< Return to Home

A_Rhythm

OVERVIEW

The A_Rhythm is a piece of wearable, biometric art designed to externally visualize a wearer’s internal, cyclical cardiac irregularity. It transforms raw pulse data into a dynamic light experience, making hidden physiological processes visible through LEDs.

INTENT

To make visible the invisible by translating a specific and personal real-world biological issue into a public experience. To help focus medical anxieties, by creating a tangible sign of internal physical distress and malfunction, helping "prove" it exists and needs treatment.

A photo showing the PPG sensor breadboard setup.

PPG Breadboard V2.0

A simulated waveform of raw PPG sensor data.

PPG Sensor Waveform

A flow chart illustrating the microcontroller logic.

MCU Logic Flow

Processing & Control

The ESP32 MCU uses a custom C++ algorithm, starting with a Moving Average Filter to clean the raw signal. It then calculates Heart Rate Variability (HRV) to differentiate normal rhythm from irregularities.

Rhythmic States (State Machine)

  • Baseline/Active: Normal rhythm/high-activity. Flowing, gentle wavefronts of light, with speed proportional to the current BPM.
  • Dissonant: Detects significant Heart Rate Variability (HRV) or cardiac irregularity. Triggers glitch patterns and rapid cycling of colors.

Output Mapping

The system calculates the Beat-to-Beat Interval and uses this data to drive the State Machine, delivering the current Rhythmic State to the LED array.

A sketch of the LED harness design on a body.

Harness Sketch

TECH STACK: Hardware

  • Sensor: High-sensitivity PPG Sensor (e.g., Max30101 variant)
  • Controller: ESP32 Microcontroller
  • Output: High-Density Addressable LEDs (WS2812B)
  • Power: Li-Po Battery, Logic Level Shifter
  • Tools: Pulse Oximeter (for testing)

TECH STACK: Software

Development in Arduino IDE (C++). Key techniques: Peak Detection, Signal Filtering, Heart-Rate-Analysis, Sinusoidal Easing Function, State Transition Handlers. Libraries include FastLED/NeoPixel and Sensor-Specific Library.

An ECG reading showing an irregular heartbeat.

Target ECG anomaly

A photo of various fabric and light strip samples.

Fabric & LED Tests

NEXT STEPS

- Hardware has been acquired.
- Schematic rough draft completed.
- Initial code prototype for signal processing and LED control is mapped.
- Further assembly is planned for over the holiday break.