This paper describes an electrochemical biosensor for molecules for personalized medicine including pH and temperature shift monitoring system. Electrochemical sensors based on the cytochromes P450 detect the large majority of drugs commonly used in pharmacological treatments. The same cytochrome detects different drugs at different electrochemical interface potentials. Therefore, the potential encodes the drug type meanwhile current encodes drug concentration. However, potential and current depend on pH variations that might occur in the patient sample. This paper presents evidence of these variations and proposes a novel design for multiplexing the bio-sensing with a new pH with temperature control system.