Dielectric properties of SrTiO3–Pt (platinum) composites prepared using conventional ceramic method were investigated. Dense complex ceramics were obtained without chemical reaction between SrTiO3 and Pt during sintering processes. The relative permittivity (εr) of SrTiO3 was increased by the addition of Pt particles nearly up to the percolation threshold of 27.8vol% as predicted using normalized percolation theory. The maximum εr of 2150 at 1MHz was obtained for the composite including 27vol% Pt due to the increased electric field around Pt particles. Using finite difference time domain method, the increase of electric field in the direction of applied electric field was confirmed visually in the vicinity of the embedded metal particles.

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An electrochemical capacitance immunosensor based on an interdigitated wave-shaped micro electrode array (IDWµE) for direct and label-free detection of C-reactive protein (CRP) was reported. A self-assembled monolayer (SAM) of dithiobis (succinimidyl propionate) (DTSP) was used to modify the electrode array for antibody immobilization. The SAM functionalized electrode array was characterized morphologically by atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDX). The nature of gold-sulfur interactions on SAM-treated electrode array was probed by X-ray photoelectron spectroscopy (XPS). The covalent linking of anti-CRP-antibodies onto the SAM modified electrode array was characterized morphologically through AFM, and electrochemically through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The application of phosphate-buffered saline (PBS) and human serum (HS) samples containing different concentrations of CRP in the electrode array caused changes in the electrode interfacial capacitance upon CRP binding. CRP concentrations in PBS and HS were determined quantitatively by measuring the change in capacitance (ΔC) through EIS. The electrode immobilized with anti-CRP-antibodies showed an increase in ΔC with the addition of CRP concentrations over a range of 0.01–10,000 ng mL−1. The electrode showed detection limits of 0.025 ng mL−1 and 0.23 ng mL−1 (S/N = 3) in PBS and HS, respectively. The biosensor showed a good reproducibility (relative standard deviation (RSD), 1.70%), repeatability (RSD, 1.95%), and adequate selectivity in presence of interferents towards CRP detection. The sensor also exhibited a significant storage stability of 2 weeks at 4 °C in 1× PBS.

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The microwave dielectric properties of the (1-x)MgTiO3–xSrTiO3 system have been investigated. The objective of the present work is to compensate for the negative temperature coefficient of the resonant frequency (τf) of MgTiO3 by addition of SrTiO3. The variation in microwave properties of the system significantly depends on the amount of SrTiO3 present, and they can be matched using mixing rules. With increasing x, the dielectric constant (ε r) increased and the quality factor (Q f) decreased. A ceramic sample with x=0.036 of SrTiO3, sintered at 1270°C for 2 h, and having a near-zero temperature coefficient of resonant frequency (τf) of -1.3 ppm/°C can be obtained.