Certain embodiments of the invention include medical materials and methods comprising a biodegradable hydrophilic hydrogel comprising dispersed lipophilic particles that comprise a therapeutic agent, wherein the lipophilic particles have a low water solubility in physiological saline at physiological temperature. In a strain gauge with moir\xe9 patterns, two foil layers are provided, a lower foil layer with a reference or static moir\xe9 pattern generated by the overlaying of a first pattern with parallel lines at a first fundamental frequency and a second pattern with parallel lines at a second fundamental frequency. According to the present invention, it is not needed an additional component such as the conventional plate spring and reflecting mirror, by using the reflecting film attached to the reflecting surface projected on a base plate instead of a horizontal synchronous mirror, in order to reflect the laser beams with the optical sensor.