LAUSR

Dermographism is a condition characterized by a weal response to a combination of pressure and traction on skin surface, and its diagnosis is based on medical history, clinical criteria and provocation test. The Dermographic Tester®, a pen‐sized tool containing a spring‐loaded blunt tip, is the most widely used instrument for the provocation test, and it exerts increasing pressures on the skin surface according to an arbitrary units (AU) scale. Analysing the mechanism of function and trying to convert the AUs to SI units (g/mm2), we found that this instrument had some defects and limits that would compromise a true and repeatable quantification of the weal response threshold. Consequently, we decided to develop a new instrument, the Digital Dermographic Tester (DDT), which is engineered with an inside force sensor to implement features lacking in the current tools, in the hope of enhancing the precision of the provocation test.