emerged as promising alternatives to commercial high-end ones. Being a high-performance, user-friendly device, the smartphone was the optimal platform to fabricate a simple optical sensing system as a signal transducer. In this study, we describe successful evaluation of glucose and lactate concentrations in cell culture media using the PAD in combination with a smartphone. By conjugating the PAD with a smartphone using a lightproof gadget, optical signal interference with the external light was optimized, making the assay suitable for real-time monitoring of glucose and lactate in the industry