In my research work(2 month duration), I covered concepts to be used for developing paper based glucose sensors. The topics I studied include:-1. Debye Huckel Theory used to estimate non-ideality(activity coefficient) of solution: The theory assumes non-ideality only due to coulombic attraction and spherical and unpolarizable ions. Using Poisson Boltzmann Equation excess free energy is estimated which is used to calculate activity coefficient.2. Relation between conductivity and concentration: Relaxation and electrophoretic effect are the key causes of deviation from conductivity at infinite dilution(calculated by balancing viscous drag with electric force). The resultant of these effects along with viscous drag is used to derive Debye-Huckel-Onsager Equation. Qualitative study of model given by Fuoss-Onsager in 1957 which also onsidered cross-term of above effects and superimposed each effect to get total deviation in conductivity.3. Preparation of Graphene ink: Graphene preparation methods like Epitaxial growth on SiC, CVD using Hydrocarbons and substrate having low C solubility whose lattice matched with that of Graphene like Cu to produce high mobility graphene, Chemical Method- producing Graphene Oxide and then reducing to give reduced Graphene Oxide: produces lower conductivity graphene, and Direct sonication of graphite(small size graphene flakes resulting in more boundaries and hence higher resistivity)

Graphene is best dissolved in solvents having similar surface tension graphene like NMP, DMF and Cyclopropanol. But it can fairly dissolve in aquous solvents by adding detergents. Solvent Exchange is the method I liked the most as is gives good concentration of Graphene in non-toxic solvents(unlike NMP)4. Marcus Theory of Electron Transfer to first derive rate constant for outer sphere electron transfer and then extending it to heterogeneous electron transfer(electron transfer from electrode to electrolyte solution). The rate expression follows Boltzmann distribution with activation energy involving reorganizational(concerning solvent and vibration) enegry and gibb's free energy of reaction.5. Mediated Electron Transfer in Glucose-Oxidase enzyme which eliminates need of dissolved oxygen in blood to reoxidize glucose oxidase enzyme after it oxidizes glucose. Mediators like ferrocene derivatives and wired enzyme electrodes were studied(electrodes which are attached to redox active site in glucose oxidase using polymer molecules)