Water vapor sorption by collagen and its application to humidity sensor.

Water vapor sorption on collagen, which was extracted from chicken legs, was studied. A piezoelectric crystal is used as a microbalance in the sorption experiments. Two kinds of the collagen samples, namely film-type and fiber-type samples, were used for the sorption experiments. Film-type sample was prepared by casting an acetic acid (pH2.8) solution of the purified collagen onto a quartz crystal, and fiber-type sample was prepared by casting a phthalic acid-buffered (pH4.0) solution in which the purified collagen was dispersed. The sorption amount for the film-type sample was about twice as that for the fiber-type sample. The sorption behavior was analyzed by the cluster function, Flory-Huggins equation, and BET equation. The collagen sample was suitable for the application to humidity sensor.