Matching Items (6)

128654-Thumbnail Image.png

Substrate and Passivation Techniques for Flexible Amorphous Silicon-Based X-ray Detectors

Description

Flexible active matrix display technology has been adapted to create new flexible photo-sensing electronic devices, including flexible X-ray detectors. Monolithic integration of amorphous silicon (a-Si) PIN photodiodes on a flexible

Flexible active matrix display technology has been adapted to create new flexible photo-sensing electronic devices, including flexible X-ray detectors. Monolithic integration of amorphous silicon (a-Si) PIN photodiodes on a flexible substrate poses significant challenges associated with the intrinsic film stress of amorphous silicon. This paper examines how altering device structuring and diode passivation layers can greatly improve the electrical performance and the mechanical reliability of the device, thereby eliminating one of the major weaknesses of a-Si PIN diodes in comparison to alternative photodetector technology, such as organic bulk heterojunction photodiodes and amorphous selenium. A dark current of 0.5 pA/mm[superscript 2] and photodiode quantum efficiency of 74% are possible with a pixelated diode structure with a silicon nitride/SU-8 bilayer passivation structure on a 20 µm-thick polyimide substrate.

Contributors

Agent

Created

Date Created
  • 2016-07-26

134918-Thumbnail Image.png

The Benefits and Application of Statistical Process Control in a Manufacturing Environment

Description

Statistical process control (SPC) is an important quality application that is used throughout industry and is composed of control charts. Most often, it is applied in the final stages of

Statistical process control (SPC) is an important quality application that is used throughout industry and is composed of control charts. Most often, it is applied in the final stages of product manufacturing. However it would be beneficial to apply SPC throughout all stages of the manufacturing process such as the beginning stages. This report explores the fundamentals of SPC, applicable programs, important aspects of implementation, and specific examples of where SPC was beneficial. Important programs for SPC are general statistical software such as JMP and Minitab, and some programs are made specifically for SPC such as SPACE: statistical process and control environment. Advanced programs like SPACE are beneficial because they can easily assist with creating control charts and setting up rules, alarms and notifications, and reaction mechanisms. After the charts are set up it is important to apply rules to the charts to see when a system is running off target which indicates the need to troubleshoot and investigate. This makes the notification part an integral aspect as well because attention and awareness must be brought to out of control situations. The next important aspect is ensuring there is a reaction mechanism or plan on what to do in the event of an out of control situation and what to do to get the system running back on target. Setting up an SPC system takes time and practice and requires a lot of collaboration with experts who know more about the system or the quality side. Some of the more difficult parts of implementation is getting everyone on board and creating trainings and getting the appropriate personnel trained.

Contributors

Agent

Created

Date Created
  • 2016-12

132240-Thumbnail Image.png

Analyzing the Economic Significance of Implementing a Hydrometallurgical Method of Copper Extraction in Zimbabwe.

Description

Mangura Mine in Zimbabwe has been operating under a traditional copper mining method for the past few decades. This mining method is referred to as the pyrometallurgical process. The process

Mangura Mine in Zimbabwe has been operating under a traditional copper mining method for the past few decades. This mining method is referred to as the pyrometallurgical process. The process involves copper ore extraction, crushing, milling, floatation, concentrating and smelting. With the low copper grades reported at the mine, this multi-stage process is not highly effective to extract this metal. The energy, labor and other expenses incurred in pollution control, have been high. The mine is downsizing every year and it is expected to close in the foreseeable time horizon, even though they still have copper reserves at their property. This project was aimed at providing an effective approach to the future of extracting low grade copper through using a hydrometallurgical extraction process. The hydrometallurgical method is a multi-stage process involving the leaching of copper ore, solvent extraction and electrowinning. The economic viability of implementing a hydrometallurgical process for extracting copper was evaluated. The paper demonstrated the feasibility of the hydrometallurgical process in extracting low grade copper at the mine. A detailed extraction process was developed with the goal of recovering 2.9 million metric tons of copper per year with 99.9 wt.% minimum purity. The return on investment was estimated to be more than 200%. All the findings indicated that implementing a hydrometallurgical process should be the future of Mhangura Mine.

Contributors

Agent

Created

Date Created
  • 2019-05

156838-Thumbnail Image.png

Sensors and Their Applications for Connected Health and Environment

Description

Connected health is an emerging field of science and medicine that enables the collection and integration of personal biometrics and environment, contributing to more precise and accurate assessment of the

Connected health is an emerging field of science and medicine that enables the collection and integration of personal biometrics and environment, contributing to more precise and accurate assessment of the person’s state. It has been proven to help to establish wellbeing as well as prevent, diagnose, and determine the prognosis of chronic diseases. The development of sensing devices for connected health is challenging because devices used in the field of medicine need to meet not only selectivity and sensitivity of detection, but also robustness and performance under hash usage conditions, typically by non-experts in analysis. In this work, the properties and fabrication process of sensors built for sensing devices capable of detection of a biomarker as well as pollutant levels in the environment are discussed. These sensing devices have been developed and perfected with the aim of overcoming the aforementioned challenges and contributing to the evolving connected health field. In the first part of this work, a wireless, solid-state, portable, and continuous ammonia (NH3) gas sensing device is introduced. This device determines the concentration of NH3 contained in a biological sample within five seconds and can wirelessly transmit data to other Bluetooth enabled devices. In this second part of the work, the use of a thermal-based flow meter to assess exhalation rate is evaluated. For this purpose, a mobile device named here mobile indirect calorimeter (MIC) was designed and used to measure resting metabolic rate (RMR) from subjects, which relies on the measure of O2 consumption rate (VO2) and CO2 generation rate (VCO2), and compared to a practical reference method in hospital. In the third part of the work, the sensing selectivity, stability and sensitivity of an aged molecularly imprinted polymer (MIP) selective to the adsorption of hydrocarbons were studied. The optimized material was integrated in tuning fork sensors to detect environmental hydrocarbons, and demonstrated the needed stability for field testing. Finally, the hydrocarbon sensing device was used in conjunction with a MIC to explore potential connections between hydrocarbon exposure level and resting metabolic rate of individuals. Both the hydrocarbon sensing device and the metabolic rate device were under field testing. The correlation between the hydrocarbons and the resting metabolic rate were investigated.

Contributors

Agent

Created

Date Created
  • 2018

158586-Thumbnail Image.png

Point of Care Detection of Iron Metabolism Parameters Through Colorimetric Sensing

Description

Abnormally low or high blood iron levels are common health conditions worldwide and can seriously affect an individual’s overall well-being. A low-cost point-of-care technology that measures blood iron markers with

Abnormally low or high blood iron levels are common health conditions worldwide and can seriously affect an individual’s overall well-being. A low-cost point-of-care technology that measures blood iron markers with a goal of both preventing and treating iron-related disorders represents a significant advancement in medical care delivery systems. Methods: A novel assay equipped with an accurate, storable, and robust dry sensor strip, as well as a smartphone mount and (iPhone) app is used to measure total iron in human serum. The sensor strip has a vertical flow design and is based on an optimized chemical reaction. The reaction strips iron ions from blood-transport proteins, reduces Fe(III) to Fe(II), and chelates Fe(II) with ferene, with the change indicated by a blue color on the strip. The smartphone mount is robust and controls the light source of the color reading App, which is calibrated to obtain output iron concentration results. The real serum samples are then used to assess iron concentrations from the new assay and validated through intra-laboratory and inter-laboratory experiments. The intra-laboratory validation uses an optimized iron detection assay with multi-well plate spectrophotometry. The inter-laboratory validation method is performed in a commercial testing facility (LabCorp). Results: The novel assay with the dry sensor strip and smartphone mount, and App is seen to be sensitive to iron detection with a dynamic range of 50 - 300 µg/dL, sensitivity of 0.00049 µg/dL, coefficient of variation (CV) of 10.5%, and an estimated detection limit of ~15 µg/dL These analytical specifications are useful for predicting iron deficiency and overloads. The optimized reference method has a sensitivity of 0.00093 µg/dL and CV of 2.2%. The correlation of serum iron concentrations (N=20) between the optimized reference method and the novel assay renders a slope of 0.95, and a regression coefficient of 0.98, suggesting that the new assay is accurate. Lastly, a spectrophotometric study of the iron detection reaction kinetics is seen to reveal the reaction order for iron and chelating agent. Conclusion: The new assay is able to provide accurate results in intra- and inter- laboratory validations and has promising features of both mobility and low-cost.

Contributors

Agent

Created

Date Created
  • 2020

155660-Thumbnail Image.png

A Portable Colorimetric Sensing Platform for the Evaluation of Carbon Dioxide in Breath

Description

This work describes the development of a device for measuring CO2 in breath, which has applications in monitoring a variety of health issues, such as Chronic Obstructive Pulmonary Disease (COPD),

This work describes the development of a device for measuring CO2 in breath, which has applications in monitoring a variety of health issues, such as Chronic Obstructive Pulmonary Disease (COPD), asthma, and cardiovascular disease. The device takes advantage of colorimetric sensing technology in order to maintain a low cost and high user-friendliness. The sensor consists of a pH dye, reactive element, and base coated on a highly porous Teflon membrane. The transmittance of the sensor is measured in the device via a simple LED/photodiode system, along with the flow rate, ambient relative humidity, and barometric pressure. The flow is measured by a newly developed flow meter described in this work, the Confined Pitot Tube (CPT) flow meter, which provides a high accuracy with reduced flow-resistance with a standard differential pressure transducer. I demonstrate in this work that the system has a high sensitivity, high specificity, fast time-response, high reproducibility, and good stability. The sensor has a simple calibration method which requires no action by the user, and utilizes a sophisticated, yet lightweight, model in order to predict temperature changes on the sensor during breathing and track changes in water content. It is shown to be effective for measuring CO2 waveform parameters on a breath-by-breath basis, such as End-Tidal CO2, Alveolar Plateau Slope, and Beginning Exhalation Slope.

Contributors

Agent

Created

Date Created
  • 2017