Entrain Network: The Node — Wearable Hardware Architecture

THE ENTRAIN NODE — WEARABLE HARDWARE DESIGN

FORM FACTOR: Adjustable headband, ~120g total

Each person in the network wears a single device — a headband that reads their brainwaves, gently entrains them toward the group frequency, and wirelessly syncs with every other node in range.

── COMPONENT 1: EEG SENSOR (Brain Reading) ──

Chip: ADS1299 analog front-end ($33 bulk)

• 8-channel, 24-bit resolution
• Designed specifically for EEG/biopotential
• 250 SPS sampling rate (more than sufficient)
• Signal-to-noise: >110dB CMRR

Electrodes: 4x dry silver/silver-chloride electrodes

• Positions: Fp1, Fp2 (frontal), T3, T4 (temporal)
• No gel required — spring-loaded for hair contact
• Impedance: <50 kΩ with dry contact

This matches the Muse 2 electrode placement but with research-grade 24-bit precision instead of consumer 12-bit.

── COMPONENT 2: ENTRAINMENT (Brain Writing) ──

Two simultaneous stimulation pathways:

a) BONE CONDUCTION TRANSDUCERS (2x, behind ears)

• Frequency range: 5-200Hz
• Delivers acoustic entrainment directly to cochlea
• Bypasses eardrums — leaves ears free
• Can deliver binaural beat (e.g., 110Hz left,

• Cost: $8 each, ~$16 pair

b) PEMF MICRO-COILS (2x, temporal positions)

• Pulsed electromagnetic field at 7.83Hz
• Field strength: 10 μT (same as commercial PEMF)
• Well below ICNIRP safety limits (200 μT)
• Small coils: 15mm diameter, 200 turns, 30 AWG
• Current: ~50mA pulsed (low power)
• Direct neural stimulation via induced electric field
• Cost: $3 each, ~$6 pair

── COMPONENT 3: PROCESSOR ──

ESP32-S3 dual-core microcontroller ($4-8)

- 240 MHz, 512 KB SRAM, 8 MB PSRAM

• WiFi 802.11 b/g/n + Bluetooth 5.0 (LE)
• Hardware floating-point for real-time FFT
• Ultra-low-power coprocessor for sleep modes
• Built-in USB-C for programming/charging
• SPI bus to ADS1299, I2S to bone conductors
• GPIO PWM to PEMF driver circuit

── COMPONENT 4: POWER ──

LiPo battery: 2000mAh, 3.7V

• Runtime: ~8-10 hours continuous
• Charge via USB-C, 2 hours to full
• TP4056 charge controller ($0.50)
• Battery weight: ~40g

── COMPONENT 5: FEEDBACK ──

3x RGB LEDs on forehead band:

• Left: YOUR brainwave state (color = frequency band)
• Center: SYNC status (breathing glow = coherent)
• Right: NETWORK status (nodes connected)

Haptic motor: gentle pulse when sync achieved

BILL OF MATERIALS — DIY NODE v1

ADS1299 breakout board ............ $40 ESP32-S3 DevKitC .................. $8 Dry electrodes (4x) + headband .... $35 Bone conduction transducers (2x) .. $16 PEMF coils + driver circuit ....... $12 LiPo battery 2000mAh ............. $8 TP4056 USB-C charger .............. $2 Custom PCB (JLCPCB, qty 5) ....... $15 RGB LEDs (3x) + haptic motor ...... $4 Enclosure (3D printed) ............ $10 Misc (wires, connectors, etc.) .... $10

TOTAL DIY COST: ~$160 per node

MASS PRODUCTION ESTIMATE (qty 1000+)

Custom integrated PCB ............. $25 ADS1299 + passives ................ $35 ESP32-S3module ................... $4 Electrodes + headband (injection) . $12 Transducers + coils ............... $15 Battery + charger ................. $6 Enclosure (injection molded) ...... $3 Assembly + testing ................ $10

MASS PRODUCTION COST: ~$110/unit

RETAIL PRICE: ~$250-350/unit

For comparison: