In this article, a double electrolyte double gate organic field-effect transistor (EDG-OFET) is proposed and numerically investigated for pH sensing in body fluids. The channel of the organic semiconductor (OSC) is depicted by Pentacene, while the gate electrode is created using a reference electrode placed in the electrolyte solution. A cavity of 30 μm length at the oxide/organic semiconductor (OSC) interface to enable controlled diffusion of biological molecules into the active channel region. A 30μm cavity located at the interface of the oxide and organic semiconductor (OSC) aims to support the regulated diffusion of biological molecules into the active channel region. The electrical aspects of the EDG-OFET are evaluated through a shift in diffusion percentage from 0% to 75%. Drain current sensitivity is evaluated as a function of molecular diffusion. For the first time, sensor thrift and response time have been calculated using a simulation of a pH sensor. The results show that increasing biomolecular diffusion from 25% to 75% leads to a significant reduction in sensitivity from 2.25 × 105 to 3.38 × 102. A sensitivity drop of approximately 98.84% is observed between 25% and 50% diffusion, followed by an additional reduction of about 87% from 50% to 75%. These findings highlight the critical role of diffusion in EDG-OFET performance, its potential for time-dependent pH monitoring in biofluid-based diagnostics.