Cardiac Device Manufacturing
Manufacturing Components for Wearable Stick-to-Skin Cardiac Monitoring Devices
Wearable cardiac monitoring patches — thin, flexible devices that adhere directly to the chest for days or weeks — have become essential for continuous ECG, arrhythmia detection, and remote patient monitoring. Producing these medical-grade wearables requires specialized materials and processes that balance strong skin adhesion, patient comfort, signal accuracy, and regulatory compliance.
Manufacturing Components for Wearable Stick-to-Skin Cardiac Monitoring Devices
Primary function: Keep the patch securely attached for 7–21 days while allowing the skin to breathe and minimizing irritation or allergic reactions. Common choices: Hydrocolloid, silicone, or acrylic pressure-sensitive adhesives (PSAs). Many manufacturers now use patterned or perforated adhesive coatings to boost moisture-vapor transmission rate (MVTR) and reduce the risk of medical-adhesive-related skin injury (MARSI).
Adhesive & bonding layers
- Pressure-sensitive adhesive (PSA) die-cuts / transfer tapes
- Materials: acrylic PSAs, silicone PSAs, rubber PSAs (medical grade).
- Thickness: 25–250 µm (1–10 mil).
- Processes: lamination, kiss-cut, through-cut, transfer coating.
- Use: seal microfluidic layers, form channels by selective bonding, tack for assembly.
- Thermoplastic welding films / thermal bond adhesives
- Materials: polyethylene, polypropylene, specialized thermoplastic films.
- Thickness: 25–200 µm.
- Processes: thermal lamination, impulse welding.
- Use: permanent seals for reaction chambers that require high-temp exposure.
- Double-sided tape with patterned release liners
- Use: rapid assembly, pre-registered adhesive patterns to control fluid paths.
Channel-defining & spacer films
- Patterned spacer adhesives (channel-forming die-cuts)
- Materials: acrylic adhesive on PET/film carriers, laser-cut PSA.
- Thickness: 25–500 µm depending on channel depth.
- Processes: die-cut, laser-cut, plotter cutting.
- Use: define channel geometry, create reaction chamber volumes.
- Embossable thermoplastic films for molded channels
- Materials: COC, COP, PC.
- Processes: embossing, hot-emboss die forming.
- Use: formed microchannels for precise fluid handling.
Membranes for filtration, venting, and metering
- Hydrophobic vent membranes (air venting / bubble trap)
- Materials: PTFE, ePTFE, PVDF with hydrophobic treatment.
- Pore sizes: 0.1–5 µm (application dependent).
- Processes: die-cut, adhesive-backed options.
- Use: allow air escape while blocking liquid; pressure relief vents.
- Hydrophilic membranes (wicking / flow control / capillary stop)
- Materials: nitrocellulose (lateral flow), cellulose, polyethersulfone (PES), hydrophilized PTFE.
- Pore sizes: 0.1–10 µm.
- Processes: precision die-cutting, overlamination.
- Use: capillary flow, reagent distribution, filtration.
- Filtration membranes (particle/virus filtering)
- Materials: PES, PVDF, cellulose acetate, nylon.
- Pore sizes: 0.02–5 µm.
- Use: remove particulates, pre-filter sample.
- Porous foam membranes (wicking / absorbent pads)
- Materials: PU foam, cellulose foam.
- Use: waste reservoirs, absorb excess reagent.
Valve, burst, and metering films
- Pressure-actuated valve membranes
- Materials: thin elastomers (TPU, PDMS), laminated films with cutouts.
- Thickness: 25–200 µm.
- Use: on-chip valves that open/close with pressure or vacuum.
- Burstable foil / peel-seal membranes (reagent isolation)
- Materials: aluminum foil laminates, metallized PET, multi-layer foil.
- Processes: die-cut, heat-seal, laser scoring.
- Use: isolate lyophilized reagents or reagents until use; scored weak points for controlled rupture.
- Capillary burst valves (hydrophobic patches on film)
- Materials: surface-treated PET/COC with hydrophobic coatings or patterned adhesives.
- Use: passive flow control via capillary pressure thresholds.
Reagent & storage films / seals
- Foil laminate seals (moisture/oxygen barrier)
- Materials: Al foil laminated with PET/LDPE; multi-layer barrier films.
- Processes: form-fill-seal, die-cut seals.
- Use: reagent pouch covers, lyophilized reagent pouches, long-term storage.
- Desiccant films / sachet foils
- Materials: laminated foil pouches, breathable desiccant-embedded films.
- Use: maintain dry environment for reagents.
- Transfer/spotting carriers for dried reagents (paper/film backing)
- Materials: glass fiber pads, porous membranes laminated to film.
- Use: hold lyophilized enzymes, primers, probes inside chamber.
Conductive & thermal films
- Printed conductive traces / thin-film heaters
- Materials: silver/graphene/sputtered metal traces on polyimide, PET, or COC.
- Processes: screen print, inkjet, sputter, flex circuit lamination.
- Use: on-chip heaters for PCR thermal cycling, temperature sensors, electrical contacts.
- Flexible printed circuit interposers (polyimide flex)
- Materials: polyimide with copper traces, laminated to PET.
- Use: connect chip electrodes to instrument, sense signals, apply voltage.
- Thermal interface films / heat-spreading foils
- Materials: graphite films, thin metal foils.
- Use: even heat distribution across reaction chambers.
Optical control & stray-light management
- Black/opaque films
- Materials: black PET, black COC, carbon-loaded films.
- Use: prevent optical cross-talk between wells and block stray light.
- Reflective films / metallized foils
- Materials: aluminized PET.
- Use: increase signal by reflecting excitation/emission.
- Anti-reflective / anti-glare coatings on detection windows
- Processes: coatings applied to films for better optical performance.
Surface-treated films & coatings
- Hydrophilic surface treatments (promote wetting)
- Methods: plasma, corona, chemical grafting, surfactant coatings.
- Use: control capillary flow, reduce air bubbles.
- Hydrophobic coatings / patterning
- Use: capillary stops, channel definition.
- Anti-fouling / PEG coatings
- Use: reduce nonspecific protein/DNA adsorption, improve assay sensitivity.
- Adhesion promotion layers
- Use: improve bonding between dissimilar plastics or adhesives.
Release liners & handling carriers
- Silicone-coated release liners (paper or film-backed)
- Use: protect PSA until assembly, register die-cuts for pick-and-place.
- Low-tack carrier films (transfer tapes)
- Use: temporary support of fragile microfluidic components during assembly.
Lidding & user interface films
- Peelable user-access films
- Materials: easy-peel laminates, scored foils with tamper-evident features.
- Use: sample ports, user-accessible reagent chambers.
- Labeled overlays / instruction films
- Materials: printable PET/PVC overlays, with tactile features.
- Use: labeling, user guidance, barcode placement.
Sterilization- & process-compatibility notes
- Gamma / EtO / E-beam compatibility: specify material compatibility up front (e.g., some PSAs yellow or lose adhesion under gamma).
- Autoclave: most polymer films warp; use only materials rated for steam if required.
- Shelf-life & packaging: barrier foils + desiccants often required for lyophilized reagents.
Typical converting processes used
- Die-cutting & kiss-cutting — precision cut shapes for PSAs, membranes.
- Laser cutting — tight tolerances, small features, no tooling.
- Lamination — roll-to-roll or sheet lamination to build stacks.
- Embossing / hot-emboss — create microchannels in thermoplastics.
- Printed electronics (screen/inkjet/sputter) — heaters, traces, electrodes.
- Thermal/ultrasonic/laser welding — permanent seals between thermoplastic layers.
- Plasma/corona treatment & coating — tuning surface energy.
- Punching & stamping — high-volume shapes.
Typical tolerances & specs to call out on drawings
- Channel depth tolerance: ±5–20 µm (depends on process).
- Die-cut hole positional tolerance: ±0.05–0.25 mm (depending on tool & material).
- Adhesive placement tolerance: ±0.2 mm typical for high-precision.
- Surface roughness / optical clarity: specify % haze, transmission.
- Pore size distribution (membranes): specify mean pore size ± SD.
- Biocompatibility: USP Class VI / ISO 10993 requirements if in contact with sample or tissue.
Example component→material→use quick mapping (short)
- PCR optical window → COC, 200 µm → fluorescence read.
- Channel spacer → PSA on PET, 100 µm die-cut → microchannel definition.
- Reagent foil seal → Al/PET/LDPE laminate → foil seal over reagent well.
- Hydrophobic vent → ePTFE membrane, 0.2 µm → air vent.
- Lyophilized reagent pad → glass-fiber pad laminated to substrate → dried enzyme spot.
- On-chip heater → printed silver on polyimide → rapid thermal cycling.
Substrate & Cover Films – These form the top and bottom structural layers of the microfluidic device.
Polycarbonate (PC) 125-500 µm
- Optically clear, rigid, low autofluorescence, good machinability.
- Common in thermally bonded chips; stable for analytical or diagnostic use.
Cyclo Olefin Polymer (COP) / Cyclo Olefin Copolymer (COC) 100–500 µm
- Exceptional optical clarity, low water absorption, excellent chemical resistance.
- Gold standard for optical biosensors, DNA analysis, and diagnostic cartridges.