We are very thankful to Yakima Maker Space for supplying us with the initial blueprint for the bracelet

Design Overview

The CalmaLink bracelet is a simple, accessible mindfulness device designed specifically for users without consistent internet access or smartphone availability. The bracelet guides users through breathwork exercises using gentle vibration patterns that indicate when to inhale, hold, and exhale - creating a tactile meditation experience without requiring visual attention.

Key Features:

  • Simple one-button activation

  • Programmable breathing pattern (4-7-8 pattern default)

  • 5-minute and 10-minute session options

  • Long battery life (3+ months of daily use)

  • Durable, water-resistant design

  • Optional solar charging supplement.

Circuit Design

Technical Notes:

  • The ATtiny85 microcontroller is programmed with the breathing pattern timing (e.g., 4-7-8 pattern)

  • Power consumption is optimized by putting the microcontroller to sleep between vibrations

  • The transistor acts as a switch to control the vibration motor

  • Battery life is extended by using low-power modes and minimal components

  • The optional solar cell can be integrated with a small charging circuit to supplement battery power

  • Different vibration patterns can be programmed for inhale (continuous vibration), hold (short pulses), and exhale (decreasing intensity)

Simple Circuit Description:

The circuit consists of:

1. A 3V coin cell battery (CR2032) as the main power source

2. A tactile momentary button for user input

3. An ATtiny85 microcontroller that controls the timing and patterns

4. A transistor (2N2222) that switches the vibration motor on/off

5. A 3V coin vibration motor for haptic feedback

6. Optional solar panel to extend battery life

Power Calculations:

Power consumption (estimated):

  • ATtiny85 sleep mode: ~0.1μA

  • ATtiny85 active: ~3mA

  • Vibration motor: ~80mA during vibration

  • Average consumption: ~5-10mA during use

  • CR2032 capacity: ~225mAh

  • Expected battery life: 20-40 hours of active use

Vibration Patterns

  • Inhale (4s): Continuous vibration

  • Hold (7s): Short pulse vibrations

  • Exhale (8s): Gradually decreasing intensity vibrations

Physical Design:

The device consists of a flexible silicone wristband with a small circular control unit that houses the electronics.

The control unit contains:

  • The button interface

  • Battery compartment for CR2032 battery

  • Optional small solar panel

  • Vibration motor

  • Circuit board with microcontroller

Additional Features

  • Adjustable band fits most wrist sizes

  • Water-resistant design (IPX5 rating)

  • Battery replacement requires simple tool (included)

  • Visual indicator for low battery (LED flash pattern)

  • Simple pictorial instructions that don't require language proficiency

  • Durable construction for harsh environments

Implementation Notes

Materials & Cost Considerations

Affordability: Total component cost should be under $15 (at scale) to make it accessible

Durability: Silicone band with sealed electronics to withstand daily use in rural environments

Low-tech manufacturing: Design can be assembled with minimal specialized equipment

Programming

The ATtiny85 microcontroller would be programmed with:

1. The 4-7-8 breathing pattern (or other customizable patterns)

2. Power management routines to maximize battery life

3. Button input detection for different modes

Development Pathway

1. Prototype Phase: Breadboard circuit with basic components

2. Testing Phase: Validate battery life and vibration patterns with users

3. Refinement: Optimize size and power consumption

4. Final Design: Create PCB layout and 3D printed enclosure