bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication of a Room Temperature Electrochemical Gas Sensor Using Paper Substrate
Authors: Sekhar Praveen K. , Kysar Jesse 
Published: February 2020

Recent increases in threats to public health, safety, and security have generated a need for more reliable and rapid detection of volatile and toxic gases. To achieve a reliable and versatile gas sensing system capable of being fabricated at the micro-scale a sensor with high selectivity, rapid response time, and low power requirements that is capable of being fabricated easily with low cost at the micro-scale is needed. A promising new approach to detecting gases is by electrochemical sensing using room temperature ionic liquids (RTILs) as the sensing electrolyte. Electrochemical methods of detecting gases provide superior selectivity with low power consumption and have a wide range of gases that can be detected. RTILs are stable conductive ionic compounds which are liquid at room temperature but that also have extremely low vapor pressure, high thermal stability, and wide potential windows. These traits combined with the capability of room temperature operation gives RTIL sensors a distinct edge over traditional heated gas sensing technology. Combining this fundamental sensor structure with electrochemical measurement techniques such as electrochemical impedance spectroscopy (EIS) and amperometry allows for simple and reliable detection of a variety of gases. The hurdle of delayed response of RTIL sensors due to diffusion of the target gas is overcome by ink jet printing the circuitry, electrodes and the RTIL on high temperature resistant, flame resistant paper. The added benefits of using the fabrication method of ink jet printing are reduced cost and in situ fabrication. Printing on paper reduces cost and adds flexibility and durability to open up this versatile sensor to applications such as wearable sensors as an early warning system for areas where hazardous gases can cause serious injury or even death and further incorporation of sensors in transit security, for instance by embedding them in luggage tags.
This research presents a room temperature ionic liquid (RTIL) gas sensors printed with on flexible and low cost heat resistant paper substrate. The electrodes are ink jet printed using both indium tin oxide and gold ink separately to achieve the optimum design for reliability, speed, precision, selectivity, size and cost. The fabrication process for a 1mm x 1mm RTIL gas sensor is presented with the measured responses to methane and ammonia. This flexible, inexpensive, and wearable sensor structure allows for widespread deployment of gas sensing technology in security sensitive or crowded public, government, and transit areas.
Faster Diagnosis of Alpha-1-Antitrypsin Deficiency through Electrochemical and Quartz Crystal Microbalance Testing
Authors: Materi Bryan Evans , Adams Bobby Gene , Sanders Jonathan , Rice Jeffrey , Rice Cynthia A. 
Published: February 2020

Alpha-1-Antitrypsin (A1AT) Deficiency (A1AD) is a potentially debilitating inherited condition that can lead to reduced levels of A1AT in the lungs and increased levels in the liver. In the lungs, the condition is routinely associated with an imbalance in levels of Human Neutrophil Elastase (HNE) and its native inhibitor A1AT (predisposing those affected to early-onset emphysema). In the liver, certain genetic mutations lead to an accumulation of A1AT. No cure exists, and current approaches for diagnosis are insufficient as illustrated by the fact that A1AD is underdiagnosed and diagnosis is often delayed.1New methods for diagnosis are needed, and one possible route is the use of electrochemical techniques combined with quartz crystal microbalance (QCM) approaches.
Often, QCM and electrochemistry are combined using a gold working electrode that has been functionalized with a particular molecule. In our case, Porcine Pancreatic elastase (PPE), a surrogate of HNE, has been used as an enzymatic marker. When a potentiostat was combined in parallel to the apparatus, measurements of both the frequency and the current responses were simultaneously performed. PPE was immobilized to the surface of the gold electrode through the use of a crosslinker. The immobilized PPE was then incubated with various concentrations of N-Succinyl-Ala-Ala-Ala-p-Nitroanalide (SApNA), a chromogenic substrate for elastase, allowed to react, and the absorbance measured to determine the activity of the enzyme. This same test was also completed with the A1AT inhibitor in the solution with the SApNA and the absorbance measured again. From these results, the frequency was measured and converted to mass to determine the extent of inhibition. This data was then examined via kinetics-based models to estimate the kinetic parameters of inhibition.
Electrochemical measurements have been performed concurrently with the frequency measurements. Using phosphate buffered saline (PBS) in the presence of ferrocyanide/ferricyanide as the redox species, cyclic voltammetry was performed to determine the extent that the electrode surface is covered. As the SApNA and A1AT was added to the solution, the change in the ferrocyanide/ferricyanide peaks were observed.
It is the ultimate goal of this work to develop a test that can be used to determine the inhibition kinetics of HNE via A1AT, and thus shed light on new approaches to diagnose A1AD. Such an approach could also serve as a platform that could be useful in the early detection and diagnosis of many different diseases that could allow for preemptive treatment and could potentially improve life expectancy outcomes for those afflicted.

American Thoracic Society/European Respiratory Society Statement: Standards for the Diagnosis and Management of Individuals with Alpha-1-Antitrypsin Deficiency. (2003). Am. J. Respir. Crit. Care Med. 168(7): 818-900.
Breast-Cancer-Stem-Cell Sensor Using Igzo Nomfet Implemented with Au Nano-Particles
Authors: Lee Jong-Sun , Song Seung-Hyun , Kim Chul Geun , Park Jea-Gun 
Published: February 2020

Recently, many researchers have studied circulating-cancer-stem-cell (CCSC) to pre-recognize the presence of a cancer. Since, it has been that cancer cells include negative or positive charges, several electronic sensors have been attractively proposed. In our study, we designed an In-Ga-Zn-oxide (IGZO) based FET implemented with Au nano-particles on IGZO channel, as shown in Fig. 1(a). The average size and density of the Au nano-particles on the channel were 12.05 nm and 2.66×1011 cm-2, respectively. In particular, this FET has a unique time-dependent current characteristic such as depressing at a positive gate bias or facilitating at a negative bias, which determines whether or not the cancers present a fixed charge or mobile charges. In our experiment, breast-cancer-stem-cell (BCSC) connected with the cancer-anti-body (CD44) was dropped on the IGZO FET with Au nano-particles where a linker (8-Mercaptooctanoic acid) was attached on Au nano-particles, as shown in Fig. 1(b). The linkers were well uniformly absorbed and attached on Au nano-particles, confirmed by FT-IR, as shown in Fig. 2. First of all, we investigated the dependency of threshold voltage on the presence of Au nano-particles, linkers, and breast-cancer-stem-cells with anti-bodies shown in Fig.3. The threshold voltage of the IGZO FET without Au nano-particles was +2.4 V. The implementation of Au-nano-particles on the IGZO channel increased from +2.4 to +12.0 V because of the presence of positive fixed charges at the interface between the IGZO channel and Au nano-particles. The attachment of the linker on Au nano-particles decreased the threshold voltage from +12.0 V to +6.9 V since the functional group of the linker was carboxyl. Two kinds of breast-cancer-stem-cells were dropped on the linker connected with Au-nano-particles; i.e., the cells without or with anti-body. The cells without anti-body did not shift threshold while the cells with anti-body reduced -4.3 V where the concentration of BCSC was 8000ea/10ul. The threshold-voltage shift amount was well correlated with the concentration of BCSC, as shown in Fig. 4. The threshold-voltage shift amount increased linearly with the concentration of BCSC, having the slope of the threshold-voltage shift amount of 0.44V/(kea/ul). In addition, we confirmed that BCSC showed a negative fixed charge rather than mobile charge by testing time dependent drain-current characteristic. In our presentation, we will review the detailed mechanism by which BCSCs shift threshold voltage and show a negative fixed charge characteristic.

Reference

[1] F. Alibart et al. Adv. Funct. Mater. 20 330. (2010)
[2] K.-C. Kwon et al. Appl. Phys. Exp. 6, 067001 (2013).
[3] XiuHua Zhang
et al. Sensors, 3, 61-68 (2003)

Acknowledgment

This research was supported by the Converging Research Center Program funded by the Ministry of Science, ICT & Future Planning (Project No. 2015054348) and supported by Brain Korea 21 PLUS Program in 2014

Figure 1
Effects of Porous Structure for Gas Sensor on Sensitivity Using Tin Oxide with Low Density
Authors: Han Min-Ah , Jeong Ji Hea , Noh Hee Jun , Kim Hyun-Jong , Son Seong Ho , Park Jin-Seong , Lee Ho-Nyun 
Published: February 2020

Recently, gas sensor has been studied because of increasing accidents caused by harmful and explosive gas, which is hard to detect olfactory system. Tin oxide is one of the most promising candidates for gas sensing materials owing to its many advantages, such as various gas detecting capability, good stability and high sensitivity.
In gas sensor, the kinds of sensing materials as well as detecting layer structures are important. The sensing materials with high surface areas show high sensing performance, so nanowire structure with mechanical contact between nanowires has been widely used. However, electric signal of nanowire along mechanical contacts is not stable and the external vibration and fast gas flow generates the inaccurate signal.
In this research, the low density tin oxide film with stable interconnection between nanoparticles was prepared using the physical vapor deposition by controlling the processing pressure, temperature and power. Macrostructure and interconnected structure between tin oxide nanoparticles were observed using scanning electron microscope (SEM) and transmission electron microscope (TEM) and crystal structure was analyzed by X-ray diffraction (XRD). Platinum and titanium electrodes were fabricated by lift-off process on the silicon substrate with the silicon nitride film of 300 nm, and then tin oxide with low density was deposited on it using shadow mask. The characteristics of the gas sensor were examined using carbon mono-oxide (CO) and ethanol (C2H5OH) changing concentration of gas, operating temperature and post heat-treatment temperature. In conclusion, porous nanostructure of tin oxide was composed of a lot of interconnected nanoparticles of about 10 nm and showed stable resistance in dry air. And post heat-treatment enhanced the stability in spite of inreasing the particle size. It could be suggested that the oxide films with lower density showed the superior sensitivity and the shorter response time than the oxide films with higher density.

Figure 1
Graphene Quantum Dots As Optical Sensor for Glucose Detection
Authors: Abdel-Fattah Tarek M , Ebrahim Shaker , Soliman Moataz , Shehab Mona 
Published: February 2020

Graphene Quantum Dots (GQDs) show promise for many technological applications because GQDs have low toxicity and are chemically inert, biocompatible, and resistant to photobleaching [1].
We report a simple route to prepare graphene quantum dots (GQDs) using glucose carbonization. GQDs functionalized with phenylboronic acid receptors were employed as a sensing material for a nonenzymatic glucose sensor. GQDs display high surface area and the carboxylic moieties at their edges provide them with water dispersibility and proper functional groups to be complexed with several compounds [2]. Therefore, GQDs considered as a good sensing probe. The prepared GQDs were characterized using different techniques such as UV-visible and photoluminance spectroscopies, X-ray diffraction, transmission electron microscopy (TEM) and Raman spectroscopy. TEM micrographs confirmed the preparation of 8-10 nm GQDs. The emission peak of the GQDs appears at 450 nm. The developed sensor has linear response to glucose over a concentration range of 5 -50 mM.
References:
1) Shen, J.; Zhu, Y.; Yang, X.; Li, C. Graphene Quantum Dots: Emergent Nanolights for Bioimaging, Sensors, Catalysis and Photovoltaic Devices. Chem. Commun. 2012, 48, 3686.
2) Liu, J.-J.; Zhang, X.-L.; Cong, Z.-X.; Chen, Z.-T.; Yang, H.-H.; Chen, G.-N. Glutathione Functionalized Graphene Quantum Dots as Selective Fluorescent Probes for Phosphate-Containing Metabolites. Nanoscale 2013, 5, 1810−1815
The Study of Self-Assembled Au Nanoparticles As an Efficient SERS Substrate for Environmental Sensing Applications
Authors: Flowers Jasmin , Rutherford Gugu , Jenrette Erin , Farrell Monique , Skuza Jonathan , Fletcher Sha'La , Carvajal Christian G , Pradhan Aswini K 
Published: February 2020

The formation of self-assembled monolayers (SAM) of noble metals for optical sensing applications faces serious challenges when trying to achieve simplicity, cost efficacy, specificity, and versatility. Utilizing stable, SAM-forming alkanethiols, such as glutathione (GSH), enable for simple assembly and specific detection of proteins, trace metals, oxidants, etc., thus providing a sensing platform that not only can detect low levels of reactive oxygen species (ROS) for early determination of neurodegenerative diseases, but can also assess trace metals in freshwaters and marine waters, for example. Providing a universal device for detecting varieties of target materials would adapt, simplify, and reduce costs that come from current detection methods. Our research on improving these detection methods is demonstrated using the frequency-controlled self-assembly of a GSH-functionalized gold nanoparticle (Au NP) film as a platform for highly specific and sensitive sensing. We have previously demonstrated the use of an eco-friendly and highly sensitive surface enhanced Raman spectroscopy (SERS) substrate for biomedical diagnostic applications using an ultraviolet photochemical reaction of gold (III) chloride trihydrate (HAuCl4) to create a densely packed Au NP film that exhibits localized surface plasmon resonances [1]. By the firm anchoring of a thiol group to the Au NP surface, GSH assembles the Au NPs for SERS into a densely packed, dendritic structure. At a pH of ~1 in solution, GSH forms a y-shape [2], allowing its carboxyl and amino groups to create a hydrophilic interface and, therefore, be fully available for bonding to various functional molecules. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible spectroscopy (UV-vis) were used to confirm the presence of GSH and enhancement capabilities of the SERS substrate. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed the Au NP film to be 90nm thick, with an average Au NP size of 125nm in diameter [1], and visually confirmed the dendritic assembly of the GSH-functionalized Au NPs. For application purposes, this study will evaluate the trace metal Pb2+ in water. The contamination of lead, and heavy metals in general, have a damaging impact on the health of both humans and our planet. The chelation of the GSH ligands with Pb2+ enables highly specific detection of Pb2+ in water. This method provides a simple, versatile SERS substrate with a dendritic assembly that creates intriguing optical properties and broadens the capability for potential applications.
[1] G. Rutherford et al., ECS J. Solid State Sci. Tech. 4, S3071 (2015).
[2] M. Bieri and T. Burgi, Langmuir
2005, 21, 1354-1362.

Figure 1
Mobile Water Kit 2.0: A Field Deployable Solution for E. coli Detection in Potable Water
Authors: Gunda Naga Siva , Chavali Ravi , Mitra Sushanta 
Published: February 2020

Escherichia coli (E.coli) is an indicator organism, the presence of which in potable water suggests that the water source has been compromised. Consumption of such water would cause huge health problem and even human mortality. However, one of the key challenges for water quality monitoring is to detect such indicator organism right at the source or at the point of consumption. Current technologies rely on collecting water samples and sending samples to microbiological laboratories, which through membrane filtration and plate count, provide conclusive results, typically within 24 – 48 hrs. Such lengthy wait period is very much precarious to the communities, particularly in rural Canada, counties in US, and limited resource regions of developing economies (i.e., India, China, Brazil), where even access to a reliable water quality monitoring laboratory is questionable.
In response to this global issue, we have developed a low-cost and extremely efficient test method known as the Mobile Water Kit (MWK) [Gunda et al., Analytical Methods, 6, (16), 6236-6246, 2014], which has greatly simplified the process of E.coli detection in the field, which wasn’t feasible until recently. The MWK can accurately detect extremely low concentrations of E.coli (2 CFU/100 mL) under an hour and is faster than the current conventional laboratory methods, which requires 24 to 48 hours to produce proper results. However, MWK may require a trained technician to perform the test as there are number of steps involved for water testing starting from collecting the water sample to broadcasting of test results. Moreover, MWK contains the chemical reagents in liquid form to be stored and handled in a careful and manageable way. In the present work, we resolved these two impediments by the following modifications to MWK: (a) reduced the number of steps required to perform water testing; (b) converted the liquid based system to a hydrogel impregnated chemical reagent based system (i.e., porous soft material) for ease of handling and deployment. This revised version of MWK (i.e., MWK 2.0) simplifies the testing method and make it amenable for regular field use without the help of a trained technician. In addition, the MWK 2.0 replaces syringes, filters, centrifuge tubes, pipette tips, etc., which were essential components for the original version of MWK. Moreover, MWK 2.0 allows sample concentration and detection in one single step. With MWK 2.0, we were able to detect E.coli concentrations of 4x106 CFU/mL to 4x105 CFU/mL within 5 min and 4x104 CFU/mL to 40 CFU/mL within 60 min.
(Invited) Where Is Dielectrophoresis (DEP) Going?
Authors: Pethig Ronald 
Published: February 2020

Fifty years have passed since the first demonstration that DEP can be applied to the biomedical sciences. Pohl and Hawk [1] gave the first report of a purely physical technique being used to simultaneously distinguish and separate live and dead yeast cells. Over the past 50 years the theoretical aspects of DEP have attained a high level of refinement, whilst applications that include the manipulation of DNA, proteins, viruses, bacteria, blood cells, cancer cells and stem cells have been demonstrated. Stainless steel electrodes [1] used to generate the required high field gradients have been replaced by devices taking advantage of microfabrication and microfluidics, ranging from: microelectrode arrays [2]; insulator-based DEP [3, 4]; streaming DEP [5]; liquid electrodes [6]; carbon electrodes [7].
The key advances and relative advantages or otherwise of these various DEP techniques will be reviewed, with the aim to identify niche biomedical applications.

1. Pohl, H. A., Hawk, I. (1966) Separation of living and dead cells by dielectrophoresis, Science 152, 647-649.
2. Price, J. A. R., Burt, J. P. H., Pethig, R. (1988) Applications of a new optical technique for measuring the dielectrophoretic behaviour of micro-organisms, Biochim. Biophys. Acta 964, 221-230.
3. Masuda, S., Washizu, M., Nanba, T. (1989) Novel method of cell-fusion in field constriction area in fluid integrated circuit, IEEE Trans. Ind. Appl., 25, 732-737.
4. Chou, C-F., Tegenfeldt, J. O., Bakajin, O., Chan, S. S., Cox, E. C., Darnton, N., Duke, T., Austin, R. H. (2002) Electrodeless dielectrophoresis of single- and double-stranded DNA, Biophys. J., 83, 2170-2179.
5. Cummings, E. B., Singh, A. K. (2003) Dielectro-phoresis in microchips containing arrays of insulating posts: theoretical and experimental results, Anal. Chem., 75, 4724-4731.
6. Demierre, N., Braschler, T., Linderholm, P., Seger, U., van Lintel, H., Renaud, P. (2007) Characterization and optimization of liquid electrodes for lateral dielectro-phoresis, Lab Chip 7, 355-365.
7. Martinez-Duarte, R., Camacho-Alanis, F., Renaud, P., Ros, A. (2013) Dielectrophoresis of lambda-DNA using 3D carbon electrodes, Electrophoresis 34, 1113-1122.
Process Integration of Electroformed MEMS Variable Capacitors for Magnetostriction Measurements
Authors: Finnegan Patrick Sean , Langlois Eric D , Arrington Christian L. , Hollowell Andrew E , Pillars Jamin Ryan , Monson Todd , St. John Christopher R. 
Published: February 2020

Electrochemically deposited CoFe and CoFeB films are being studied for use as wireless remote sensors. Coded signals can be achieved through passive devices and interrogated to produce electronic signatures that are nearly impossible to replicate or counterfeit. A MEMS variable capacitor is being fabricated from a novel electroformed process with CoFe and CoFeB magnetostrictive films. This approach to MEMS fabrication is being used to incorporate electroplated ferric alloys into a variable capacitor, to study Joule magnetostriction. Such alloys are capable of a large change in material shape when subjected to a magnetic field. Integrating these films with a variable capacitor MEMS device allows for a unique approach to provide accurate microstrain measurements in low magnetic fields up to saturation, to provide feedback for the optimization without the use of expensive commercial setups. This process is unique to MEMS device fabrication and is differentiated by the use of a planar layered approach. Maintaining planarity by manipulating oxides to form electroplating molds, as well as provide a sacrificial material, results in an electrochemically deposited cantilever structure with an integrated magnetostrictive sensing element. This presentation will discuss the fabrication process of these devices. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000