Moisture Vapor Transport Channels for the Improved Attachment of a Medical Device to the Human Body

Abstract

Attachment of a small, medical device to the human body for an extended period of time in an ambulatory setting requires the careful consideration of the physical form of the device and the physiological constraints limiting the time a device will stay on the skin. Factors such as the size of the device, the area of the device available for attachment to the skin, and the occlusive nature of the materials in the device are likely to affect adhesion. Here, plastic acrylic disks, 25 mm in diameter, containing a crisscross pattern of air-filled channels were tested on the forearm and abdomen using a moderately aggressive, unsupported, pressure-sensitive transfer adhesive in a pilot human clinical study. After vigorous exercise, droplets of moisture were observed in the channels followed by evaporation of the droplets over time. Disks without channels remained attached to the skin for about a day and a half, while disks containing 450 microm deep channels remained on the skin about three times longer. Little difference was found when the channel-to-channel spacing was increased from 1.3 to 1.6 mm, however 230 microm deep channels were less effective than 450 microm deep channels. Overall, the moisture vapor transport channels appear capable of reducing the moisture content of the outermost stratum corneum layer of the skin, increasing the strength of the stratum corneum, and increasing the time a device remains attached to the skin. The median trial-to-trial relative standard deviation of 45% observed in the pilot study can be used to design appropriately powered studies for the comparison of different device designs.

In vitro evaluation of skin adhesives during perspiration

“…This loss of adhesion was speculated to be caused by moisture at the interface, where the presence of free water could perturb the skin-adhesive interactions or cause a change in skin surface energy through hydration [10][11][12]. Regardless of the failure mechanism, it has become widely accepted that the removal of moisture from the skin-adhesive interface is vital for retaining adhesion during perspiration [10][11][12][13][14][15].…”

UV-crosslinkable acrylic pressure-sensitive adhesives for industrial application

“…Solvent-borne acrylic PSAs offer several advantages, such as excellent aging characteristics and resistance to elevated temperatures and plasticizers, exceptional optical clarity due to the polymer compatibility and non-yellowing. They also have the highest balance of adhesion and cohesion and an excellent water resistance [4].…”

Effect of epoxidation and surface modification on backing-required properties of peroxide prevulcanized natural rubber–based films

“…Moreover, Cunningham and Lowery showed that the transportation of moisture vapor affected the adhesion of medical device to the human skin. 2 The acrylic plastic disks with air-filled channels remained on the skin three times longer than the disks without the channels because of better water vapor transport. Additional interested property of backing layer is Young's modulus.…”

“…The properties of backing materials have influence on drug delivery profile, adhesion of the patch to skin, wear ability and skin irritation. 1,2 The backing layer can be classified into occlusive and nonocclusive types. The backing layer that has a water vapor transmission rate (WVTR) less than 26 g/m 2 /day is considered to be occlusive.…”

“…7 –9 Published articles attributed to the backing films based on natural rubber (NR) are very limited. Elastomeric materials, including NR and NR blended with polyolefins, were mentiond as backing materials in the patent of Venkatraman et al 10 They specified the WVTR and the Young’s modulus in a range of 2.4–480 g/m 2 /day and 0.001–100 MPa, respectively. Among polymers that are possibly useful for transdermal patches reviewed by Sukibayashi and Morimoto, 11 NR was included as a base with adhesive without providing information related to backing-required properties.…”