Procedures for reapplication study
ADHESION, BENDING, BEND
This was a 1‐day study in which the subjects remained at the clinic for approximately 2 h.The computerized cyberDERM 180° peel tester (Figure The computerized cyberDERM 180° peel tester uses a stepper motor attached to uniaxial lead screw to pull the stressing clamp at a constant rate of 5.0 + 0.2 mm/s. A calibrated Imada Digital Force Gauge records the resulting tension at least one sample per mm tape peeled.The OxySoftN and MaxN devices were run in a pairwise fashion, with one being assigned to the lateral side and the other to the medial side of the forearm according to the randomized treatment map, with the optical sensor region always positioned toward the wrist as shown in Figure Devices were tested in a pairwise fashion, with random assignment to lateral or medial location of the forearm. The optical sensor region was always positioned toward the wrist. Peel tests alternated between right and left forearms, with the first peel test always starting on the lateral site of the right forearm, until 18 peels tests were completed.A nontoxic marker was used to place fiducial marks on the subject's skin to ensure the device was placed parallel to the major axis of the forearm. The subject's arm was then positioned within the Peel Test Apparatus such that the test site surface was in plane with the horizontal path that the clamp would take during the run. A micro projector attached to the apparatus overlaid an image of the peel traverse to ensure proper alignment. Extreme care was also taken to have the subject always have his fingers properly placed and arm fully extended so that the tension across the skin surface remained reasonably constant during the entire series of peels for that individual.One caveat with the 180° peel test is that observed forces arise not only from detaching the adhesive device from the skin but also from the device bending back upon itself. Since both test devices consist of a flexible lead strip and a stiffer section with electrodes, the observed plot, as shown in Figure An example plot of the differences in the amount of force required to remove the tail and optical regions of the device during the 180° peel test, due to differences in stiffness along the deviceAs the adhesive under the optical region is the same as the adhesive on the tail for both devices, the increase in values seen in the optical region is not an increase in adhesion but rather an increase in force of removal due to the work required to bend the stiff components. Nevertheless, we do want to analyze this portion of the peel test because the effectiveness of the device depends upon the optical sensors being firmly attached to the skin. Thus, in addition to confirming visually that the sensor is still firmly attached to the skin, we also determined the work required to remove the optical region by using the Riemann left sum as an approximation of the area under the curve within the optical region.