Million of orthopaedic implant procedures are carried yearly. Nonetheless, 40\% of the implants failed due to poor osseointegration and/or bacterial infection. Real-time monitoring of the physiological parameters at the tissue-implant interface can reveal important information about the onset and severity of infection allowing timely intervention. Thus, this work proposes a design methodology for a wireless pH measurement system capable to monitor pH levels at the implant surface. Iridium Oxide sensors are the most suitable devices due to their low drift, high sensitivity, high durability. The architecture of the device capable to transfer the pH measurements and power through NFC technology to an external device such as a smartphone or tablet is also described.