bluuebunny/crossref_metadata_2025 huggingface dataset:
Visible Light-Driven Photoelectrochemical Platform Based Biosensor
Authors: Ganganboina Akhilesh BABU
Published: November 2022

The characterization of the photoinduced carriers' production, separation, and interfacial reaction processes is critical in developing effective photoelectrochemical (PEC) detection. The design and fabrication of a visible-light-driven PEC device based on CdSe-Co3O4@TiO2 nanoflower are presented in this report. In addition, an application for the ultrasensitive detection of viruses, including hepatitis E virus (HEV), HEV-like particles (HEV-LPs), and SARS-CoV-2 spike protein in complex lysate solution. The photocurrent response output of a CdSe-Co3O4@TiO2 based PEC device is improved compared to the individual components, TiO2 and CdSe-Co3O4. This can be ascribed to forming a heterojunction structure obtained by the hybridization of TiO2 and CdSe-Co3O4. CdSe QDs sensitization effect and strong visible light absorption can extend interfacial carrier lifetime and enhance energy conversion efficiency coupling with a robust oxygen-evolving catalyst (Co3O4) at the hole trapping site (CdSe) to improve overall system stability. The developed PEC-based biosensing device has been effectively used for quantitative virus detection through effective hybridization among antibody and viral specimens. The effective capture of the virus resulted in a linear relationship of change in photocurrent output versus the HEV concentration ranging from 10 fg mL–1 to 100 ng mL–1 with a detection limit of 3.5 fg mL–1. This CdSe-Co3O4@TiO2-based PEC device shows a significant ability to develop an improved device with affordable and portable biosensing capabilities.
Electrochemiluminescence: Digging into the Past and Illuminating the Future
Authors: Brown Kelly , Dennany Lynn
Published: November 2022

Despite its discovery in the 1960’s electrochemiluminescence (ECL) has only in recent years seen an increased popularity within the wider analytical community. This can be largely correlated to the improvements in technology within the last decade which have facilitated the reduction in instrument size and complexity, so much so that today the technique can be performed through modification of a smartphone device. As such, ECL can now be considered a powerful addition to the analytical toolbox, with ever expanding reach of the technique into new areas of analytical science.

This research aims to further expand the understanding of potential utilisation of the technique by displaying its fundamental success for applications into previously underrepresented or unique fields. Through the combination of screen printed electrodes with different metal luminophores and modification strategies a number of sensing systems, building upon the traditional ruthenium based devices, has been achieved. Preliminary research has displayed, through the unique characteristics offered by ECL, successful application to the archeological, horticultural, and veterinary fields. Each sample type offered unique challenges, with the final outcome offering an in-field compatible and potentially non-destructive analysis method. Further attributes include minimal sample preparation procedures and volumes alongside simplistic operation and interpretation further enhancing its usability making it an ideal candidate for non-experts or indeed electrochemists.

Here we display exciting opportunities for the expansion of not only of ECL but electro-analytical devices toward a range of unusual and unique environments. Such areas have either minimal or no past experience in the utilisation of ECL for direct target analysis, and as such we hope to successfully demonstrate its capabilities. Through promotion of the versatility of the technique into new arenas we hope to drive forward the expansion of ECL both within the analytical community but also beyond, by sparking interesting in this fundamentally promising technique from outwith the electrochemical and ECL communities.
Influence of Ascorbic Acid Concentration on Photoelectrochemical Response of TiO2 and SnS2
Authors: Radic Gabrijela , Juric Kacunic Danijela , Perovic Klara , Kusic Hrvoje , Kraljic Rokovic Marijana
Published: November 2022

TiO2 is already a well-studied photocatalytic material because of its excellent properties such as chemical stability, low price and non-toxicity. However, the fact that its band gap (3,2 eV) allows it to absorb only the UV light limits its use. On the other hand, the SnS2 (band gap ~2,2 eV) absorption range is well within the visible light spectrum, which is more suitable for solar harvesting. Both of these materials yield rapidly recombining electron-hole pairs upon photoexcitation. This recombination can be prevented by the addition of hole scavengers, which increase the survival probability of the electrons. Over the years there have been various efforts to improve such reaction efficiency using different hole scavengers. This work was focused on the influence of ascorbic acid (AA) on the photoelectrochemical response of TiO2 and SnS2 [1].

The obtained results indicated that by using an AA solution photocurrents response significantly increases confirming its good hole scavenging properties. Additionally, it was shown that by increasing AA concentration from 10 mM to 100 mM TiO2 photoactivity was not improved while SnS2 photoactivity significantly increased. The photoactivity was determined by using linear sweep voltammetry, electrochemical impedance spectroscopy and open circuit potential monitoring. The interaction of AA and metal oxide was studied by UV/Vis spectroscopy.

[1] A. Indra, R. Beltrán-Suito, M. Müller, R.P. Sivasankaran, M. Schwarze, A. Acharjya, B. Pradhan, J. Hofkens, Promoting Photocatalytic Hydrogen Evolution Activity of Graphitic Carbon Nitride with Hole-Transfer Agents, ChemSusChem, 14, (2020), 306-312, doi: https://doi.org/10.1002/cssc.202002500

This research
has
been
supported
by
European
Structural
and
Investment
Funds
,
Water
Purification
and
Energy
Conversion
using
Novel
Composite
Materials
and
Solar
Irradiation
, KK.01.1.1.04.0001 and Croatian
Science
Foundation
under
the
project NaSCEnT (IP-2018-01-1982).
Electrochemical Methodologies for the Detection of Traditional and Emerging Illicit Drugs
Authors: Blake Rowan Sirkka , Brown Kelly , Dennany Lynn
Published: November 2022

Drug abuse and drug addiction is a multifaceted problem which has for a long time had far-reaching societal and physical consequences. In recent years, these negative effects have been further exacerbated by an increase in the production, trafficking and consumption of illicit drugs. Furthermore, the introduction of potent synthetic analogues and compounds known as New Psychoactive Substances (NPS) to the illicit drug market and their rapid proliferation has lead to an unprecedented threat to public health and safety. As such, the necessity has grown for the development of robust screening methodologies for these compounds within forensic and clinical research. Electroanalytical chemistry has quickly become a popular and powerful tool to address such demands. Electrochemical sensors evade many of the pitfalls associated with conventional detection methods, allowing for exceptionally good analytical performance at minimal cost.

Within this contribution we present the use of electrochemiluminescence (ECL) as a novel screening methodology for the detection of Synthetic Cannabinoids (SCs), which are the most prevalent group of NPS currently being monitored by the European Monitoring Centre for Drugs and Drug Addiction. AB-CHMICA, NE-CHMIMO, BB-22 and 5F-ADB-PINACA were all successfully detected at relevant concentrations using the developed screen-printed electrode ruthenium-based sensor. While in its infancy, these results show the potential of ECL as a screening methodology for SCs and leave much to be explored including its applicability to street and biological samples.

Moreover, we aim to highlight the diversity of electrochemical techniques toward illicit drug detection via investigation into the use of wearable electrochemical sensors for the detection of traditional cannabinoids and benzodiazepines.
Development and Improvement of an Electrochemical Cell for X-Ray Fluorescence and Absorption Spectroscopy
Authors: Lopez-Astacio Hiram J , Cunci Lisandro , Pollock Christopher
Published: November 2022

The use of X-ray spectroscopy is an essential technique for the study of any material. Our research investigated the electrochemical cell design and improvement for X-ray absorption and fluorescence spectroscopy. Our objective was to improve the design capability of the current electrochemical cell design to perform absorption and fluorescence spectroscopy at once. By changing the geometry of the receiving window on the electrochemical cell, we could accomplish both fluorescence and absorption spectroscopy functions for CHEXS experiments. Our approach was a simple, inexpensive prototype cycle that anyone could use. Using a hobbyist Computer Numerical Control (CNC) and free 3D CAD software, anyone can develop a reliable electrochemical cell using our design. The electrochemical cell was fabricated using a small computer numerical control system, which allowed a fast turnaround for our project. Our work contributed to designing an open-source electrochemical cell that CHESS or any user could use, modify and share for future projects. Scientifically, we aimed to implement the ability to do both fluorescence and absorption spectroscopy, incorporate the ability to purge the cell with a gas, decrease ionic resistance in the cell to have all the electrodes within the same cell, and avoid leaks.

The development of a new electrochemical cell design was made to improve the reliability and performance of the cell for CHESS experiments. By re-arranging the positions of the working electrode (WE), counter electrode (CE), and reference electrode (RE), we accomplished low ionic resistance within the cell. In addition, creating a 45-degree angle slope on both sides of the X-ray receiving window will allow the design of the electrochemical cell to perform fluorescence and absorption spectroscopy simultaneously. Furthermore, an add-on to the top of the electrochemical cell was designed to perform gas purging of the cell successfully. Lastly, the change from an o-ring to a gasket addressed the leakage problem thoroughly.
(Digital Presentation) In-Situ Investigation of Pyridine in CO2 Electrochemistry
Authors: Noguchi Hidenori , Chase Zizwe
Published: November 2022

CO2 emissions are a major factor that contributes to global warming and climate change. Therefore converting CO2 to useful chemicals that can be used for energy or industrial needs is essential. Electrochemical reactions (ECRs) with Pt electrodes have been extensively studied for CO2 reduction and have shown to heavily favor the hydrogen reduction reaction but there has been a dispute as to whether the addition of pyridine enhanced the production of organic compounds. In-situ use of Sum Frequency Generation spectroscopy during the ECR of CO2, shows that intermediates and products for organic product formation do not appear at the reaction interface and that pyridine most likely lays flat on the catalytic surface possibly blocking CO2 adsorption sites.
Analysis of As(III) By Anodic Stripping Voltammetry Using Disc and Screen Printed Electrodes
Authors: Vyas Ritesh Navneetrai , Brankle Dane
Published: November 2022

Determination of arsenic is possible by various methods such as spectrophotometry, atomic absorption (as arsine), atomic emission, and neutron activation analysis are common. High levels of interference and the high costs of these methods are major drawbacks. Anodic stripping voltammetry (ASV) has proved to be a sensitive, precise, and cost-effective electroanalytical technique for determining trace metals. It is routinely used for detecting Pb (II) and Cd (II). The general procedure of this technique involves depositing metal(s) at a reductive potential into Hg electrodes for a certain time and stripping them back into the solution by scanning the potential in the oxidative direction. In this work, the analysis of As (III) by ASV has been investigated using solid and Screen Printed Gold electrodes. Improved detection limits up to 10 ppb could be achieved with relative ease. A highly optimized procedure has been presented for the BASi Epsilon users that automatically provides electrochemical pretreatment in automated fashion along with the built-in differential pulse stripping voltammetry in the next step.
Trace Level Quantification of Lead in Michigan Lake Water Using Differential Pulse Stripping Voltammetry: A Comparative Study on the Usage of Mercury Based Electrodes Vs Solid State Gold Electrodes
Authors: Vyas Ritesh Navneetrai , Brankle Dane
Published: November 2022

The concentration of lead in fresh-water samples from the southern shoreline of Lake Michigan was analysed and compared using two different cell-stands: Controlled Growth Mercury Electrode (CGME) and voltammetry cell stand with disk type gold electrode. Clearly visible Lead (II) peaks at -395 mV and 130 mV were obtained with CGME and Au electrodes respectively using anodic stripping voltammetry (ASV) technique. Sensitivity, reproducibility, and ease of usage were differentiated for each method. While the measured lead concentration was 2.4 ppb using CGME set-up a closely similar concentration of 2.7 ppb was obtained with the gold disk electrode set-up and thereby confirms the availability of Hg-free detection of lead. The sensitivity obtained from the standard addition curve using the gold electrode was also over twice that of the CGME. The difference in background currents was attributed to the different electrode materials, bulk diffusion in electrolyte of lead ions, electrode-electrolyte interface and the relative surface areas of the electrode surface. Even after repeated polishing of gold electrodes in each run, its inherent sensitivity makes it an ideal candidate for lead determinations with no further requirement of handling the hazardous mercury wastes.
Counter Anion Effects on PEDOT Properties and Implications on Photosystem I Incorporation
Authors: Lowery William , Jennings Kane , Cliffel David E
Published: November 2022

As energy consumption increases in tandem with the global warming crisis, the need for cleaner, renewable energy is at an all-time high. Inspired by nature’s billion-year-old process for energy production, biohybrid solar approaches have been shown to hold much promise in many aspects that are required in renewable energy. By leveraging Photosystem I (PSI), a key protein of the electron transport chain in photosynthesis, it is possible to hijack the electrons to perform an array of light-driven processes. In many areas of PSI research, conductive polymers are employed to wire the protein so that electrons can be directed to and from the reaction centers along favorable paths. Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is commonly used in these applications as it is water soluble and thus compatible with PSI. Electro-polymerization allows for direct contact of the PEDOT with an electrode surface; however, electropolymerized PEDOT:PSS is mechanically unstable. Limited research has been conducted to demonstrate the effects of other counter anions on PEDOT properties and their implications on the incorporation of PSI into a hybrid device. In this work, we describe the methodologies employed to synthesize and characterize PEDOT thin films with varying counter anions. Our findings indicate that the counter anion during the electropolymerization process affects morphology, charge transfer kinetics, and optical properties of the resulting film. Coupling these observations to the photoactivity of PEDOT-PSI hybrid films, we provide explanations for the varied performance based upon fundamental understandings of chemical and electrochemical phenomena.
Redox Potentials in Ionic Liquids: Anomalous Behavior?
Authors: Renfro Chloe Anne , McDaniel Jesse
Published: November 2022

Characterizing redox potentials in ionic liquids us essential for expanding the use of these electrolytes for electrochemical application. In particular, solvation energies of the different redox species (e.g. radical ions) determine the observed solvent-dependent trends in redox activity. In this regard, ionic liquids are fundamentally distinct from dipolar, molecular liquids in that solvation proceeds by entirely different physical mechanisms. Recently, it has been suggested that the unique ion arrangement of ionic liquids leads to dramatic deviations from Born theory in ion solvation. This conclusion was made from the theoretical assumptions of linear and homogenous response with a monopole approximation. We explore these theoretical approximations through a comparison to free energy calculations from atomistic and explicitly polarizable molecular dynamics simulations of a model ion in the prototypical ionic liquid BMIM/BF4. We find that a sharp peak in the susceptibility around 1 Å-1 is heavily influenced by the atomistic modeling and does not translate to significant free energy anomalies sans the monopole approximation. Furthermore, we show that ionic liquids largely can be approximated through linear response theory with satisfactory accuracy, although the continuum approximation does not adequately describe the system. We also explore the kinetics through the reorganization energy and observe similar trends.
(Invited) Developing Universal Sensing Strategies-Combining Functional Nucleic Acids with Photoelectrochemical and Electrochemical Signal Transduction
Authors: Soleymani Leyla , Pandey Richa , Victorious Amanda , Saha Sudip , Sakib Sadman , Zhang Zijie , Li Yingfu , Zhitomirsky Igor
Published: November 2022

Biosensors combine biorecognition with signal transduction for analyzing biologically-relevant analytes. Nucleic acids are powerful building blocks for biosensors and are used both for biorecognition and facilitating signal transduction. In this talk, we will show that functional nucleic acids can be specifically engineered for electrochemical signal transduction. We develop both aptamers and DNAzymes that are designed for electrochemical signal transduction. Electrochemical biosensors relying on functional nucleic acids are used herein to detect bacterial and viral infectious diseases in native clinical samples such as saliva and urine.

In addition to electrochemical signal transduction, we show that nucleic acids serve as powerful tools in photoelectrochemical signal transduction. We use double stranded DNA for biorecognition and for serving as a nano-ruler for tuning the separation between a photoelectrochemical label and the electrode surface. This allows us to switch the signal transduction capability of the system between signal-on and signal-off. Additionally, engineering functional nucleic acids for photoelectrochemical signal transduction, enabled us to develop a new class of pathogen biosensors. These biosensors are used in direct analysis of bacteria in water.
Towards Sensing of Breast Cancer Biomarkers: Engineering Glucose Dehydrogenase As an Estrogenic Regulated Protein
Authors: Cai Rong , Ajo-Franklin Caroline
Published: November 2022

Breast cancer is the second leading cause of cancer-related death in women. Approximately 50% of mortalities arise from estrogen receptor (ER)-positive tumors.[1] The major therapeutics for breast cancer are estrogen antagonists, like tamoxifen. Closely monitoring the antagonist in a patient would increase the efficacy of endocrine therapeutics while alleviating side effects during treatment. However, existing methods such as routine immunohistochemistry cannot effectively monitor estrogen antagonists because of their low throughput and high cost. To address these issues, we have devised a bioelectronic sensor of estrogen antagonists by grafting ER to the point of care (POC) glucometer.

Glucometers use a test strip containing glucose dehydrogenase (GDH), an enzyme that reacts with glucose in blood droplets and generates electric signals. To obtain an estrogenic regulated GDH, we inserted the ligand-binding domain of ER at all the 456 amino acids of the GDH. More than 7000 colonies were screened to identify the allosteric insertion sites globally. We find that the estrogenic regulated GDH can electrochemically detect a series of ER modulators as low as 1 nM with ≥40% dynamic range. Successful engineering of the classical glucose dehydrogenase yields a self-power antagonist sensor and establishes a platform for designing personalized diagnostics in a POC fashion.

[1] Torre, Lindsey A., et al. "Ovarian cancer statistics, 2018." CA: a cancer journal for clinicians 68.4 (2018): 284-296.
(Digital Presentation) Point-of-Care Diagnostic Device for Na/K Urinalysis
Authors: Frazier Kelvin M. , Bender Brian F. , Julien Glynis
Published: November 2022

The Centers for Disease Control and Prevention (CDC) reports 47% of adults in the United States have hypertension [1]. Dietary risks constitute the largest disease risk factor in the US [2], whereby the largest single contributor to that risk is high dietary sodium intake [3].The World Health Organization (WHO) recommends that individuals reduce sodium (Na) and increase potassium (K) intake to lower blood pressure and improve cardiovascular health [4,5]. Emerging research has shown that urinary Na/K ratio is more strongly related to blood pressure, cardiovascular disease, and stroke than Na and K considered separately [6]. Urine Na guided dietary guidance enhances the ability to monitor sodium reduction and blood pressure [7]. Manual collection for chronic urine testing is too burdensome a process for practical everyday use. We have developed an accurate biosensor capable of being easily integrated into users’ daily routine for real-time and fully automated longitudinal Na/K analysis.

Reference

[1] Centers for Disease Control and Prevention, (2021),https://www.cdc.gov/bloodpressure/facts.htm#:~

:text=Nearly%20half%20of%20adults%20in,are%20taking%20medication%20for%20hypertension.

[2] The US Burden of Disease Collaborators; A.H., Mokdad, JAMA, 319(14),1444-1472 (2018).

[3] GBD 2017 Diet Collaborators, The Lancet, 393(10184), 1958-1972 (2019).

[4] WHO Guideline Sodium intake for adults and children. Geneva: World Health Organization (WHO); 2012.

[5] WHO Guideline Potassium intake for adults and children. Geneva: World Health Organization (WHO); 2012.

[6] T. Iwahori; K. Miura; H. Ueshima; S. Tanaka-Mizuno; Q. Chan; H. Arima; A. R. Dyer; P. Elliott; J. Stamler, Hypertens Res, 42(10), 1590-1598 (2019).

[7] T. Takada; M. Imamoto; S. Sasaki; T. Azuma; J. Miyashita; M. Hayashi; S. Fukuma; S. Fukuhara, Hypertens Res, 41(7), 524-530 (2018).

Figure 1 (A) Urinalysis system installed in a urinal that can catch a stream of urine in real-time. (B) Biosensor cyclic voltammetry curve of human urine.

Figure 1
(Digital Presentation) Rapid and Oxygen-Insensitive Electrochemical Immunoassay for Detection and Staging of Prostate Cancer
Authors: Mandal Tanushree , Dhanapalamudiyanselage Lasangi , Rusling James , Leech Donal
Published: November 2022

Prostate cancer (PCa) is the most common cancer among men diagnosed worldwide. The conventional non-invasive test for detection and staging of prostate cancer include prostate specific antigen (PSA) test which often can give false positives and is unable to distinguish between aggressive and indolent stages of PCa. This results in doing unnecessary invasive tests like digital rectal examination (DRE), biopsy etc., which only gives further anxiety to patients. Here we describe a rapid and oxygen-insensitive microfluidic immunoassay for on-line capture and precise detection of potential prostate cancer protein biomarkers. Measurement of a panel of biomarkers will help in not only diagnosing the PCa precisely but may also help in staging the cancer.

The microfluidic system includes protein capture from serum using a sandwich ELISA arrangement and signal-transducing poly-horseradish peroxidase (poly-HRP) enzyme labels on an 8-electrode screen-printed carbon array. A major challenge in using these screen-printed electrode arrays is the estimation of the electrochemical surface area (ECSA) of electrodes because the current signal is proportional to ECSA and variability in the electrode surface areas generate variability in the corresponding currents. We show that normalization of electrode responses having different surface areas can be achieved using in-situ experimental methods and that the normalization methods can improve the precision of the immunoassay. Another challenge in electrochemical immunoassay systems is the interference of oxygen using the mediator hydroquinone1. A range of osmium polypyridyl complexes were studied to find the best mediator that is not affected by oxygen.

Using an optimized mediator and a simple method to estimate carbon electrode surface area, immunoassays can be designed with improved detection characteristics.

(1) Dhanapala, L.; Jones, A. L.; Czarnecki, P.; Rusling, J. F. Sub-Zeptomole Detection of Biomarker Proteins Using a Microfluidic Immunoarray with Nanostructured Sensors. Anal. Chem.
2020, 92 (12), 8021–8025. ttps://doi.org/10.1021/acs.analchem.0c01507.
(Invited) Engineering Color, Pattern, and Texture: From Nature to Materials
Authors: Deravi Leila
Published: November 2022

Biologically inspired optical materials have garnered attention for development of next-generation coatings, color-changing garments, and interactive/adaptive displays. While biological systems employ tightly coupled chemical, mechanical, and/or electrical controls to achieve changes in color, pattern, and texture with relatively low input energy, engineered systems typically provide less comprehensive function and have significant power requirements due to the limitations of off-the-shelf materials available for manufacturing. The stark differences in performance between bio-inspired, engineered materials and their sources of inspiration necessitate a re-evaluation of the approaches used to build systems designed to emulate biology. In this talk, I will highlight how adaptive display systems in nature have inspired emerging technologies like wearable multispectral light sensors and discuss important considerations for the design and development of future optical and photonic material systems
(Digital Presentation) Ultraviolet CMOS Image-Sensor Embedded with Blue-Light Emitting Quantum-Dots for Analysing Air Environment Analysis
Authors: Jung Uihyeon , Park Jun-seong , Shim Tae-Hun , Park Jea-gun
Published: November 2022

Air pollution contains sulfur dioxide (SO2) of 31.1%, nitrogen dioxide (NO2) of 27.2%, carbon oxide (COx) of 16.8%, and mineral particles of 6.3% according to the ministry of environment, Korea. Since air pollution has been harmfully affecting the health of people, the importance of controlling gas concentration and air pollution have been increased greatly and socially. To measure those gases the conventional gas detectors used by ultraviolet (UV) absorption method cannot display the image for total distribution of the gas and use public in daily life. In addition, the gas detectors used mainly at coal-fired power plant are installed in the chimney and a length of detecting probe in a detector is about 1 to 2 meters, which analyze quantitatively the gas passing through the hole with a diameter of 5-10 cm. Furthermore, since the conventional gas detectors measure only a small amount of gas coming out from chimney and their accuracies are not precise, thus, the more precise method is required for measuring the emitted gas quantitatively. In this study, therefore, we propose ultraviolet CMOS image sensor (UV-CIS) which can detect NO2 and SO2 gases quantitatively to enhance the sensitivity in detecting such gases. In particular, we investigated the characteristics of UV-CIS. We fabricated the UV-CIS embedded with blue-light emitting QD films. The structure of the UV-CIS consists of blue QDs film and blue color filter placed on conventional Si-CIS. The fabricated UV-CIS demonstrated much higher sensitivity in detecting both NO2 and SO2 gases at whole range of concentrations than conventional CIS. In particular, the sensitivity of the UV-CIS increased 1.9 times higher in detecting NO2 and 9.4 times higher in detecting SO2 than conventional CIS, respectively. It was conformed that the QD film converted UV into visible light through energy-down-conversion mechanism, which led to enhancing a sensitivity to UV light in CIS. Finally, we present energy-down-conversion characteristics of QDs synthesized, UV absorption characteristics of NO2 and SO2 gases, and the mechanism on sensing UV-light of UV-CIS to analyze an air environment.
Microfluidic Device with Room Temperature Ionic Liquids for Detecting Low Concentrations of CO2
Authors: Kaaliveetil Sreerag , Lee Yun-Yang , Li Zhenglong , Cheng Yu-Hsuan , Gurkan Burcu E , Basuray Sagnik
Published: November 2022

In this work we report the use of a gas sensor that can be used in inline configuration for applications like organ-on-a-chip. The key element of the device is a microfluidic channel with a thickness of 140 μm and width of 500 μm. This microfluidic channel is sandwiched between a top and bottom substrate, each substrate containing microelectrodes making this a non-planar interdigitated microelectrode (NP-IμE) configuration. Room temperature ionic liquids (RTILs) are used as electrolyte in the microfluidic channel. Due to the dimensions of the microfluidic channel only low volume of RTILs are required as electrolyte. RTILs can be tuned to selectively capture specific gases. This in addition to other favourable properties such as wide electrochemical window, thermal stability and negligible vapor pressure makes it a good candidate as the selective electrolyte in electrochemical gas sensor. The use of NP-IμE makes the electric field penetrate through the channel. This allows us to register the perturbations in signal caused by absorption of CO2 from the entire cross-section of the channel, thereby increasing the sensitivity of the device (as compared to a planar architecture). 1-ethyl-3-methylimidazolium 2-cyanopyrolide ([EMIM][2-CNpyr]) was used as the RTIL, as it has been shown to be a good sorbent of CO2 with high capacity at low partial pressures due to its chemical affinity. The RTILs exposed to different concentrations of CO2 was injected into the microfluidic channel. Cyclic Voltammetry (CV), Differential pulse voltammetry (DPV) and Electrochemical impedance spectroscopy (EIS) experiments were done using our microfluidic device. During the CV and DPV experiments, RTIL exposed to CO2 shows a reduction peak (of CO2). This along with the changes in EIS spectrum (Nyquist plot) can be used to detect the presence of CO2. We used CO2 as a test gas to analyse the sensitivity of our microfluidic device combined with RTIL. In future we will be using this same setup to sense biomarker gases and other toxic gases by changing the RTIL and tuning its affinity towards the target analytes.
Multi-Modal Stand-Off Detection of Plastics for Sorting Application
Authors: Zhao Yaoli , Chakraborty Patatri , Maheshkar Vaishali , Dantu Karthik , Stavinski Nicholas , Velarde Luis , Thundat Thomas
Published: November 2022

Plastics are extremely valuable to our society and are widely used in many industries such as food, beverage, textile, healthcare, automotive, aerospace, construction, agriculture, oil, etc. Since plastics do not degrade easily with time, the discarded plastics pose a grave environmental problem. Only less than 10% of plastics is recycled in the US. Therefore, there is an urgent need to increase the recycling of plastic products. At present, sorting of plastic waste is carried out manually which is time consuming, costly and manual labor intensive. To address this problem, a novel multi-modal sensor platform capable of improving the accuracy of automated sorting of various plastics by using molecular identification has been developed. This multimodal technique of standoff photothermal-photoacoustic detection is a combination of mid-infrared (MIR) photo-thermal spectroscopy and photoacoustic spectroscopy for characterizing surfaces. Since MIR is free of overtones, this region is known as the molecular fingerprint region. In this technique, the plastic surface is illuminated with a pulsed laser beam from a tunable quantum cascade laser (QCL). The photothermal detection is accomplished by collecting the scattered light from the plastic surface which contains the molecular vibration spectrum of the sample. A silicon bi-material microcantilever, fabricated by depositing a thin metal film on one of its sides is used as a sensitive uncooled infrared detector. Monitoring the bi-material cantilever bending as a function of illumination wavelength provides the IR absorption spectrum of the plastic material. Simultaneously, the photoacoustic signal generated by the absorption of light is monitored by a sensitive microphone. A highly sensitive microfabricated acoustic resonator is used for collecting the photoacoustic signal. Monitoring the microphone response as a function of wavelength produces photoacoustic spectrum (PAS) of the sample. This non-destructive characterization technique will help in enhancing the quality of plastic sorting process at materials recovery facilities and other industries by making the process inexpensive and time efficient.
(Digital Presentation) Bismuth and Transition Metal-Doped Bismuth Nanoparticles As Electrochemical Biosensors
Authors: Zheng Weiran , Lee Lawrence Yoon Suk
Published: November 2022

Current non-enzymatic electrochemical biosensors rely heavily on transition metal-based nanomaterials, such as Pt, Ni, Co, and Cu, for molecule adsorption and charge transfer. Although high performance (sensitivity and selectivity) was usually demonstrated, these elements are generally toxic, making them less applicable for wearable/in vivo sensors.

Two general strategies are approached to address such drawbacks: minimizing their usage without sacrificing the activity and searching for other elements with lower toxicity. In this study, we demonstrated that the overlooked bismuth nanoparticles (NPs) could be used for non-enzymatic electrochemical glucose sensing with comparable performance [1]. Using a laser ablation approach (see Figure 1A), stabilizer-free Bi NPs (~10 nm diameter) were prepared, showing amperometric sensitivity of 127 µA mM−1 cm−2. The synthesis approach also enabled the one-step surface doping of the Bi NPs, producing Ni and Co-doped Bi NPs with an atomic doping ratio of ~10%, and led to further sensitivity boost to 677 and 2326 µA mM−1 cm−2 (see Figure 1B). Kinetic analysis revealed that the oxidation of Bi(III) to Bi(V) species was the key to enabling glucose electrooxidation on Bi NPs. Such results demonstrate the vast potential of the overlooked bismuth in electrochemical biosensing.

Figure 1 (A) Top: illustration of the laser ablation approach of preparing Bi and metal-doped Bi NPs; Bottom: TEM images of as-prepared Bi NPs and Co-Bi NPs; (B) Amperometric correlation between glucose concentration and the current density using Bi NPs and Co-Bi NPs as sensors.

Reference:

Zheng, W.; Li, Y.; Lee, L. Y. S., Bismuth and metal-doped bismuth nanoparticles produced by laser ablation for electrochemical glucose sensing, Sens. Actuators, B
2022, 357, 131334.

Figure 1
Hydrogen Sensor with 3D Printed BaCe0.6Zr0.3Y0.1O3-α electrolyte for High-Temperature Applications
Authors: Hinojo Antonio , Lujan Enric Lujan , Colominas Sergi , Abella Jordi
Published: November 2022

Fusion energy is considered a promising source of energy for the near future. The most efficient reaction for that purpose is the fusion of deuterium and tritium, two hydrogen isotopes, to release helium, neutrons and energy. To assure the correct operation of this technology, new online devices able to monitor hydrogen isotopes will be required.

Electrochemical sensors based on solid-state proton conductor ceramics can be used for that purpose. These materials have attracted significant interest because of their chemical and physical durability, especially at elevated temperatures. These electrolytes are perovskite-type materials with electrical carriers, positive holes, excess electrons and oxide ion vacancies. In previous work [1], amperometric hydrogen sensors based on BaCe0.6Zr0.3Y0.1O3-α (BCZY) electrolyte have been developed and tested in hydrogen atmospheres obtaining good results. These prototypes were constructed using 13 mm BCZY disks obtained by uniaxial pressure.

In the present work, hydrogen sensors based on BCZY were constructed and evaluated in amperometric mode. The BCZY powder was disk-shaped using uniaxial pressure and 3D printing. Sensors were constructed as follows: first, sintered disks were platinized using platinum ink. Then, disks were sealed with a glass binder to alumina tubes. This way, the external face of the disk acted as a working electrode (WE) and the inner part of the sensor as a counter electrode (CE). 3D printed disks were fabricated using a Delta WASP 2040 ceramic 3D printer. For that, the ceramic powder was mixed with PEG400 and water until a viscous paste was obtained. Once green bodies were dried, they were heated for debinding and sintering using an optimized thermal program to reduce porosity. XRD (for crystallographic phases) and SEM (for microstructural defects and sintering) were used for the 3D printed and uniaxial pressed sintered disks characterization. The amperometric response of sensors constructed with both electrolytes (the uniaxially pressed and the 3D printed disks) was compared.

[1] A. Hinojo, I. Soriano, J. Abellà, S. Colominas, Evaluation of High-Temperature Hydrogen Sensors Based on BaCe0.6Zr0.3Y0.1O3-α and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-α Perovskites for Industrial Applications, Sensors. 20 (2020) 7258. https://doi.org/10.3390/s20247258.
AFM and Electrochemical Analysis of Different Biomolecules Using Npy-Specific Aptamer Modified Electrodes
Authors: Martinez Lyza M , Lopez Luis F. , Cunci Lisandro
Published: November 2022

Neurotransmitters and neuropeptides are chemical signals in the brain that produce responses or functions throughout the organism. Measurements of neurotransmitters are important to understand some mechanisms of how they are released off the cell. Different biomolecules can be measured with gold (Au) electrodes because it is a ductile and malleable metal that can detect small changes and can be easily modified. In this work, we use Neuropeptide Y (NPY) specific aptamer to modify the electrodes to take advantage of the binding with NPY molecules that produce conformational changes. We also study Dopamine (DA) and Norepinephrine (NE) because they corelease with NPY and we can monitor the electrochemical difference between these biomolecules. Those modifications and detection can be monitored using Electrochemical Impedance Spectroscopy (EIS) to understand the adsorption properties of molecules that stick to the surface of the electrode and Atomic Force Microscopy (AFM) to measure the topography of the electrodes before and after the aptamer modification. Electrochemical results showed that the capacitance of the Au electrode decreases at higher concentrations of NPY. AFM results showed small changes on the surface of the Au electrodes with the different modifications due to the roughness of the surface. The results obtained give us a better understanding of the use of these techniques for the monitoring of biomolecules.
Electrochemical Sensing of Cortisol in Human Saliva and Serum Using DNA-Steroid Conjugation with a Versatile DNA Nanostructure Sensor
Authors: Gurukandure Asanka , Ortiz Kacey G. , Karimov Rashad R. , Easley Christopher J.
Published: November 2022

Having a generalizable point of care (POC) method for clinically relevant biomolecules would greatly enhance healthcare management and disease diagnosis. Recently our group developed a novel DNA nanostructure architecture for versatile detection of analytes which is generalizable for assaying several small molecules and their larger protein binding partners (e.g. antibodies) in human serum. The DNA nanostructure is built through on-electrode enzymatic ligation of three oligos for electrode attachment, anchor binding, and electrochemical signaling. In this study, we developed an economical synthetic approach for making oligonucleotide-steroid conjugates, and we explored the capability of these DNA nanostructure sensors for small molecule/steroid detection.

Cortisol is a steroid hormone secreted by the hypothalamic-pituitary-adrenal system in response to the body’s stress level. As the main stress hormone, it controls processes such as immune, adrenal, circulatory, and metabolic. Moreover, anomalies of cortisol levels can result in serious conditions such as Addison’s disease, Cushing’s syndrome, and adrenal insufficiencies. Every year, 120,000 deaths are attributed, in part, to elevated levels of stress. To minimize these issues, a simplified method for cortisol sensing is vital. In this study, we conjugated cortisol to amine-tagged DNA and used the conjugates in our sensors. Anti-cortisol antibodies induced a 67% signal drop, validating conjugation. A calibration curve for cortisol showed a limit of detection of 800 pM and a dynamic range of 1 – 100 nM. The sensor was validated in saliva and human serum samples using the gold standard method, ELISA. Changing cortisol levels in two human patients' saliva samples were successfully detected after several collection times throughout a single day. As a potential point-of-care (POC) detection device, our novel cortisol biosensor could detect the hormone in human serum and saliva samples within 6 minutes.
(Invited) Soft Wearable Biosensors and Bioelectronics for Human Healthcare
Authors: Yeo W. Hong Hong
Published: November 2022

In this talk, Dr. Yeo will discuss the fundamental study in soft materials, flexible mechanics, nanomanufacturing, machine learning, and system packaging to develop nanomembrane-based intelligent soft wearable biosensors and bioelectronics. He will also talk about how fundamental science and knowledge can be applied to create various types of wearable soft sensors, circuits, and integrated bioelectronics. Afterward, he will share application examples of the wearable soft system as a portable health monitoring device, disease diagnostic device, therapeutic system, and human-machine interface system. Details of a device design, manufacturing, optimization, signal processing, and classification will be shared at high levels.
(Digital Presentation) Fully Integrated Strain-Neutralized 2D Transistors
Authors: Williams Chris , Ameri Shideh Kabiri
Published: November 2022

As performant and well-established as conventional silicon-based electronics have become, the era of wearable electronics and the Internet-of-Things has created a demand for robust electronic devices that can conform to the surfaces of the human body. Whereas the mechanical mismatch between rigid silicon electronics and the human body represents a fundamental limit to conventional non-invasive health sensing, wearable electronics and electrodes that can conform to the microscopic features of the skin1,2 can circumvent most of the motion artifacts inherent to conventional, rigid sensing devices, and facilitate continuous health monitoring as is required for modern, more proactive healthcare. Unfortunately, without addressing this fundamental mechanical incompatibility, devices that leverage the high density of transistors available in rigid silicon-based integrated circuits are handicapped by how well they can maintain contact with the body, and consequently are prone to failure at the sensor-circuit interface.

The extraordinary properties of two-dimensional materials pose a unique opportunity for addressing this mechanical mismatch. Their unusual mechanical strength combined with their ultimate thinness, optical transparency, and favorable electronic transport properties3 makes them ideal candidates for the next generation of highly conformable wearable electronics free of the constraints of a rigid silicon circuit board—however, minimizing local strain in the vicinity of the active devices to ensure reliable operation remains a priority. Using a design informed by finite element method (FEM) simulations, our proposed strain-neutralizing 2D transistors are configured to resist applied strains on the order of the 30% strains human skin can withstand by redistributing strain away from active regions. Tight binding simulations of the transistor channels helps with further compensation of residual strain in the active regions, alongside careful consideration of materials and device architecture during fabrication. Together, these considerations help realize the possibility of fully integrated strain-neutralized 2D transistors compatible with state-of-the-art conformable wearable sensors.

[1]S. Kabiri Ameri et al., “Graphene electronic tattoo sensors,” ACS Nano, 11, 7634–7641, 2017.

[2] S. Kabiri Ameri et al., “Imperceptible electrooculography graphene sensor system for human–robot interface”, npj 2D Materials and Applications, 2, 1-7, 2018.

[3] A. H. Castro Neto, F. Guinea, N. M. R. Peres, K. S. Novoselov, and A. K. Geim, “The electronic properties of graphene,” Rev. Mod. Phys., vol. 81, no. 1, pp. 109–162, Jan. 2009, doi: 10.1103/RevModPhys.81.109.
Neuropeptide Y Detection Using an Aptamer-Modifed Microelectrode Together with Methylene Blue As a Redox Probe
Authors: Fernandez-Vega Lauren , Cunci Lisandro , Vazquez Yolimar , Melendez-Rodriguez Dorian Enid
Published: November 2022

Neuroscience research has been growing fast over the last few years. Particularly the knowledge about neurotransmitters has increased over the past 50 years, impacting the understanding of many neurological disorders, including depression, schizophrenia, Parkinson's disease, and Alzheimer's disease. Still, there is a lack of knowledge about neuropeptides' liberation and action, and most of their function is assumed by indirect measurements. Neuropeptides are classified as non-electroactive molecules, making them difficult to track; consequently, the design of an analytical technique for their measurements is imperative. Neuropeptide Y (NPY) is the most abundant neuropeptide in the brain. It is associated with a wide range of biological processes and conditions, including depression, anxiety, obesity, alcoholism, mood changes, feeding behavior, and post-traumatic stress disorder (PTSD), among others. Currently, there is no method for NPY measurement in high temporal and spatial resolution in the brain. Therefore, we proposed the design of a biological sensor to understand the mechanism in which NPY is involved. This research is focused on electrochemical methods to detect and measure NPY based on an affinity-mediated strategy. An aptamer, a short single-stranded DNA with high affinity by NPY, was attached to a Pt surface of a microelectrode, taking advantage of the affinity between Pt and a thiol group in the aptamer structure. Then, to amplify the electrochemical signal, a redox molecule such as methylene blue (MB) was conjugated to the aptamer to allow rapid measurements of NPY levels in real-time. Real-time techniques such as cyclic voltammetry and square wave voltammetry (SWV) were explored to detect NPY in artificial Cerebrospinal Fluid (aCSF). Due to MB having a characteristic signal in both techniques, we successfully measured NPY concentration in aCSF (pH = 7.4). A change in current was observed as the NPY molecules interacted with the aptamer affecting the MB electrochemical signal and producing a "signal-off" sensor. These results allow us to obtain a calibration curve that will be used as an initial platform to perform Fast Scan Cyclic Voltammetry (FSCV) measurements to increase the time resolution in our measurements.