Sensor pod body
An oval fit-check shell with ribbon slots, internal cavity, and a circular skin-side opening for a floating pad/plunger.
Industrial design
Jewelry outside. Test fixture inside.
The wearable has to maintain gentle, repeatable lateral contact while remaining visibly removable. Comfort, breakaway behavior, and RF repeatability are coupled mechanical requirements.
Placement principle
Start with a small contact pod against the lateral laryngeal area, not a hard element centered on the airway. Explore position systematically; anatomy varies. The pod should follow tissue with a soft pad while the textile band carries almost no structural load. A second decorative pendant may sit at the front without being the contact transducer.
Never optimize signal by simply tightening the band. If useful signal demands uncomfortable pressure, the transducer, pad, placement, or product concept has failed that configuration.
Contact stack
| Layer | Job | Failure to watch |
|---|---|---|
| Skin-safe removable cover | Hygiene and cleanability | Irritation, sweat retention, acoustic damping drift |
| Compliant pad | Conform to tissue and transmit vibration | Too soft: low coupling; too hard: discomfort and motion knock |
| Floating contact plunger | Spread force and isolate enclosure edge | Bottoming out, edge loading, rattling |
| Piezo/PVDF element | Convert strain/vibration to voltage | Lead stress, depolarization, cracking, cable microphonics |
| Pod body/cap | Locate parts and provide textile slots | Sharp seam, sweat ingress, detuning, resonance coloration |
Breakaway and mute
The production clasp should perform two independent functions with one visible action:
- Release mechanically under an appropriately validated load and by an intentional one-handed pull.
- Open the sensor path and force the tag into a measured non-recoverable state, for example by opening the sensor connection and shorting/detuning the resonator with a separate contact.
Do not choose a breakaway force from guesswork. Define use populations, hair/clothing snag cases, false-release tolerance, and applicable jewelry/lanyard requirements with a safety engineer; then test distributions after aging, sweat, cleaning, cold, heat, and manufacturing tolerance.
Supplied CAD
Sensor pod cap
A simple snap/adhesive development cover. It is not sealed and has not been validated for retention.
Pendant shell
A jewelry-scale oval shell sized to hold replaceable resonator coupons. It includes a front jewel recess and textile bail.
Generator
OpenSCAD is the authoritative parametric source. A dependency-free Python fallback generates deterministic faceted fit-check STLs.
Print and inspect
- Generate or download the three STL files.
- Print in a dimensionally stable material for bench fit only; no raw print surface should contact skin during a human evaluation.
- Measure the coupon cavity, cap fit, ribbon slots, and plunger clearance with calipers. Record printer, material, layer height, and shrink.
- Deburr, clean, and cover skin-facing surfaces. Inspect every edge before each session.
- Use the model only for short supervised placement studies. Production skin contact, cleaning, sealing, and biocompatibility require separate engineering.
P0 mechanical experiment
Use a balanced placement/pad experiment instead of adjusting by feel forever. Factors: lateral position, pad stiffness, pad thickness, contact area, band geometry, and posture. Responses: contact-to-room wearer SNR, other-speaker rejection, motion transient rate, comfort score, repositioning repeatability, and visible skin response after removal. Randomize order; include rest; stop on discomfort.
Materials questions before sale
- Skin-contact material characterization and supplier change control.
- Nickel release and restricted substances for metal findings.
- Sweat, cosmetics, sunscreen, hair product, cleaning, and UV aging.
- Water/sweat ingress without trapping moisture against skin.
- Textile fray, dye transfer, odor, and dimensional change.
- Magnets and medical implants: avoid unnecessary magnets; if used, assess and label appropriately.
- End-of-life separation of textile, electronics, and plated components.