# Investigation of a PID-Based Dynamic Illuminance Control System for Intelligent Neonatal Jaundice Phototherapy Using a Blue Light LED Array

## TL;DR

This paper presents a new LED-based phototherapy system with precise light control for treating neonatal jaundice.

## Contribution

A novel blue LED array with PID control for dynamic and precise neonatal phototherapy illumination is introduced.

## Key findings

- Blue light at 460 ± 10 nm matches bilirubin's absorption peak, optimizing phototherapy.
- LED radiation output was found to be largely linear, supporting linear control algorithms.
- PID control enabled stable and adjustable light output through electronic scanning.

## Abstract

Newborns are unable to reliably express changes in their physical condition due to their physiological immaturity and limited capacity for communication; therefore, continuous and systematic monitoring during phototherapy is essential to ensure timely detection of adverse responses and maintenance of therapeutic safety. This study extends our prior work, which introduced an indirect method for measuring light intensity to improve precision in monitoring newborn skin illumination. Light-emitting diode (LED) phototherapy has attracted considerable attention as an effective treatment for neonatal jaundice (NNJ). This study introduces an three-dimensional configuration of blue LEDs. An Arduino Mega 2560 microcontroller with pulse-width modulation (PWM) technology was employed to independently regulate the intensity of LED strips, enabling precise control of light output. The strips were mounted on an arc-shaped structure that can be adjusted mechanically and electronically through pre-programmed instructions embedded in the microcontroller. The results demonstrate that blue light at a wavelength of 460 ± 10 nm aligns with the peak absorption spectrum of bilirubin, thereby optimizing the efficacy of phototherapy for NNJ. Both observed absorption peaks were within the therapeutically effective range. Computer simulations confirmed that stable output contours can be achieved using rapid electronic scanning with a PID control algorithm to dynamically adjust the duty cycle. Experimental data showed that LED radiation output was largely linear. This supports the use of linear control algorithms and confirms the platform’s feasibility for future research.