SoundMat (10) Sensor Manufacturing
In SoundMat (5) Sensor Principles and Design we covered theory and layout. This chapter covers manufacturing.
Stack bottom to top:
- Board
- Concentric ring electrodes (Rings)
- Velostat (piezoresistive layer)
- Sector electrodes (Slices)
That is also build order.
1 Laser cutting overview#
Laser cutting focuses a high-energy beam on the material surface, melting/vaporizing/ablation in milliseconds. Two jobs: cut (through-cut) and etch (surface pattern).
Input is vector art (SVG, PDF, etc.) with colors/layers marking cut vs etch, plus power/speed per material.
Absorption depends on wavelength → pick the right machine. We used CO₂ and fiber lasers:
| CO₂ laser | Fiber laser | |
|---|---|---|
| Wavelength | ~10.6 μm (far IR) | ~1.06 μm (near IR) |
| Source | CO₂ discharge tube | Rare-earth-doped fiber |
| Good for | Non-metals: wood, acrylic, paper, fabric, leather | Metal, metal-coated materials |
| Poor for | Metal (low absorption) | Clear non-metals |
| Precision | Medium (larger spot) | High (smaller spot) |