890 research outputs found
Flexible electrochemical biochip array of patterned gold on silver inkjet printed polyimide
No full textFlexible electrodes for bio-electrochemical sensing were fabricated using state-of-the-art inkjet printing followed by two consecutive gold plating steps. Silver nanoparticle printed thin film (1.5μm thick) was sintered at 300°C for 30 minutes and used as seed for the electroless plating of gold (2μm). A further gold electroplating layer was then applied allowing good electrode properties overcoming the printed film roughness and porous morphology which the electroless plating step could not fully cover. The various layers as well as their composite were investigated using electrical, electrochemical and analytical techniques. Eventually, the final electrode was tested with a 3-electrodes setup in a chronoamperometric experiment to detect the Alkaline Phosphatase enzyme in presence of its substrate, ρ-Aminophenyl Phosphate. The electrodes demonstrated a sensitivity of 11.8μA/mM and a limit of detection of 0.9mM
Highly conductive copper film on inkjet-printed porous silver seed for flexible electronics
No full textNanoscale engineering of thin film morphology for efficient organic photovoltaic cells
No full textUniversity of Minnesota Ph.D. dissertation. July 2012. Major: Chemical Engineering. Advisor: Russell J. Holmes. 1 computer file (PDF); ix, 177 pages, appendices A-E.Organic photovoltaic cells (OPVs) have received significant industrial and academic interest in the last decade as a promising source of inexpensive renewable energy. However, further improvements in device performance and improved lifetimes are required for the commercialization of OPVs. This work is primarily focused on developing a novel device architecture to improve device performance and characterizing structure-property-performance relationships for OPVs. The excitonic nature of organic semiconductors necessitates the use of an electron donor-acceptor (D-A) heterojunction for efficient exciton dissociation and the generation of photocurrent. In many organic semiconductors, the optical absorption length is much larger than the exciton diffusion length. This trade-off between absorption and exciton diffusion is often overcome by increasing the area of the dissociating D-A interface using engineered film morphologies. This thesis presents an approach to maximize cell efficiency using a continuously graded D-A heterojunction. The graded heterojunction allows for an increase in the D-A interface area for an enhanced exciton diffusion efficiency, while also preserving the charge collection efficiency, leading to a significant improvement in device performance relative to that of optimized planar and uniformly mixed OPVs. In addition, this work correlates the optimized D-A composition gradient to the underlying film morphology and charge transport properties of uniform D-A mixtures. Subsequently, a new characterization technique to calculate the charge collection efficiency of OPVs is discussed. This technique is used to demonstrate the enhanced charge collection efficiency in graded heterojunctions relative to uniformly mixed heterojunctions. Afterwards, the properties of a new material and its potential as an electron donor material in OPVs are examined. Finally, an overview of the results and the ideas for future work are presented.Pandey, Richa. (2012). Nanoscale engineering of thin film morphology for efficient organic photovoltaic cells. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/156012
Directive speech acts in the New Testament
No full textDanuta Pytel-Pandey, WrocławThis article discusses the directive speech acts in the New Testament. The
author presents examples of such acts from the New Testament Scriptures, and
then carries out their pragmalinguistic [email protected]
Respiratory Patterns Recognition and Cough Detection Using Signals from Capacitive Touchpads in Smartphones Commonly Worn in Shirt Pockets
No full textThe timely identification of respiratory distress, often indicated by coughs, has become important for public health readiness and response to pandemics like COVID-19, SARS, and Influenza. Traditional methods of monitoring respiratory health, including hospitalization rates, doctor reports, and wearable sensors, have limitations in real-time reporting, extra costs, etc. With smartphones used by 66 out of every 100 persons, they are useful tools in various public health initiatives. Our project studies the use of capacitive touchpad sensors present in smartphones for monitoring respiratory patterns and distress. Specifically, this study examines how different touchpad scan patterns, orientations, and electrode spacings affect respiratory monitoring by detecting capacitive fluctuations. Our measurements with a commercial 5 by 6 element capacitive touchpad sensor array (0.8 cm pitch) worn on the chest or pocket registered fluctuations over the baseline due to cough-related chest surface movements. Furthermore, when the touchpad is placed on the chest or pocket, this method can also detect breathing rate by registering changes in capacitance over the baseline. Through this approach, we were able to measure very low capacitance values (0–100 pF), which are typically challenging to detect with conventional sensors. We also explored how varying electrode spacing impacts the fringing fields in the capacitive touchpad, as different configurations alter the depth and sensitivity of the capacitive field. This investigation allowed us to assess whether specific spacing setups could capture respiratory patterns deeper within body tissue, providing a non-invasive approach to respiratory health monitoring. This pioneering prototype demonstrates the potential for capacitive sensing to offer real-time, accessible respiratory monitoring using widely available smartphone technology
Spray coated bentonite/MWCNT composite enzymatic biosensor for uric acid detection
No full textBiosensors are widely used in healthcare and diagnostics, offering rapid and reliable detection of biological analytes. This study presents the development of an enzymatic uric acid (UA) biosensor based on a nanocomposite of bentonite (BT) and multi-walled carbon nanotubes (MWCNTs) fabricated via spray coating. The composite utilizes the high conductivity and surface area of MWCNTs along with the ion-exchange capacity and antifouling properties of BT to improve both electron transfer and long-term stability. Uricase (UOX) was immobilized on the BT/MWCNTs modified electrode using glutaraldehyde (GA) crosslinking, forming a stable enzyme matrix with strong adhesion and reduced leaching. The fabricated BT/MWCNT/GA/UOX biosensor was systematically characterized through morphological, chemical, and electrochemical analyses. Optimizing spray parameters enabled uniform film deposition and consistent surface roughness, thereby improving reproducibility across electrodes. The biosensor exhibited a broad linear detection range, high sensitivity, and a low detection limit of 5.31 µM in phosphate buffer, outperforming the control sensors prepared with BT-only and MWCNT-only films. Excellent selectivity was demonstrated against common interferents such as ascorbic acid and dopamine. The proposed sensor also exhibited good antifouling ability and was applicable to hydrodynamic conditions. Stability studies indicated that after 60 days of storage at 4 °C, the biosensor retained 92% of its initial response, showing minimal signal drift and structural degradation. Furthermore, real-sample validation using spiked human serum demonstrated reliable recovery (92.2–110.8%) and strong correlation (R² = 0.997) with the standard calibration, confirming the biosensor’s clinical applicability. These results confirm the mechanical, electrochemical, and operational robustness of the BT/MWCNT-based biosensor platform and suggest its strong potential for future integration into point-of-care (POC) diagnostic systems for UA and related metabolites
Similarities between 2D and 3D convection for large Prandtl number
No full textUsing direct numerical simulations of Rayleigh-B\'enard convection (RBC), we perform a comparative study of the spectra and fluxes of energy and entropy for large and infinite Prandtl numbers in two (2D) and three (3D) dimensions. We observe close similarities between the 2D and 3D RBC, in particular the kinetic energy spectrum , and the entropy spectrum exhibits a dual branch with a dominant spectrum. We showed that the dominant Fourier modes in the 2D and 3D flows are very close
Evaluation and analysis of impact of subsidies on small scale renewable energy technologies dissemination: a case study of Nepal
No full textThe report has analysed the status of rural electrification using renewable energy technologies (RETs) and the current subsidy delivery modality of RETs in Nepal. As the Government of Nepal is subsidizing small scale renewable energy projects, it is important to evaluate and analyse the programme to make sure that a programme is running in an effective and efficient way while reaching the target group.
During the course of the research, primary information collected from the field has been compiled using appropriate tools/software (such as MS Office) and analyzed. Different sets of questionnaires were prepared, targeting different personnel ranging from the users’ level to the government policy level. The field survey methods include field observations of RETs installations and operations along with interviews with selected users on a random sampling basis to identify barriers to subsidy delivery and possible measures to overcome these barriers; to determine user satisfaction level and time period for subsidy delivery mechanisms.
The report started with the country background information and the rationale behind the study. This is followed by the literature review and information on the current status of small scale RETs in the country. Next it deals with the organizational structure and current subsidy delivery modality of RETs in the country. The evaluation of the effectiveness of the subsidy with the current subsidy delivery modality has been analyzed based on six parameters; Targets and Achievements, Impact of RETs, Subsidy Delivery System Efficiency, Transparency, Sustainability and Effectiveness.
The research shows that the subsidized government program has been successful in achieving its goal to provide basic energy services in rural areas through RETs in terms of its quantitative target. Although the subsidized program is successful in electrifying the rural communities via RETs, the poorest of the poor families are still excluded from the subsidy. The program seems to benefit more the rich and upper middle class families rather than the poor families for which the subsidy was intended. The high capital cost and long subsidy delivery process are the main important reasons for this failure. The author has proposed a new modality which might overcome the time barriers and bureaucratic process in the subsidy delivery mechanism and will decrease the lead time. This will in turn help to reduce the operational cost of the private companies and will encourage more players to enter the market, increase competition and result in lower system costs.
After identifying gaps in the current subsidy delivery modality, the project report ends with the recommendation of a new modality improving the current modality and filling the gaps identified. As this study has some limitations, as described in chapter one, the scope of further works has been listed at the end
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