Capturing skin properties from dynamic mechanical analyses.
OBJECTIVE
Existing skin mechanical testing devices focus on measuring skin elasticity and are not tailored to assess the dynamic behavior of skin. Additionally, the mathematical techniques used in existing devices are often not optimal.


METHODS
A new dynamic mechanical device that measures the linear dynamics of skin was developed and tested. The mechanical properties of skin were evaluated in experiments in which stiffness and damping parameters were measured (i) at different locations on the arm and hand, (ii) when stratum corneum hydration was varied by controlled changes in environmental humidity, and (iii) following the application of film-forming polymers. Parallel measurements were made with the Cutometer so that the two devices could be compared.


RESULTS
The findings revealed that reliable and valid measurements of skin mechanical properties can be obtained from the device. The stiffness of the skin was shown to vary significantly as a function of skin site, changes in stratum corneum hydration and following application of the polymer films. Changes in the damping parameter were less consistently associated with varying the condition of the skin.


CONCLUSIONS
The high reliability and speed of measurement make this device and analytic procedure an attractive option for testing skin mechanics.
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Erika
E
Sandford
Yi
Y
Chen
Ian
I
Hunter
Greg
G
Hillebrand
Lynette
L
Jones
D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D001834:Body Water / Q000378:metabolism; D003879:Dermatologic Agents / Q000008:administration & dosage; D004548:Elasticity / Q000502:physiology; D054459:Elasticity Imaging Techniques / Q000295:instrumentation* / Q000379:methods*; D004817:Epidermis / Q000378:metabolism / Q000502:physiology*; D004867:Equipment Design; D005260:Female; D006801:Humans; D006813:Humidity; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011108:Polymers / Q000008:administration & dosage; D012879:Skin Physiological Phenomena; D013396:Suction / Q000295:instrumentation / Q000379:methods; D014783:Viscosity; D055815:Young Adult
D003879:Dermatologic Agents; D011108:Polymers