity regions of 20 patients confirmed these results. We found that, in the oral cavity, tumours of > 1 cm diameter could be distinguished from the surrounding mucosa. Tumours of the soft palate and tonsillary region could not be clearly delimited, because of stimulation of the surrounding tissue.