A Comprehensive Modelling Approach for Bio-EDLC systems

The impetus to power wearable or miniaturized sensors has led to interest in the Double Layer Capacitor (DLC), a small footprint (ecologically and physically) energy storage device with the optimal benefits of high energy and power density. DLCs leverage complex double layer capacitances dictated by material and electrolyte-interface properties. Moreover, DLC operation is analogous to the sensing mechanism of our reported Organic Electrolyte Gated Field Effect Transistor (OEGFET) biosensor. In this work, we present a comprehensive modelling approach for Bio-electrolyte DLCs (Bio-EDLC) to accurately simulate them as electronic circuit components. This model can further be extended to predict the transient characteristics of our OEGFET Biosensors. We evaluate three common DLC equivalent models — the Classical Equivalent model, Zubieta model and Two-Branch model — to determine which most accurately captures the charge storage characteristics of our novel planar Bio-EDLC, containing a Carrageenan:PVA:Agarose (16:8:1) polymer-blended bioelectrolyte. We establish that Zubieta model most effectively captures the complex internal electrochemistry of these systems, predicting the transient characteristics with a 0.7% standard error (Classical Equivalent: 5.0%; Two-Branch: 1.7%).