Design and simulation of a high-gain organic operational amplifier for use in quantification of cholesterol in low-cost point-of-care devices

© The Institution of Engineering and Technology. This paper presents circuit design and simulations of a high gain organic Op-Amp, for use in quantification of real cholesterol, in the range of 1-9 mM. A 7-stage inverter chain is added onto the design so as to enhance the amplifier gain. The circuit adapts p-channel transistors only (PMOS) design architecture with saturated loads, simulated on a conventional platform, using appropriate OTFT model and associated parameters. The effect of variation in threshold voltage on circuit operation is also examined. For a supply voltage of ±15 V, the DC output voltage is found to be within an acceptable range of -1 V to -12.5 V, with a highest open loop gain of 83 dB. The closed loop gain is also in agreement with theoretical values, in the range of 1.5 dB to 39 dB, with corresponding bandwidths of 770 Hz to 275 Hz respectively. The latter gain of 39 dB and/or gain-bandwidth product of 10.63 kHz is currently the highest reported in the literature, for this lower supply voltage. The amplifier offers adequate quantification factor, with linear sensitivity of -0.7 V/mM. This paper is the first to adapt organic circuit designs in quantification of cholesterol, with promising outputs, for implementation in low-cost sensor systems

Biosensors for Diagnosis and Monitoring

Biosensor technologies have received a great amount of interest in recent decades, and this has especially been the case in recent years due to the health alert caused by the COVID-19 pandemic. The sensor platform market has grown in recent decades, and the COVID-19 outbreak has led to an increase in the demand for home diagnostics and point-of-care systems. With the evolution of biosensor technology towards portable platforms with a lower cost on-site analysis and a rapid selective and sensitive response, a larger market has opened up for this technology. The evolution of biosensor systems has the opportunity to change classic analysis towards real-time and in situ detection systems, with platforms such as point-of-care and wearables as well as implantable sensors to decentralize chemical and biological analysis, thus reducing industrial and medical costs. This book is dedicated to all the research related to biosensor technologies. Reviews, perspective articles, and research articles in different biosensing areas such as wearable sensors, point-of-care platforms, and pathogen detection for biomedical applications as well as environmental monitoring will introduce the reader to these relevant topics. This book is aimed at scientists and professionals working in the field of biosensors and also provides essential knowledge for students who want to enter the field

Biosensors

A biosensor is defined as a detecting device that combines a transducer with a biologically sensitive and selective component. When a specific target molecule interacts with the biological component, a signal is produced, at transducer level, proportional to the concentration of the substance. Therefore biosensors can measure compounds present in the environment, chemical processes, food and human body at low cost if compared with traditional analytical techniques. This book covers a wide range of aspects and issues related to biosensor technology, bringing together researchers from 11 different countries. The book consists of 16 chapters written by 53 authors. The first four chapters describe several aspects of nanotechnology applied to biosensors. The subsequent section, including three chapters, is devoted to biosensor applications in the fields of drug discovery, diagnostics and bacteria detection. The principles behind optical biosensors and some of their application are discussed in chapters from 8 to 11. The last five chapters treat of microelectronics, interfacing circuits, signal transmission, biotelemetry and algorithms applied to biosensing

Gaseous Electron Multipliers (GEM)-based UV photomultiplier devices

The gain stability of Thick Gaseous Electron Multipliers (ThGEMs) and a novel structure coined gaseous gap electron multiplier (GGEM) was investigated. It was found there was a rising signal over a period of several hours to days which depends on the electric field strength and is only stopped by removing the element from the chamber. Whilst it cannot solely be due to charging of rims as suggested in literature as there is none for GGEMs it could also possibly be due to charging of other dielectric in the chamber. Copper, magnesium and zinc oxide were investigated as possible air-stable ultra-violet (UV) photocathodes. The copper used was from the surface of the printed circuit board (PCB) used in the fabrication of ThGEMs and the copper foil used to make the GGEMs. Magnesium and zinc oxide films were grown via thermal deposition in vacuum, by changing the oxidation methods used when growing the films we are able to get some basic qualitative comparison on how the oxide state effects its properties as a photocathode. Both MgO and ZnO were found to be remarkably stable in air, despite an initial change, they settled to an ambient work function (WF) which was found to change very little for very long periods, such as several months to a year. Mechanically polishing the copper surface with Brasso was found to increase the signal and therefore the quantum yield (QY) by around 5 to 6 times, despite little to no change in measured WF using a Kelvin Probe. It was found using X-ray Photoelectron spectroscopy XPS that polishing the copper surface removed the CuO/Cu(OH)2 leaving behind more metallic copper which must have a higher QY. For both MgO and ZnO films it was found that if the samples were oxidised in vacuum they appeared to have lower work function than if oxidised in ambient conditions. From XPS measurements the increase in work function was attributed to a larger MgCO3 and hydrozincite components respectively. With the decrease in WF with ambient exposure being attributed to a larger MgO component. Both MgO and ZnO were found to have a range of possible signals, in part due to the rising gain behaviour, however there was a general trend of lower WF resulted in higher signal. Some possible applications for ThGEM-based Gaseous Photomultiplier (GPM) devices have been investigated, in particular real-time water monitoring which we showed is possible by investigating the quantities of 3 different chemicals: potassium hydrogen phthalate, clothiandin and tryptophan

Hybrid microfluidic CMOS capacitive sensors for lab-on-chip applications

Methods and applications of CMOS-based Locs -- Hybrid microfluidic/cmos platform -- Cmos based capacitive sensors for locs -- Direct-write microfluidic packaging procedure -- Core-cbcm capacitive sensor array for locs

Towards Stable Electrochemical Sensing for Wearable Wound Monitoring

Wearable biosensing has the tremendous advantage of providing point-of-care diagnosis and convenient therapy. In this research, methods to stabilize the electrochemical sensing response from detection of target biomolecules, Uric Acid (UA) and Xanthine, closely linked to wound healing, have been investigated. Different kinds of materials have been explored to address such detection from a wearable, healing platform. Electrochemical sensing modalities have been implemented in the detection of purine metabolites, UA and Xanthine, in the physiologically relevant ranges of the respective biomarkers. A correlation can be drawn between the concentrations of these bio-analytes and wound severity, thus offering probable quantitative insights on wound healing progression. These insights attempt to contribute in reducing some impacts of the financial structure on the healthcare economy associated with wound-care. An enzymatic electrochemical sensing system was designed to provide quick response at a cost-effective, miniaturized scale. Robust enzyme immobilization protocols have assisted in preserving enzyme activity to offer stable response under relevant variations of temperature and pH, from normal. Increased hydrophilicity of the sensor surface using corona plasma, has assisted in improving conductivity, thus allowing for increased electroactive functionalization and loading across the substrate’s surface. Superior sensor response was attained from higher loading of nanomaterials (MWCNT/AuNP) and enzymes (UOx/XO) employed in detection. Potentiometric analyses of the nanomaterial modified enzymatic biosensors were conducted using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) modalities. Under relevant physiological conditions, the biosensor was noted to offer a variation in response between 10 % and 30 % within a week. Stable, reproducible results were obtained from repeated use of the biosensor over multiple days, also offering promise for continuous monitoring. Shelf life of the biosensor was noted to be more than two days with response retained by about 80 % thereafter. Secondary analyses have been performed utilizing the enzymatic biosensor to explore the feasibility of target biomarker detection from clinical extracts of different biofluids for wound monitoring. Biosensor response evaluation from the extracts of human wound exudate, and those obtained from perilesional and healthy skin, provided an average recovery between 107 % and 110 % with a deviation within (+/-) 6 %. Gradual decrease in response (10-20 %) was noted in detection from extracts further away from injury site. Increased accumulation of biofluids on the sensor surface was studied to explore sensor response stability as a function of sample volume. With a broad linear range of detection (0.1 nM – 7.3 mM) and detection limits lower than the physiological concentrations, this study has assessed the viability of stable wound monitoring under physiologically relevant conditions on a wearable platform

Data Acquisition Applications

Data acquisition systems have numerous applications. This book has a total of 13 chapters and is divided into three sections: Industrial applications, Medical applications and Scientific experiments. The chapters are written by experts from around the world, while the targeted audience for this book includes professionals who are designers or researchers in the field of data acquisition systems. Faculty members and graduate students could also benefit from the book

Advances in Bioengineering

The technological approach and the high level of innovation make bioengineering extremely dynamic and this forces researchers to continuous updating. It involves the publication of the results of the latest scientific research. This book covers a wide range of aspects and issues related to advances in bioengineering research with a particular focus on innovative technologies and applications. The book consists of 13 scientific contributions divided in four sections: Materials Science; Biosensors. Electronics and Telemetry; Light Therapy; Computing and Analysis Techniques

Polarized Light Applications towards Biomedical Diagnosis and Monitoring

Utilization of polarized light for improved specificity and sensitivity in disease diagnosis is occurring more often in fields of sensing, measurement, and medical diagnostics. This dissertation focuses on two distinct areas where polarized light is applied in biomedical sensing/monitoring: The first portion of worked reported in this dissertation focuses on addressing several major obstacles that exist prohibiting the use of polarized light as a means of developing an optical based non-invasive polarimetric glucose sensor to improve the quality of life and disease monitoring for millions of people currently afflicted by diabetes mellitus. In this work there are two key areas, which were focused on that require further technical advances for the technology to be realized as a viable solution. First, in vivo studies performed on New Zealand White (NZW) rabbits using a dual-wavelength polarimeter were conducted to allow for performance validation and modeling for predictive glucose measurements accounting for the time delay associated with blood aqueous humor glucose concentrations in addition to overcoming motion induced birefringence utilizing multiple linear regression analysis. Further, feasibility of non-matched index of refraction eye coupling between the system and corneal surface was evaluated using modeling and verified with in vitro testing validation. The system was initially modeled followed by construction of the non-matched coupling configuration for testing in vitro. The second half of the dissertation focuses on the use of polarized light microscopy designed, built, and tested as a low-cost high quality cellphone based polarimetric imaging system to aid medical health professionals in improved diagnosis of disease in the clinic and in low-resource settings. Malaria remains a major global health burden and new methods for, low-cost, high-sensitivity diagnosis of malaria are needed particularly in remote low-resource areas throughout the world. Here, a cost effective optical cell-phone based transmission polarized light microscope system is presented utilized for imaging the malaria pigment known as hemozoin. Validation testing of the optical resolution required to provide diagnosis similar to commercial polarized imaging systems will be conducted and the optimal design will be utilized in addition to image processing to improve the diagnostic capability