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Acid hydrolysis is a key chemical treatment process that can significantly improve the functional and structural properties of starch without altering its granular morphology. In this study, the effect of acid hydrolysis on the structural, thermal, and chemical properties of cassava starch was investigated using an optimum concentration of 2.2 M hydrochloric (HCl) acid with varying hydrolysis times (30, 60 and 90 min). The acid hydrolyzed cassava starch was characterized using X-ray diffractometry, 13C nuclear magnetic resonance (13C-NMR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. The results of XRD and 13C-NMR studies showed improved relative crystallinity for the films prepared from acid hydrolyzed starch. FTIR and TGA analyses revealed that the moisture absorbance of cassava starch decreased significantly due to acid hydrolysis. The acid hydrolyzed starch granules showed a 32% reduction of moisture content than the native starch granules. The thin films prepared from the acid hydrolyzed films exhibited a maximum of ~ 40% and 20% reduction of water absorption than the native cassava starch films after 2 h and 24 h. The acid hydrolysis significantly impacted the mechanical properties of the films. Enhanced tensile strengths were observed with increasing hydrolysis time, reaching a maximum tensile strength of 5.7 MPa. The acid hydrolyzed films displayed a 23% reduction of elongation compared to the native cassava starch films. Increased tensile strength, lower water absorption, biodegradability, non-toxicity, low cost, and good thermal stability make the acid hydrolyzed cassava starch beneficial for potential food packaging applications.

Background: Technology experts foresee that nanotechnology is the next industrial revolution and it has great potential to bring solutions to many challenges of global relevance in terms of a diverse range of applications. Efficiency-driven economies are transforming into innovation-driven economies where Intellectual Property (IP) plays a pivotal role in achieving a competitive advantage. Whereas industry analysts assert that IP roadblocks will be a severe detriment to the development of nanotechnology due to infringements and high-profile patent battles. Various authors have made a significant effort to analyse the implications of IP on nanotechnology but most of the published literature covers only the years 2000- 2010. Data and insights pertaining to recent developments are lagging behind. Therefore, the objective of this review was to explore cutting-edge empirical evidence towards emerging trends of Intellectual Property protection in nanotechnology, thereby to provide insights aimed at unleashing the full potential of nanotechnology innovation for socio-economic advantage. Materials and Methods: Patent information over the period 2000 to 2018 was collated and analysed to determine the latest trends. To gain a global perspective, nanotechnology patents issued by the United States Patent and Trademark Office (USPTO) and nanotechnology patents published in the ‘PatentScope’ of the World Intellectual Property Organization (WIPO) were surveyed along with literature in relation to nanotechnology commercialization and litigation. Results: Our study revealed that worldwide protection of Intellectual Property in nanotechnology has steadily been increasing year-on-year accounting 3.3 million patent applications filed in 2018 in which China and U.S. are dominating. The other main contributors are Japan, Germany Republic of Korea, France and U.K. Asia has emerged as the single region to file more than half of total filings for the first time thus shifting global IP landscape from Europe to Asia. Another notable finding is that there is a significant growth in trademark registration in many of the leading economies. Top five technology fields with high international patenting activity are computer technology, medical technology, digital communication, electrical machinery and pharmaceuticals where computer technology is dominating. More than 90% of the total patents are granted on materials, devices and processes developed as basic building blocks of nanotechnology at laboratory level which sound as more downstream innovations in the short-term. Amid the upward trends in nanotechnology patenting, newly emerging obstacles pose risks to innovation. A key finding of the present study is that the increasing trend of patent litigation almost follows the same path of patent grants indicating a positive correlation. A global prominence of middle-income and low-income countries in patent filing is yet to emerge which foreshadows an IP divide. Discussion: A secondary market for patent assets is pronounced with many new types of players leading to a high cost of patenting nanotechnology. These trends foreshadow a surge of patent filings in the years to come and the patent offices will be confronted with that ‘surge’ of patent applications of increased complexity and multidisciplinary nature.Patent offices with inadequate efficacy will ultimately produce lowquality patents along with a difficulty to enter into markets and will facilitate exploiting of the IP legal systems to extract rewards for infringement without contributing to innovation or social prosperity of nations. Conclusion: Insights and recommendations given in this paper will enable nanotechnology researchers, inventors, technopreneurs and investors to understand recent trends and global perspectives on implications of IP in nanotechnology and intensifying IP battle thereby to contemplate and succeed in their roadmaps towards leveraging on nanotechnology.

Rutin, a flavanol, has been demonstrating excellent antioxidant, anti-inflammatory, anti-diabetic, and anti-carcinogenic properties. However, bioavailability is low due to low stability, solubility, digestion, and absorption by the intestine. This study aims to encapsulate rutin with three types of carrier materials using three different techniques and evaluate their antioxidant activity and bioactivity retention under in vitro gastrointestinal and dialysis conditions. Results showed that the rutin encapsulated lipid carrier has the highest radical inhibition activity for all the digestive phases, the highest singlet oxygen scavenging activity after the gastric phase and the highest anti-inflammatory activity for the dialyzable fraction. The rutin content of encapsulated lipid carriers for all the digestive phases was significantly higher (P≤0.05) comparatively. Fourier Transform Infrared spectroscopy, Particle size analysis, and Scanning Electron micrographs showed that rutin encapsulated lipid carrier was 1.7 μm with a polydispersity index of 0.909 indicating micro-encapsulation with heterogeneous dispersion.

Eichhornia crassipes is considered the worst aquatic weed in the world as it has become a serious threat to the environment and biodiversity hence eco-friendly utilization of this hydrophyte is needed and important. Enhancement of agricultural production to cater for increased food demand is a global challenge which is aggravated by climate change and scarcity of water. Superabsorbent materials have been developed to improve water retention in soil but majority of superabsorbent are synthetic based and non-biodegradable. Therefore, this study is aimed at developing an eco-friendly superabsorbent from E. crassipes in a cost-effective manner and assess its efficacy on improved water retention in soil. E. crassipes was collected from tank nearby Faculty of Applied Sciences, Wayamba University of Sri Lanka and petiole was treated with potassium hydroxide (KOH) followed by microwave irradiation in which reaction conditions were optimized to obtain maximum water absorption and swelling capacity. Prepared superabsorbent was characterized using Fourier Transform Infrared Spectroscopy (FTIR), XRD and scanning electron microscopy (SEM) techniques. Efficacy of the superabsorbent on improved water retention was assessed using normal loam soil. The superabsorbent showed a maximum swelling index of 1276% at KOH concentration of 0.1 moles/l which is attributed to highly porous structure, presence of hydrophilic functional groups in cellulose and hemicellulose, increased number of surface hydrophilic functional groups during the KOH activation process and carboxymethyl cellulose created during microwave irradiation. Water absorption capacity of the superabsorbent is greatly influenced by KOH concentration, reaction time, microwave power and exposure time. Water retention studies in soil showed that superabsorbent has capacity to retain water for 27 days with a slow rate of water evaporation whereas soil samples without superabsorbent showed a high rate of water evaporation retaining water only for 15 days. Findings of this study disclose an innovative method for development of an eco-friendly superabsorbent from E. crassipes in a cost-effective manner excluding toxic chemical reagents which can be used for improved water retention in soil effectively for climate change resilient sustainable agriculture.

The health and environmental concerns of the usage of non-biodegradable plastics have driven efforts to explore replacing them with renewable polymers. Although starch is a vital renewable polymer, poor water resistivity and thermo-mechanical properties have limited its applications. Recently, starch/synthetic biodegradable polymer blends have captured greater attention to replace inert plastic materials; the question of ‘immiscibility’ arises during the blend preparation due to the mixing of hydrophilic starch with hydrophobic polymers. The immiscibility issue between starch and synthetic polymers impacts the water absorption, thermo-mechanical properties, and chemical stability demanded by various engineering applications. Numerous studies have been carried out to eliminate the immiscibility issues of the different components in the polymer blends while enhancing the thermo-mechanical properties. Incorporating compatibilizers into the blend mixtures has significantly reduced the particle sizes of the dispersed phase while improving the interfacial adhesion between the starch and synthetic biodegradable polymer, leading to fine and homogeneous structures. Thus, Significant improvements in thermo-mechanical and barrier properties and water resistance can be observed in the compatibilized blends. This review provides an extensive discussion on the compatibilization processes of starch and petroleum-based polymer blends.

Conventional rare and toxic materials still dominate the photodetector industry. Therefore, efficient photodetectors based on environmentally friendly and low-cost materials are a high priority area. Addressing this issue, an n-Cu 2 O/p-CuI heterojunction based photodetector was fabricated and characterised. The photodetector was synthesised via atmospheric pressure hydrothermal and drop cast deposition processes. The Cu 2 O/CuI heterojunction was structurally, morphologically and optically characterised using XRD, EDX, SEM, and UV – VIS, respectively. At zero bias, the photodetectors exhibited a high sensitivity of 2.355 × 10 5 and 7 × 10 3 for visible and UV light, respectively. The observed highest responsivity at 465 nm is 250 mA W −1 . Further, the device showed a 2 nA cm -2 dark current with a fast rising and falling time of 582 and 817 μs, respectively. The long term ageing study showed that photodetector has a lifetime of more than four years. These results reveal that n-Cu 2 O/p-CuI photodetector is a favourable approach for affordable, environmentally friendly and high-performance UV/Visible photoelectronic applications.

Thin films of ferric oxide (α-Fe2O3) doped with manganese were synthesized on fluorine-doped tin oxide (FTO) glass substrates using the doctor blade method. Iron acetate powder was annealed at 600°C to obtain the crystalline α-Fe2O3. Polyethylene glycol was used as the binder. Manganese mass concentration in α-Fe2O3 was changed from 3 to 10% in the doping process. All the thin film samples were subsequently annealed at 120°C for 2 h in air. Samples were characterized using X-ray diffraction (XRD), UV–visible spectroscopy, Fourier transform infrared (FTIR) and X-ray fluorescence (XRF). According to the XRD patterns, single phase of α-Fe2O3 was crystallized in all the samples. XRD patterns confirmed that the hematite phase of the samples does not vary with doping concentration. FTIR spectra confirmed the formation of the iron oxide bonds without any impurity phases. According to the UV–visible spectroscopy, the lowest bandgap of 1.82 eV could be obtained for the samples with 6% of manganese. XRF analysis was employed to confirm the doping concentration after synthesizing thin film samples. The gas sensitivity of pure α-Fe2O3 thin films was measured in 1000 ppm of acetone vapour, CO2 gas, ethanol vapour and ammonia gas by means of a Keithley 6400 sourcemeter AUTOLB at the room temperature. For pure α-Fe2O3 thin films, higher gas sensitivities of 46 and 49.2% were observed for CO2 gas and acetone vapour, respectively. The gas sensitivity of the doped α-Fe2O3 thin films was measured only in 1000 ppm CO2 gas. The α-Fe2O3 thin film doped with 6% manganese exhibited remarkable sensing performance of 70.1% at room temperature in CO2 gas.

The use of growth factors and stem cells as the core treating agents is one step into creating a biocompatible Solid Lipid Nano Particles (SLNP) for treatments. Apart from obtaining these growth factors and stem cells from the patients, using the bi-product of the extraction process which is the lipid of the patient for the production of the SLNP assures the final product to be biocompatible and of a unique structure. The use of autologous cells and proteins from the patients makes the entire process medically ethical and more viable for treatment procedures. This article, thus discusses on the experimental process of developing such SLNP and the introduction of the relevant medical contraption designed uniquely for the procedure inclusive of a specified membrane.

In the present biomedical field, most of the bioanalytical analyses depend on the electrochemical based systems. Nanomaterials are one of the key factors in enhancing the efficiency of analytical devices. Various nanomaterials such as metal NPs, metal oxide NPs, inorganic NPs, polymeric NPs, carbon-based, and polyoxometalates nanostructures can be seen in a variety of electrochemical analytical systems. Two-electrode, three-electrode, and multi-electrode-based miniaturized electrochemical analytical systems are popular in both research and commercially available systems. Properties of various nanostructures, and their involvement as surface functionalization material for label-free, and label-based ways in different biosensor applications have been discussed. Usage of various analytical methods such as potentiometry, voltammetry, amperometry, conductometry, coulometry, and impedimetric for detection, characterization, and quantification of nanostructure-based sensor systems, have been discussed. Further advantages of nanomaterials in biosensors and other electrodes in electrochemical analytical systems are also discussed. Compared to overall detection methods nanoparticle-based electrochemical analytical systems offer an approach to single molecular detection. By presenting theory to implementation, we hope this chapter provides a broad overview of usage and behavior of nanoparticles in electrochemical analytical systems, which may help readers understand and apply this phenomenon for future electrochemical-based biomedical analytical applications.

Ferrites are composite materials which are widely used in mature technologies like permanent magnets, circuitry, microwave devices and magnetic recording. Now a days the range of application expanded to different fields like photocatalysis, biosensors, bioimaging, gas sensors and many other fields. At least one metal cation included Fe3+ containing large class of oxides is the basic elements of ferrite and applied as powder form and films or ceramic bodies. The remarkable properties of hybrid nanocomposites of ferrite and graphene incorporated devices shows high performance in numerous applications in analytical medical equipment such as sensors, biosensors; electronic devices such as memory devices, semiconductor devices; energy devices such as solar cells, electrocatalytic and photocatalytic based chemical storage devices and many other fields.

Hydrogen energy is realized to be promising as a potential replacement for fossil fuels; it is expected to become a prominent source of energy in the foreseeable future. Therefore, straightforward and cost-effective methods of hydrogen production are urgently required and are considered the current state-of-the-art in the field. Accordingly, the strategy of hydrogen production is very important; it can be achieved through photocatalytic water splitting under irradiation of suitable light sources, where materials are key factors to efficiently conduct this process. In this direction, titanium dioxide/titania (TiO2) has been demonstrated to be an excellent photocatalytic semiconductor towards hydrogen production through water splitting. However, the wide band gap structure, faster carrier recombination and inadequate charge transfer characteristics of TiO2 photocatalysts greatly limit their efficiency and restrain their practical applications in the field. In this context, the size, morphology and chemical properties of TiO2 have been tailored through a range of modification strategies. Closer insights into these processes reveal that the key factors of these modifications essentially involve tuning the crystal structures and surface characteristics and, thereby, the energy structures of titania. Therefore, in this review, we focus on energy structure modifications of TiO2 through various strategies, such as (i) tuning of size and morphology, (ii) creating defect structures, (iii) elemental doping, (iv) composites and (v) surface decoration with metal nanoparticles and co-catalysts. The content of this review provides insight into understanding the energy structure of TiO2 that supports photocatalytic hydrogen generation and therefore endows it with prospects for real-time application in the field to achieve sustainable hydrogen production.

Starch is one of the most common biodegradable polymers found in nature, and it is widely utilized in the food and beverage, bioplastic industry, paper industry, textile, and biofuel industries. Starch has received significant attention due to its environmental benignity, easy fabrication, relative abundance, non-toxicity, and biodegradability. However, native starch cannot be directly used due to its poor thermo-mechanical properties and higher water absorptivity. Therefore, native starch needs to be modified before its use. Major starch modification techniques include genetic, enzymatic, physical, and chemical. Among those, chemical modification techniques are widely employed in industries. This review presents comprehensive coverage of chemical starch modification techniques and genetic, enzymatic, and physical methods developed over the past few years. In addition, the current applications of chemically modified starch in the fields of packaging, adhesives, pharmaceuticals, agriculture, superabsorbent and wastewater treatment have also been discussed.

p-CuI (band gap ≈ 3.1 eV) is sensitised with quantum dots (QDs) of Cu2O (band gap ≈ 2.0 eV) as a novel hybrid strategy to make photoelectrochemical cells. In which, p-CuI thin film was deposited by immersing a cleaned copper sheet into a solution containing I2 (10−2 M), KI (0.1 M), CuSO4 (10−3 M) to make Cu/p-CuI photoelectrodes. To fabricate Cu/p-CuI/Cu2O photoelectrodes, Cu/p-CuI photoelectrodes were boiled in a CuSO4 (10−2 M) solution at different time intervals. When gradually increases the boiling time until 5 min, the size of the p-CuI microcrystals decreases with the formation of Cu2O QDs on p-CuI microcrystals. When the boiling period exceeds 5 mins, Cu2O QDs convert gradually into micro-crystals and covering p-CuI thin film. Variations in the photocurrent quantum efficiency (Φ%) with the Cu2O amount fabricated on p-CuI thin layer were monitored. The photophysical and photochemical processes associated at Cu/p-CuI/Cu2O-electrolyte interface are presented to delineate the sensitisation of p-CuI wide band gap semiconductor with Cu2O QDs produced. Our recent explanation on the kinetics of the photocurrent generation by dye sensitised solar cells using CAN’s model equation Φ = AD0 – BD02, was used to describe the QD sensitisation of p-CuI by Cu2O QDs. It was experimentally confirmed that CAN’s constant ‘A’ relates with the photocurrent generation processes and the CAN’s constant ‘B’ associated with the processes in suppression of photocurrent generation. Material characterisation from Scanning Electron Microscopy (SEM), Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), UV absorption, photocurrent action spectra, and photoelectrochemical (PEC) measurements through I-V characteristics are presented to confirm the formation of Cu/CuI/Cu2O electrodes. A remarkable H2 generation was noticed in the presence of 0.025 M Na2SO4 solution, from the QDs sensitised photogenerated electrons at Cu/p-CuI/Cu2O-electrolyte interface. The mechanism of H2 generation is confirmed with the energy band positions of p-CuI and Cu2O QDs under visible light irradiation. Different H2 profiles are presented in detail with the size of QDs fabricated on p-CuI.

Miniaturized in-house high-performance sensors are mandatory for implementing the current needs efficiently. With the microsystems, electrode material is crucial to overcome the above immediate necessity. In this study, gold interdigitated electrode (AuIDE) was overlaid on the silicon (Si) substrate using conventional photolithography process and tested to be applicable as a chemical sensor between the pH range of 3 and 12. The AuIDE was physically characterized by low and high power microscopic and scanning electron microscopic imaging. Further, 3D nano profiler was used to analyze the development on the surface structure. The designed AuIDE has 4 μm consecutive gaps between 6 μm width IDE finger electrodes. The bare IDE was electrically characterized by I–V curves. This microsensor was also tested with different laboratory and commercially relevant solutions and revealed that the stability is in the pH range between 3 and 12. Comparative analysis of AuIDE sensor with commercially available pH meter revealed that AuIDE sensor has ± 0.1 tolerance. This study has demonstrated that chemical behavior of the electrode through pH calibration for further applications in the field of chemical sensors with amperometric approach.

E.coli O157:H7 is one of the harmful foodborne pathogenic disease causing bacterium which leads many illnesses and even deaths each year. IDT or IDE (Interdigitated Electrode) based biosensors usually use electrochemical behavior through impedometric detection. In this paper we describe a novel mechanism for E.coli O157:H7 ssDNA target detection via electrical behavior through E.coli O157:H7 probe and (3-Aminopropyl)triethoxysilane (APTES) functionalized Au IDE biosensor. Tween-20 was used as blocking the nonspecific binding on non-immobilized area of the E.coli ssDNA probes. Au IDE was fabricated on the Si substrate using CMOS and conventional photolithographic process. Fabricated Au IDE was physically characterized by using high power microscope (HPM) and scanning electron microscope (SEM). IDE electrode edges were characterized using 3D nano profiler. The E.coli O157:H7 ssDNA probes were used as the receptor to capture the specific target ssDNA and Au IDE was used as the transducer. I-V characteristics were performed for each functionalization step as bare Au IDE, silanization and immobilization. Well functionalized biosensor was hybridized with complementary, non-complementary and single base mismatch ssDNA to confirm the specificity. Sensitivity measurements were done using different concentrations of complementary ssDNA targets from 1fM to 10 µM. The sensitivity and limit of detection (LOD) of the biosensor are 14.3 mAM−1 and 0.8 fM respectively. It was confirmed that Au IDE biosensor shown here is capable to detect specific and low concentrated E.coli O157:H7 ssDNA targets successfully.

Interdigitated electrode (IDE) based electrical biosensors are promising in the medical application field. The aim of the research study is design, fabricate and characterize of low cost, high sensitive biosensor for medical applications. IDE pattern was designed using AutoCAD software with 1 μm finger gap. Fabrication process was done using conventional photolithography process and standard CMOS process. Fabricated electrode was physically characterized using SEM images, electrically validated through I–V measurements and chemically tested with different pH buffer solutions. Al IDE was well fabricated with 0.1 μm tolerance between design mask and fabricated IDEs. Electrical measurements confirmed that IDE was well fabricated without any shortage and results of similar IDE samples were confirmed that the repeatability of the device. The extremely small current variations in nano ampere range were quantitatively detected using extra small volume of 1 μl for different pH buffer solutions. It is confirmed that IDEs are sensitive in both alkali and hydroxyl ions medium.

This paper presents the dependency of SAR distribution in the human brain and eye on the shape, size, and electrical properties for different frequencies. Calculations were carried out using the Finite Difference Time Domain (FDTD) Method. The results indicate that the SAR distribution does not much depend on the shape and size but it depends mainly on the electrical properties of the tissues. There is a drop in the magnitude of the SAR in the brain when moving from a cubical model to the spherical model. There is a magnitude drop in the eye, when going from a spherical model to the cubical model. For both brain and eye, when the size is decreased, the volume is reduced and therefore the electromagnetic energy absorption goes up. The human eye at 2500 MHz was considered to observe how the electrical properties of the tissues affect the electromagnetic energy absorption in an organ. When relative permittivity is perturbed in small percentages with conductivity remaining unchanged; the value of the maximum SAR also changes by small values. However, both these cases, when the electrical properties are changed, the location of maximum SAR remains unchanged. It is exactly at the center of the eye.

In this study, two types of modified cassava starch samples (MCS and MWS) prepared from commercially available native cassava starch (NCS) and native cassava starch extracted using the wet method (NWS) were investigated for the removal of Pb(II) ions from aqueous solutions. MCS and MWS samples were synthesized under acidic conditions using Pluronic 123 as the structure-directing agent and tetraethylorthosilicate (TEOS) as the chemical modifying agent. Modified starch samples were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray Diffraction (XRD), and a nitrogen (N2) gas adsorption–desorption analyser. MCS and MWS showed enhanced thermal stabilities upon acid hydrolysis and chemical modification. The effects of contact time and initial Pb(II) concentration were studied through batch adsorption experiments. Adsorption kinetics followed the pseudo-second-order kinetic model. The equilibrium adsorption data were analysed and compared by the Langmuir and Freundlich adsorption models. The coefficient correlation (R2) was employed as a measure of the fit. The Langmuir model fitted well with equilibrium adsorption data, giving a maximum Pb(II) adsorption capacity of 370.37 and 294.12 mg/g for MWS and MCS, respectively. Modified samples exhibited a higher desorption efficiency of over 97%. This study demonstrated that modified starch could be utilized for Pb(II) removal from industrial wastewater.

A series of Nd-doped TiO2 with Nd content ranging from 1 to 5 at.% were synthesized by solid state technique and explored as a photoanode material in dye-sensitized solar cells (DSSCs). Incorporation of Nd3+ into TiO2 lattice resulted in more negative flat band potential for Nd-doped TiO2 than pure TiO2, as determined by impedance spectroscopy (Mott–Schottky plots), which is highly desirable to achieve higher Voc in DSSCs. In addition, Nd doping in TiO2 provided the opportunities to engender higher density of oxygen vacancies and bang gap narrowing in Nd-TiO2 photoanode, which collectively enhanced the optical properties of photoanode DSSC in terms of higher dye loading and light absorption respectively. A best efficiency of 6.17% was achieved with 4% Nd-doped titania, resulting in a remarkable increase in efficiency (102.3%) of the device over the undoped titania cells. Induction of intermediate bands, realignment of energy levels leading to a better electron injection, high sensitizer loading, efficient charge separation due to dopant and its impurity levels contribute favorably towards the superior performance of Nd doped TiO2 DSSC. Spectroscopy (EIS) measurements showed Nd doped TiO2 photoanode possessed higher charge recombination resistance and longer electron lifetime compared to DSSCs with undoped TiO2. Keywords: Nd doped TiO2, Negative flat band potential, Higher dye loading, Charge recombination, Dye-sensitized solar cell

Si is one of the most common, and prominent element in electronic field. In this research, Al based interdigitated electrical biosensors was prepared using Si as base material to detect Salmonella enterica typhi (S. typhi). The usage of the IDE sensors in the biosensor field is tremendous in these days because of the large number of comb structured finger electrodes gain high sensitivity. S. typhi is a very harmful food borne pathogen, makes typhoid disease which causes many deaths annually in worldwide. The AutoCAD software was used to design the chrome mask of IDE sensor. The fabrication process was done using conventional photolithography method. The fabricated Al-IDE, morphologically analyzed using SEM and further structurally characterized using EDX. The SEM depicted the well fabricated interdigitated electrode fingers and finger gaps are nearly equal to 50 µm and 1µm, respectively as designed dimensions. Silanization by APTES, immobilization with carboxylic functionalized S. typhi ssDNA probes and blocking with tween-20 were the major functionalization steps. The sensitivity measurements were done using different concentration of complementary targets and selectivity measurements were done using complementary, non-complementary and single base mismatch ssDNA samples. Each step was electrically characterized using Nyquist plot by impedance analyzer. Selectivity measurement confirmed, the tween-20 was important for the specificity of biosensor. The sensitivity measurements further verify that the biosensor is appropriate for detection of various concentrations from 1 fM to 1 µM of S. typhi targets.

Lab-on-a-chip (LOC) is becoming a dominant tool for point-of-care (POC) diagnostics in the medical field, in the recent years. Multi-disease analysis using single chip via delivery of fluid with the same condition of multiple transducers without contamination is the pathway of multi-channel microfluidic based LOCs. The LOC system was designed using SOLTDWORKS software. The microfluidic photomask was designed by using AutoCAD software to make chrome mask. The SU-8 negative photoresist was used for master mold preparation through a photolithography process. PDMS was used as a medium of the microfluidic. The low power microscope, high power microscope, and surface profilometer were used to morphologically characterize the microfluidic mold and the PDMS microfluidic. 3-in-l nano biosensor kit was attached with the microfluidic to produce Nano-Biolab-on-a-chip (NBLOC) device. The structural integrity of the system was observed by dropping food coloring dye through the inlet and collecting at the outlet.

Interdigitated electrode based electrical biosensors are prominent in biosensor field. The large number of finger electrodes as comb structure gain high sensitivity through electrical measurements. Listeria monocytogenes is a serious food borne pathogen based bacterium that can cause dangerous disease to human, some infection may result in death. In here, biosensor was prepared from 1μm gap Aluminum Interdigitated Electrode (Al IDE). Functionalization steps of the Al IDE to create biosensor was based on silanization by APTES, immobilization with Gold Nano particles (GNPs) mixed single stranded Listeria synthetic probe ssDNA with Au nano-particles and blocking with tween-20. Before and after functionalization the sensor was characterized morphologically using SEM images and structurally using EDX spectra. The functionalization steps were electrically characterized using current-voltage measurements. The selectivity of the biosensor with specific target was identified electrically using complementary, non-complementary and single base mismatch ssDNA targets. Blocking step with tween-20 was important to detect target specifically. The obtained variations in current indicate the varied concentrations of Listeria targets and it is confirmed that biosensor is suitable to detect different concentrations in the range from 10 fM to 10 μΜ.

Electrical properties of spin coated Zn2+ doped CuO films were investigated. The spin speed and deposition time period were varied to obtain uniform films with necessary thickness. Films were subsequently annealed in air to crystallize the phase of CuO. A liquid phase of Zn2+ and CuO was used as the initial solution in this sol-gel spin coating method. The doping concentration was varied up to 10%. Structural properties of thin films were investigated using XRD patterns. The dislocation density and strain were found to be 1.1 × 1013 lines/m2 and 0.0012, respectively. Peaks of Zn2+ were not noticed in XRD patterns. Photocurrent and photovoltage of films were measured using Metrohm Autolab in the electrolyte of KI. Photovoltaic properties varied with doping concentration. Highest photocurrent was observed for the sample with lowest band gap. Although the highest photocurrent of 11.15 μA cm−2 could be obtained at doping concentrations of 6% and 8%, the highest photovoltage of 0.12 V was observed at the doping concentration of 10%. Impedance was determined using Metrohm Autolab for illuminated and non-illuminated thin film samples. Three semicircles were observed in Nyquist plots indicating photoelectrochemical properties in the liquid junction photocell. Equivalent circuits found using Nyquist plots are consist of three RC parallel circuit elements. SEM was employed to find surface morphology and particles size of thin film samples. According to SEM micrographs, the average particle size of all the films is approximately 100 nm.

Copper oxide (CuO) thin films with photocurrent as high as 25 μA/cm2 were deposited on conductive glass substrates using d.c. reactive sputtering. This was the highest reported photocurrent for sputteredp- type copper oxide measured in the electrolyte KI. The photocurrent drastically increased up to 25 (μA/cm2 as the sputtering pressure and the substrate temperature were increased up to 8.5 mbar and 192°C, respectively. All the synthesized films contained single phase of CuO in this range of pressure and substrate temperature. Variation of the photocurrent, photovoltage, structure and absorbance with deposition conditions were studied in detail.

A low cost and simple chemical method of boiling copper plates in CuSO4 solution is used to prepare Cu2O layers. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES) and optical absorption have been used to characterise these layers. It has been found that the layers consist of Cu2O phase with a thickness of about 1.4 mum for 60 minutes boiling in CuSO4 solution. The largest grain sizes are in the order of 1 mum and the layers contain cubic Cu2O phases. The layers are n-type in electrical conduction and the optical band gap observed is 2.2 eV. (C) 2002 Elsevier Science Ltd. All rights reserved.

Dye sensitised photoelectrochemical (PEC) cells based on Cu/p-CuSCN/LB films have been studied with mixed Langmuir Blodgett (LB) films as the dye layer. The effects of mixed layers were investigated in detail by observing the changes of optical absorption and photocurrent in a PEC cell configuration. Enhancements in both optical absorption and photocurrent were found when a mixture of octadecyl methylviolet-C-18 (M-C-18) and dioctadecyl rhodamine (C-18-R-C-18) were deposited using the LB technique on p-CuSCN wide band gap semiconductor. The maximum photocurrent quantum efficiency of the PEC cell reached approximate to 36% in KI (10(-2) M)+I-2 (10(-4) M) electrolyte solution when mixed LB films were used as the dye layer. Photocurrent enhancement is believed to be the enhancement of light absorption of the dye layers due to the interlocking of M-C-18 between the double C-18 chains of rhodamine. (C) 2001 Elsevier Science Ltd. All rights reserved.

Composites of p type cuprous oxide (p-Cu2O) and reduced graphene oxide (rGO) were prepared by depositing an rGO layer on top of nano-sized Cu2O particles prepared on a Cu substrate. These synthesized composites help to enhance the photocurrent over that of bare Cu2O, which means rGO acts as an excellent electron acceptor to separate electrons from Cu2O particles. Here the p-Cu2O layer was fabricated using thermal oxidation and the rGO layer was fabricated using electrophoretic deposition (EPD). The samples thus fabricated were characterized using diffuse reflectance spectra, Fourier transmission infrared (FTIR) spectra, scanning electron microscopy (SEM) images, time development of the photocurrent of photoelectrochemical cells, and electrochemical impedance spectroscopy (EIS) measurements. H2 evolution was observed using a gas chromatograph system.

n-type cuprous oxide (n-Cu2O) has been shown to be an excellent material for fabricating low cost solar cells due to the optical band gap of ~2.0 eV. A substantial photocurrent enhancement of 80% was measured at the Cu/n-Cu2O-electrolyte interface in a photo-electrochemical cell with the introduction of a thin layer of p-type Ag2O between n-Cu2O layers. The enhancement in photocurrent is attributed to the creation of copious electron–hole pairs due to the introduction of a sub-monolayer narrow band gap (~1.5 eV) Ag2O. To study the structure-property and evidence for the presence of fabricated materials, characterization techniques like diffuse reflectance, XRD, EDX, FTIR and SEM have been used.

H2 evolution was observed for the first time from a photoelectrochemical cell using an n-type Cu2O photoelectrode under visible light irradiation. Three-electrode configuration was used in the photoelectrochemical cell to observe H2 evolution. AgCl/Ag calomel electrode and a platinum plate were used as the reference and counter electrodes, respectively. Fe2+/Fe3+ redox couple was used as the electrolyte. H2 evolution was visible on the platinum electrode in the photoelectrochemical cell.

A remarkable stability in the sharp photo-current peak at 570 nm was found when p-CuSCN semiconductor photocathode was sensitized with double-dye LB films of rhodamine-C 18 (R-C 18 ) monolayers and methylviolet-C 18 (M-C 18 ) monolayers. At first, M-C 18 four monolayers were deposited on p-CuSCN and then, R-C 18 four monolayers were deposited on M-C 18 monolayers to make an molecular arrangement on the semiconductor (LB-(R-C 18 (4)/M-C 18 (4))/p-CuSCN). Such a photo-cathode exhibited a remarkable stability of steady-state photo-current in (10 −2 M) KI+(10 −4 M) I 2 aqueous solution of pH=6.5, where the quantum efficiency reached was 45%, as estimated by correcting the dye absorption in the sharp photo-current peak at 570 nm. When four monolayers of M-C 18 and four monolayers of R-C 18 were separated with an arachidic acid LB films, sharp photo-current peak and its stability gradually decreased. This remarkable stability may be due to an efficient energy transfer process and an efficient charge separation caused by a strong interaction between the parallel electron-vibration planes of both M-C 18 and R-C 18 molecules.

A well cleaned copper plate with a thin Au layer deposited was heated in air to make hole transfer sites with p-Cu2O at 800 °C for 3 min. A transparent NiO layer was prepared on the surface of this device to make electron transfer sites on the surface. This heat-treated device, having 2 µm Au layers, exhibited a remarkably stable steady photocurrent and a higher photocurrent quantum efficiency in a KI(10-2 M) + I2(10-4 M) electrolyte solution when a thin transparent 0.05 µm NiO layer was deposited on the surface to screen the electrolyte. During the heating of the Au-deposited copper plate at 800 °C for 3 min, initially an alloy of Cu and Au was produced, then a thin homogeneous p-Cu2O film was formed on the alloy by oxidizing the migrated Cu atoms onto the upper surface of the alloy. Characteristics of the samples observed by means of XRD measurements and SEM micrographs, V-I characteristics, photocurrent action spectra, the variations of the photocurrent quantum efficiency with the deposited thickness of NiO and Au layers, photodegradation and improved chemical stability of the p-Cu2O photocathode and H2 evolution from water by the photocathode were investigated to explain the junction effects of the modified p-Cu2O with the Cu + Au alloy and NiO transparent film at the electrolyte interface. Here, the NiO layer and Au particles in the Au + Cu alloy efficiently act as the electron-transfer and hole-transfer sites, respectively.

n-Cu2O photoelectrodes are obtained by immersing a copper plate in a CuSO4(10−3 M) and HCl (10−3 M) solutions. Samples are characterized with XRD and SEM measurements. It is found that Cu2+ ions and the copper substrate are essential to obtain n-type photoresponses from Cu2O. Photocurrent action spectra are investigated with various Cu2O amounts formed on the copper substrate, made from two different methods. Photoluminescence (PL) measurements of the samples prepared by the two methods are examined. Time development of the photocurrent is investigated in KI(10−2 M)+I2 (10−4 M) and trisodium citrate solutions.

Colloidal p-CuI deposited on copper substrates is sensitized with a double-dye system, rhodamine iodide and crystal violet. Rhodamine iodide is deposited on colloidal p-CuI as the first dye before the second dye crystal violet is deposited on rhodamine iodide. A photocurrent quantum efficiency enhancement can be observed for the double-dye system in comparison with the bare dye-sensitized systems. Two peaks can be clearly observed in the photocurrent action spectrum of the double-dye system. Absorption spectra, fluorescence spectra, photocurrent action spectra and energy level diagrams are presented in order to explain the possible reasons for the photocurrent generation mechanisms of the two peaks ( 530 nm and 620 nm) in the double-dye photocurrent action spectrum.

Surface states on p-CuSCN are sensitized by aggregated crystal violet in addition to the cathodic sensitization process between semiconductor valence band and the excited monomeric dye molecules. Formation of surface states on bare p-CuSCN is confirmed by experimental results of photocurrent measurements, diffuse reflectance spectra and photoluminescence measurements. Photocurrent quantum efficiency obtained for the aggregated dyes sensitized the surface is 25% at λ=460 nm, and 14% for the monomeric dyes at λ=580 nm. From the variation of photocurrent quantum efficiency with surface concentration of crystal violet at various biased electrode potentials and diffuse reflectance spectra of dye coated p-CuSCN, it is found that the appearance of the sharp photocurrent quantum efficiency peak (λ=460 nm) is due to the sensitization process with the aggregated dye and that of the broad photocurrent quantum efficiency peak (λ=580 nm) is due to the sensitization process with the monomeric dye.

Surface states in p-type CuI thiocyanate (CuSCN) were detected from I−V characteristics, diffuse reflectance spectra, and photocurrent action spectra. The p-CuSCN films are sensitized by rhodamine with octadecyl-alkyl chain, and the sensitized photocurrent is observed with the visible light illumination. In spite of the surface states in p-CuSCN, the maximum photocurrent quantum efficiency (gfmax) at λ = 560 nm, in 1 × 10−4 M KI + I2 solution, pH = 6, reached ∼ 8.6%, where the surface dye concentration of photocathode Cu/p-CuSCN/Dye was 1.1 × 1014 molecules cm−2. Photocathodes were biased at −0.25 V versus AgCl/Ag to give a zero dark current. From the variation of φ values with the reduction potential of electron acceptors, the cathodic sensitization mechanism presented is further confirmed.