Karolis Petrauskas

Modelling carbon nanotubes-based mediatorless biosensor.

This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate.

Computational Modeling of Mediator Oxidation by Oxygen in an Amperometric Glucose Biosensor

In this paper, an amperometric glucose biosensor is modeled numerically. The model is based on non-stationary reaction-diffusion type equations. The model consists of four layers. An enzyme layer lies directly on a working electrode surface. The enzyme layer is attached to an electrode by a polyvinyl alcohol (PVA) coated terylene membrane. This membrane is modeled as a PVA layer and a terylene layer, which have different diffusivities. The fourth layer of the model is the diffusion layer, which is modeled using the Nernst approach. The system of partial differential equations is solved numerically using the finite difference technique. The operation of the biosensor was analyzed computationally with special emphasis on the biosensor response sensitivity to oxygen when the experiment was carried out in aerobic conditions. Particularly, numerical experiments show that the overall biosensor response sensitivity to oxygen is insignificant. The simulation results qualitatively explain and confirm the experimentally observed biosensor behavior.

One-Dimensional Modelling Of A Carbon Nanotube-Based Biosensor.

This paper presents a one-dimensional-in-space mathematical model of an amperometric biosensor based on a carbon nanotube electrode deposited on a perforated membrane. The developed model is based on nonlinear reaction-diffusion equations. The conditions at which the one-dimensional mathematical model can be applied to an accurate simulation of the biosensor response are investigated. The accuracy of the response simulated by using one-dimensional model is evaluated by the response simulated by the corresponding two-dimensional model. The mathematical model and the numerical solution are also validated by an experimental data. The obtained agreement between the simulation results and experimental data is admissible for different configurations of the biosensor operation. The numerical simulation was carried out using the finite difference technique.

Asynchronous Client-Side Coordination of Cluster Service Sessions

A system-to-system communication involving stateful sessions between a clustered service provider and a service consumer is investigated in this paper. An algorithm allowing to decrease a number of calls to failed provider nodes is proposed. It is designed for a clustered client and is based on an asynchronous communication. A formal specification of the algorithm is formulated in the TLA\(^+\) language and was used to investigate the correctness of the algorithm.

Amperometric Urea Sensor

The prototype of amperometric biosensor for urea determination was designed. The enzyme electrode, made of a specially developed modified graphite (MG) paste, was produced by covering the electrode surface with adjustable membrane containing immobilized urease from Canavalia ensiformis (E.C. 3.5.1.5.). Simple methodology of urea determination in real time has been proposed. The experimental study and the mathematical model of the biosensor action have been performed.