Development of a Detection Algorithm for Use with Reflectance-Based, Real-Time Chemical Sensing

• Published in: Sensors (Basel, Switzerland) Vol. 16; no. 11; p. 1927
• Main Authors: Malanoski, Anthony P, Johnson, Brandy J, Erickson, Jeffrey S, Stenger, David A
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 16-11-2016; MDPI
• Subjects: algorithm; Algorithms; autonomous; chemical detector; Color sensitivity; colorimetric; Colorimetry; Indicators; Organic chemistry; Portable equipment; Real time; Reflectance; sensor; colorimetric; sensor; autonomous; chemical detector; algorithm
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s16111927

Here, we describe our efforts focused on development of an algorithm for identification of detection events in a real-time sensing application relying on reporting of color values using commercially available color sensing chips. The effort focuses on the identification of event occurrence, rather than target identification, and utilizes approaches suitable to onboard device incorporation to facilitate portable and autonomous use. The described algorithm first excludes electronic noise generated by the sensor system and determines response thresholds. This automatic adjustment provides the potential for use with device variations as well as accommodating differing indicator behaviors. Multiple signal channels (RGB) as well as multiple indicator array elements are combined for reporting of an event with a minimum of false responses. While the method reported was developed for use with paper-supported porphyrin and metalloporphyrin indicators, it should be equally applicable to other colorimetric indicators. Depending on device configurations, receiver operating characteristic (ROC) sensitivities of 1 could be obtained with specificities of 0.87 (threshold 160 ppb, ethanol).