Abstract
Bilirubin is a naturally occurring byproduct that is produced when red blood cells are broken down. Low levels of bilirubin in the blood do not present an issue, but often neonates are unable to properly dispose of bilirubin and develop hyperbilirubinemia (the excess buildup of bilirubin within the blood) which can cause serious complications. A major indication of hyperbilirubinemia is jaundice (the yellow discoloration of the skin and eyes). Hyperbilirubinemia can cause long term growth and developmental issues, like brain damage and even death. Therefore, it is imperative to keep an accurate track of blood serum bilirubin concentration in neonates, especially during the treatment of hyperbilirubinemia with photo (or light) therapy. Currently, the most accurate method of measuring blood serum bilirubin concentration levels is lab analysis. To obtain a blood sample for lab analysis, a heel-stick (slicing into a neonate’s heel) is performed. A heel-stick is an invasive and painful procedure that takes away precious amounts of blood from patients that do not have much to spare. There are existing non-invasive bilirubin monitors. However, these monitors provide inaccurate readings during phototherapy treatment. The project’s focus is on developing a flexible test-bed workstation to aid in the rapid development and prototyping of an inexpensive non-invasive, continuous bilirubin monitor that can provide useful readings even during the treatment of hyperbilirubinemia with phototherapy. The monitor will track bilirubin level in the blood by comparing the difference in the transmittance of two different wavelengths of light through an appendage. The monitor needs to rapidly cycle through blue, green, and no light periods and measure the photodetector output for each while making sure that the periods do not overlap with one another. The cycling of the light emitting diodes (LEDs) must occur fast enough to be able to accurately capture the cardiac cycle waveform shapes of transmittance for the quickest neonatal heartrate (200 beats per minute). The test-bed would be used to evaluate methods for controlling the light sources, measuring photodetector output, calculating transmittance values, and using these values to track blood bilirubin level. The designed test-bed showed promising results. It was able to control the rapid cycling of the two LEDs, without mutual interference, acquire and display versus time photodetector output samples at a rate higher than required, and track simulated blood serum bilirubin concentrations.