Abstract: Apparatus for measuring the Young's modulus or the internal damping coefficient of skin, for example human skin, in vivo, comprises a rectangular frame of non-metallic material to be adhered by means of double-sided adhesive tape to the surface of skin to be tested, and a movable assembly also adherable to the skin surface by means of tape.The frame carries a vibration exciter in the form of a coil co-operating with a magnetic bead on the movable means, and also an opto-electronic movement sensor comprising an optical transmitter and receiver mounted next to one another on the frame and an optical reflector on the movable means for reflecting back to the light receiver the beam emitted by the light transmitter.

Abstract: The elastic properties of skin are measured by applying a torque to a disc placed in contact with a portion of the skin while holding a guard ring against skin around the region to define an annular skin sample to be stressed. Rotation of the disc is measured, and then the rotation is partially reversed and the torque-applying connection to the disc removed. The recovery rotation of the skin in the substantial absence of any applied torque is then measured.

Abstract: Young's modulus and/or the internal damping factor of an elastic material is obtained by subjecting an area of the material to a sustained vibration. The presence of the material being tested changes the resonance of a mechanical resonator and determination of the changed resonance peak enables the required elastic characteristics to be obtained. The sample may be subjected to varying tension during testing and can conveniently be vibrated by signals obtained from a variable frequency generator although, preferably, an electronic circuit for vibrating the resonator has a feed-back loop to operate as an electro-mechanical auto-oscillator.