A resonance frequency technique to determine the energy absorbed in stratum corneum in vivo

Summary

A cantilever-mode transducer was designed to determine the energy absorbed in stratum corneum. The measurements were made in a frequency range of 700–800 Hz. The softness of stratum corneum was measured in terms of loss tangent (tan δ), a dimensionless number. An acoustic spectrometer was used to determine the resonance frequency, and the results obtained were recorded on an X—Y recorder. The vertical displacement of the arm of the transducer was controlled by attaching a ring weight to the horizontal portion of the arm. This permits the measurement of stratum corneum softness whether it is close to a bone or to fatty tissue.

The method was used to determine the energy absorbed in normal and dry skin and was also useful for evaluating the effect of various treatments on skin softness. In a controlled environment, the data was reproducible.