TY - JOUR A1 - Rogge, Christian A1 - Zinn, Steffen A1 - Prosposito, Paolo A1 - Francini, Roberto A1 - Foitzik, Andreas T1 - Transmitted light pH optode for small sample volumes JF - Journal of Sensors and Sensor Systems N2 - An innovative concept of a low-cost pH optode with working volumes of less than 150 µL is presented. The pH monitoring is based on the color changing effect of pH indicators. The optode includes an RGB color sensor patch TCS34725 from Adafruit, a controllable LED and reactor slides and is addressed by a self-written LabVIEW© software. Utilizing the hue value of the HSV color model, it is possible to analyze the color change of the indicator and estimate the pH value of the analyzed samples by exploiting sigmoidal fit models. Measurements carried out with phenol red and DMEM (Dulbecco's Modified Eagle's Medium) reported a standard error of calibration in the physiologic pH range (6.5–7.5) of ±0.04 pH units. Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-10093 SN - 2194-878X VL - 6 IS - 2 SP - 351 EP - 359 ER -