BWatch: A Non-invasive Blood Leakage Detection Device using Robust Reflectance-based Sensing

The insertion and removal of central venous catheter are associated with potentially fatal bleeding risk. This paper presents the design and development of BWatch, an effective stand-alone electronic device that continuously monitors the catheter insertion and extraction site for critical re-bleeding, that alerts medical staff immediately for proper care. The device employs novel non-invasive methods for blood detection. A capacitive circuit was designed to detect the presence of the moisture on the bandage. Exploiting the unique light absorption spectra of haemoglobin, the device subsequently illuminates and measures the absorbance of green light for accurate detection. Principal Component Analysis (PCA) was used to derive a suitable green LED light intensity and a single-value threshold from a triple-channel RGB light sensor for robust detection across medium. Finally, an experimental bench test was conducted in Changi General Hospital (CGH) and BWatch achieved 100% detection accuracy across 10 experimental run with real blood samples.