| The development and application of a portable, wireless fluorescence-based optical pH sensor system is presented. The design incorporates the MSP430 microcontroller as the control unit, an RF transceiver for wireless communication, digital filters and amplifiers, and a USB based communication module for data transmission. The pH sensor is based on ratiometric fluorescence detection from 6-methacryloyl-8-hydroxy-1,3-pyrene disulfonic acid (MA-HPDS) sensor patch. The ability of the sensor patch to detect the pH of the solution without physical contact makes the instrument inherently non-invasive. The sensor system also has the ability to transmit data wirelessly, enabling its use in processes that entail stringent temperature control and sterility. The use of the microcontroller makes the system a reliable, low-cost, and low-power device. The luminous intensity of the light source can be digitally controlled to maximize the sensitivity of the system. The sensor system is accurate and reversible over the pH range of 6-9 with an average response time of less than 3 minutes and has a detection limit of 0.05 pH. |
