There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

ZnO nanoparticles dispersed PVA–PVP blend matrix based high performance flexible nanodielectrics for multifunctional microelectronic devices

Breast cancer is the leading cause of death among females, early diagnostic methods with suitable treatments improve the 5-year survival rates significantly. Microwave breast imaging has been reported as the most potential to become the alternative or additional tool to the current gold standard X-ray mammography for detecting breast cancer. The microwave breast image quality is affected by the microwave sensor, sensor array, the number of sensors in the array and the size of the sensor. In fact, microwave sensor array and sensor play an important role in the microwave breast imaging system. Numerous microwave biosensors have been developed for biomedical applications, with particular focus on breast tumor detection. Compared to the conventional medical imaging and biosensor techniques, these microwave sensors not only enable better cancer detection and improve the image resolution, but also provide attractive features such as label-free detection. This paper aims to provide an overview of recent important achievements in microwave sensors for biomedical imaging applications, with particular focus on breast cancer detection. The electric properties of biological tissues at microwave spectrum, microwave imaging approaches, microwave biosensors, current challenges and future works are also discussed in the manuscript.

Microwave Sensors for Breast Cancer Detection

Biomarker-based cancer analysis has great potential to lead to a better understanding of disease at the molecular level and to improve early diagnosis and monitoring. Unlike conventional tissue biopsy, liquid biopsy allows the detection of a large variety of circulating biomarkers, such as microRNA (miRNA), exosomes, circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and proteins, in an easily accessible and minimally invasive way. In this review, we describe and evaluate the relevance and applicability of surface plasmon resonance (SPR) and localized SPR (LSPR)-based platforms for the detection of different classes of cancer biomarkers in liquid biopsy samples. Firstly, we critically discuss unsolved problems and issues in capturing and analyzing biomarkers. Secondly, we highlight current challenges which need to be resolved in applying SPR biosensors into clinical practice. Then, we mainly focus on applications of SPR-based platforms that process a patient sample aiming to detect and quantify biomarkers as a minimally invasive liquid biopsy tool for cancer patients appearing over the last 5 years. Finally, we describe the analytical performances of selected SPR biosensor assays and their significant advantages in terms of high sensitivity and specificity as well as accuracy and workflow simplicity.

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Surface Plasmon Resonance for Biomarker Detection: Advances in Non-invasive Cancer Diagnosis

This study reports the optical, structural, electrical and dielectric properties of Poly (vinyl alcohol) thin films membranes with embedded ZnO nanoparticles (PVA/ZnO) obtained by the solution casting method at low temperature of deposition. Fourier Transform Infrared spectra showed the characteristics peaks, which correspond to O–H and Zn–O bonds present in the hybrid material. The X-ray diffraction patterns indicated the presence of ZnO structure into the films. The composite material showed low absorbance and a wide band of gap energy from 5.5 to 5.83 eV. The surface morphology for the thin films of PVA/ZnO was studied by Atomic Force Microscopy and Scanning Electron Microscopy. The electrical properties of the membranes were also characterized by current-voltage characteristics and the DC conductivity showed Arrhenius behavior with values of activation energy from 0.62 to 0.78 eV and maximum conductivity at 2.4 × 10−12 S/cm. The dielectric properties of the nanocomposites were measured from low to high frequencies, and the results showed a high dielectric constant (e) in the order of 104 at low frequency and values from e ≈ 2000 to 100 in the range of 1 KHz–1 MHz respectively. The properties of PVA/ZnO such as the high permittivity and the low temperature of processing make it a suitable material for potential applications in the development of flexible electronic devices.

Polymeric Nanocomposites Membranes with High Permittivity Based on PVA-ZnO Nanoparticles for Potential Applications in Flexible Electronics.

Transparent nano composite PVA–TiO2 and PMMA–TiO2 thin films: Optical and dielectric properties

Nanostructured materials with plasmonic nanobiosensors for early cancer detection: A past and future prospect

Composite poly (vinyl alcohol)–aluminum oxide (PVA–Al2O3) thin films were successfully prepared on precleaned glass plates by dip coating method. The presence of metal–oxide (M–O) bond in the films was identified by Fourier transform infrared spectroscopy. The X-ray diffraction patterns revealed that both the as-grown and annealed films were predominately amorphous in nature. The scanning electron micrograph images showed that Al2O3 particles were distributed on the film surface and the size of the grains increased upon annealing. The energy dispersive X-ray spectroscopy analysis confirmed the presence of Al and O elements in the prepared films. The optical transmittance was found to be about 80 % for the as-grown film, whereas it was found to be increasing with the increase of annealing temperature and the band gap energy (3.74–3.78 eV) value decreased with the increase of annealing temperature. The frequency and temperature dependence of capacitance, dielectric constant, dielectric loss and AC conduction properties were investigated and the results showed enhanced dielectric properties. The obtained results indicated that the higher transmittance, wide band gap energy with high refractive index and high dielectric constant with low dielectric loss of the prepared composite PVA–Al2O3 thin films could be used as high-k layer in thin film transistors and optoelectronic devices.

Characterization of composite PVA–Al2O3 thin films prepared by dip coating method

Transparent with wide band gap InZnO nano thin film: Preparation and characterizations

New hybrid Poly (vinyl) alcohol (PVA)-InTiO transparent thin film was prepared by dip-coating method. Characteristic of MO vibrations (InO and TiO) were confirmed from Fourier transform infrared spectroscopy. The X-ray diffraction patterns revealed that the mixed phases of rutile TiO2 and cubic In2O3 were present in the hybrid film. Scanning electron microscopy images showed spherical shape mixed In2O3 and TiO2 nano particles embedded in the polymer matrix. The presence of elements such as In, Ti, and O are confirmed from energy dispersive X-ray spectroscopy. High transmittance (80%) and wide band gap energy (4.1 to 3.75 eV) values were observed from optical study. High dielectric constant (18 to 23) and low dielectric loss values were obtained from dielectric study. The observed amorphous nature, enhanced optical, and dielectric properties indicated that the hybrid thin film could be used as high-к layer in transparent thin film transistor and in opto-electronic device applications in near future. Copyright © 2015 John Wiley & Sons, Ltd.

Chandar Shekar Bellan

Papers

Transparent nano composite PVA–TiO2 and PMMA–TiO2 thin films: Optical and dielectric properties

Nanostructured materials with plasmonic nanobiosensors for early cancer detection: A past and future prospect

Characterization of composite PVA–Al2O3 thin films prepared by dip coating method

Transparent with wide band gap InZnO nano thin film: Preparation and characterizations

New transparent PVA‐InTiO hybrid thin films: influence of InTiO on the structure, morphology, optical, and dielectric properties