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Skin, Cushion, Seal or Protect: Choosing Materials for a Wearable Patch
A wearable patch, a continuous-monitor housing or an on-body sensor is a small layered stack with several different material jobs: a skin-side adhesive that holds the device for a target wear window, a comfort cushion that conforms to the skin, a perimeter seal that closes the housing toward an ingress class, and an interior pad that protects the board. The jobs point at different families, microcellular polyurethane, medical cellular silicone (BISCO MS-80 / MS-96) and skin-contact adhesives, and confusing them costs either the wear time, the comfort or the seal.
This guide separates the layers, maps the families, and frames everything at the material level only.
The application problem: one patch, several material jobs
A wearable patch, a continuous-monitor housing or an on-body sensor is a small layered stack, and each layer does a different job. There is a skin-side adhesive that holds the device to the body for a target wear window, a comfort cushion that conforms to the skin and spreads load, a perimeter seal that closes the housing toward an ingress class, and an interior pad that protects the board and the connector.
Confusing these layers is the most common cause of a part that peels early, irritates the contact area, or fails the housing seal. This guide separates the jobs and maps each to a material family H-O Products converts.
- Skin-side attachment: a skin-contact pressure-sensitive adhesive (PSA) holds the device for the intended wear time and then releases. The adhesive family is evaluated by the material maker against ISO 10993-10 for sensitization and irritation as a material-level designation; the wear window depends on the chemistry and the backing.
- Comfort cushioning: a soft, conformable foam spreads load across the skin and takes up the gap between the housing and the body without a high contact pressure.
- Perimeter and device sealing: a resilient gasket closes the housing joint toward an ingress class under IEC 60529 so the electronics stay dry through wash and sweat exposure.
- Electronics protection: an interior pad cushions the PCB, the battery and the connector against drop and daily handling.
Why is choosing a skin-interface material challenging?
The layers pull in different directions. The skin adhesive wants enough tack to hold for the wear window but a clean, low-trauma release at the end, and a backing that breathes so moisture does not build up under an occlusive film. The comfort cushion wants softness and conformability, which is the opposite of the firmness a perimeter seal needs. The seal wants resilience and recovery across a sweat-and-wash environment, and the interior pad wants a controlled force-deflection curve at low closure force so it protects without pre-loading the housing.
A single material rarely satisfies all four, so the right design is usually a small kit of die-cut layers, each chosen for its own job, laminated and supplied on a release liner.
Recommended material families
Each job maps to a family H-O Products converts. A family is named on this page only where it is catalog-verified; grade-level values such as force-deflection, wear behavior and any material-level designation are confirmed against the manufacturer's current technical data sheet before specifying.
For the comfort cushion: microcellular polyurethane
PORON® Medical microcellular polyurethane holds a soft, conformable, relatively flat force-deflection curve and recovers without taking a fast set, characterized per ASTM D3574 with compression set per ASTM D395. That makes it the lead for a skin-side comfort pad and for gap take-up between the housing and the body at low contact pressure. Medical grades are offered with documentation aligned to USP Class VI and ISO 10993 by designation; confirm the grade and its documentation on the data sheet.
For the perimeter and device seal: medical cellular silicone (BISCO MS-80 / MS-96)
BISCO® MS-80 / MS-96 medical cellular silicone holds a resilient seal across a wide temperature span and resists the sweat-and-wash environment of an on-body device, which makes it the choice for the housing perimeter gasket. Cellular-silicone properties are characterized per ASTM D1056, and medical grades carry documentation aligned to USP Class VI and ISO 10993 by designation; confirm the type, class and any documentation on the grade data sheet.
For the skin-side attachment: skin-contact PSA
silicone-acrylic combination skin-contact adhesives and related acrylic skin-contact adhesives are converted as die-cut borders and full-coverage layers carrying a release liner. The adhesive family is selected for the wear window and the backing, and is evaluated by the material maker against ISO 10993-10 for sensitization and irritation as a material-level designation. Peel and tack are grade-specific and confirmed against the data sheet; the finished-device skin-contact assessment belongs to the device maker.
For interior electronics protection: thin microcellular polyurethane
A thin grade of the same microcellular and breathable foam family protects the PCB, the battery and the connector at low closure force, taking up tolerance gaps without pre-loading the housing. The grade and gauge follow from the available stack height and the protected component; confirm the curve on the data sheet.
Skin, Cushion, Seal or Protect: Layer-to-Material Direction Selector
A soft, conformable microcellular polyurethane spreads load across the skin and takes up the gap at low contact pressure; the grade and any material-level designation are confirmed on the data sheet.
Illustrative only; confirm against current material data and a drawing review. This selector returns a material family direction, not a grade, a wear time or a guaranteed value, and it makes no clinical or skin-safety claim. Wear behavior, force-deflection, sealing class and any ISO 10993-10 / USP Class VI documentation are confirmed on the manufacturer's current technical data sheet, and the finished-device skin-contact assessment belongs to the device maker.
Design and converting considerations
- Separate the skin side from the structure. Specify the skin PSA for wear time and breathability, and the device-bonding tape for structural hold; they are different families on the same part.
- The gasket is one element of the ingress class. The groove, the housing closure and the compressed gasket together reach a class under IEC 60529; the rating belongs to the tested housing. Send the joint detail with the target class.
- Cushion at low contact pressure. A skin cushion and an interior pad work without pre-loading the body or the housing; specify the gap, the tolerance and the available force so the curve can be matched.
- Process fit. These layers are die-cut, kiss-cut, laser or rotary cut, laminated and supplied adhesive-backed on liners, sized to the patch geometry and kitted for assembly.
- Documentation, not certification. A material-level ISO 10993-10 or USP Class VI designation belongs to the material maker; ask for it on the data sheet, and keep the finished-device file with the device maker.
Common failure modes
| Failure mode | Root cause | Material direction |
|---|---|---|
| Patch lifts before the wear window ends | Skin PSA chemistry or backing mismatched to the wear time and moisture load | Reselect the skin-contact PSA family for the wear window and a breathable backing; confirm peel on the data sheet |
| Moisture build-up under the patch | An occlusive film with no breathability over a long wear time | Move to a breathable backing or a more open construction; MVTR is grade-specific, confirm on the data sheet |
| High contact pressure at the cushion | A firm sealing grade used as a skin comfort pad | A soft, conformable microcellular polyurethane was the fit; keep the firm grade on the seal |
| Housing seal fails wash exposure | A commodity foam where sweat and wash govern | Medical cellular silicone (BISCO MS-80 / MS-96) holds the seal across the environment; the class belongs to the tested housing |
| Skin side and structure conflated | One adhesive specified for both the skin and the housing bond | Split the functions: skin PSA for wear, device-bonding tape for structural hold |
How H-O Products helps
H-O Products is a precision die-cut converter serving medical and clean-component programs. We convert microcellular polyurethane, medical cellular silicone (BISCO MS-80 / MS-96) and skin-contact adhesives into wearable and skin-interface cushions, perimeter seals, skin-side borders and interior pads, cut to your patch geometry and kitted for assembly. As an ISO 9001:2015 certified organization, we help you separate the layers, recommend a family and grade direction for each, and request the material-level documentation you need.
We do not produce the raw foam, silicone or adhesive, and we do not make the finished device; grade values and any ISO 10993-10 or USP Class VI documentation are confirmed against the manufacturer's current technical data sheet, and the finished-device biocompatibility assessment belongs to you.
Building a wearable or on-body device stack?
Tell us the layer at each location, the target wear window, the ingress class and any material-level documentation you need (ISO 10993-10, USP Class VI by designation). We will recommend a family and grade direction for each layer and convert samples on your patch geometry.
Samples typically ship in 3 to 5 business days for common die-cut configurations; standard production runs about two weeks; special orders are quoted to the job.
Family-owned in Winsted, Connecticut since 1971 · ISO 9001:2015 certified · OEMs worldwide send us a drawing — and get back their part.
Related reading
Frequently asked questions
What materials go into a medical wearable patch?
A wearable patch is usually a layered die-cut stack: a skin-contact pressure-sensitive adhesive that holds the device for the wear window, a soft microcellular polyurethane comfort cushion, a resilient medical cellular silicone (BISCO MS-80 / MS-96) perimeter seal that closes the housing toward an ingress class, and a thin interior pad that protects the board and connector. Each layer is a different material family selected for its own job.
H-O Products converts these families to your geometry; grade values and any material-level documentation are confirmed against the manufacturer's current technical data sheet.
What does USP Class VI or ISO 10993 mean on a wearable material?
USP Class VI and ISO 10993 are material-level designations the material maker evaluates and documents on the grade data sheet; ISO 10993-10 specifically covers sensitization and irritation evaluation for a skin-contact material. They describe the material, not a finished-device clearance. The device maker owns the finished-device biocompatibility assessment and regulatory file. H-O Products is a converter and names a family only where it is catalog-verified; ask for the material-level documentation on the data sheet.
Is the skin adhesive the same as the device-bonding tape?
No. The skin-side adhesive is a skin-contact PSA selected for the wear window, the backing breathability and a material-level ISO 10993-10 evaluation. The device-bonding tape joins the housing halves or mounts components and is selected for structural hold to the plastics. They are different families on the same part, so specify the skin side and the structural side separately.
Request a quote for your wearable or skin-interface part
Send H-O your drawing or describe the stack—engineering reviews every RFQ, recommends a family per layer, and converts samples on your geometry.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
References
- ISO 10993-10, Biological Evaluation of Medical Devices, Part 10: Tests for Skin Sensitization. International Organization for Standardization (material-level designation).
- ISO 10993-1, Biological Evaluation of Medical Devices, Part 1: Evaluation and Testing Within a Risk Management Process. International Organization for Standardization.
- USP Class VI, United States Pharmacopeia, Biological Reactivity Tests, In Vivo (material-level designation).
- ASTM D3574, Standard Test Methods for Flexible Cellular Materials: Slab, Bonded, and Molded Urethane Foams. ASTM International.
- ASTM D1056, Standard Specification for Flexible Cellular Materials: Sponge or Expanded Rubber. ASTM International.
- IEC 60529, Degrees of Protection Provided by Enclosures (IP Code). International Electrotechnical Commission.
- Manufacturer technical data sheets for the named material families (Rogers PORON Medical, BISCO medical silicone, skin-contact adhesive grades); grade-specific values and material-level documentation are confirmed on the maker's current TDS.
This article describes material families H-O Products converts and cites published standards by designation (ISO 10993-10 for sensitization and irritation evaluation, USP Class VI and ISO 10993 as material-level designations, ASTM D3574 and ASTM D395 for urethane force-deflection and compression set, ASTM E96 for water-vapor transmission, ASTM D3330 for peel adhesion). It makes no patient, clinical, therapeutic, healing or efficacy claim of any kind.
The material maker evaluates and documents a grade against these standards on its current technical data sheet; the device maker owns the finished-device biocompatibility assessment and regulatory file. H-O Products is a precision die-cut converter, not a raw-material producer and not a medical-device manufacturer; this is not, and does not imply, an ISO 13485 certification, an FDA device registration, a cleanroom certification or a biocompatibility certification.
The only certification claimed is ISO 9001:2015, which governs the converting process. Grade-specific values are confirmed against the manufacturer's current technical data sheet and an engineering drawing review. All parts are custom manufactured to order and minimum production run quantities apply.