Battery-powered Instrument Research Articles

The Development of a Real-Time Recombinase-Aid Amplification Assay for Rapid Detection of African Swine Fever Virus.

African swine fever (ASF), caused by the African swine fever virus (ASFV), is an acute, deadly, infectious disease of domestic pigs and wild boars and has a tremendous negative socioeconomic impact on the swine industry. ASF is a notifiable disease to the World Organization for Animal Health (OIE). Currently, no effective vaccine or treatment against ASF is available. Early detection and rapid diagnosis are potentially significant to control ASF spread with the emerging ASFV mutant strains and non-classical symptoms. In this study, we developed a real-time recombinase-aid amplification (RAA) assay to detect the ASFV genome rapidly. Thirty samples were detected using commercial lysis buffer for DNA extraction and equipped with a portable testing instrument. The results showed that the sensitivity of RAA was 103 copies per reaction at 95% probability in 9 min at 39°C. The method was universally specific for three strains of ASFV, and there was no cross-reaction with other pathogens, including foot-and-mouth disease virus (FMDV), classical swine fever virus (CSFV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus 2 (PCV2), pseudorabies virus (PRV), and porcine parvovirus (PPV). The coefficient of variation (C.V) of repetitive experiments was 0%, and the coincidence rate was 100% compared to the real-time qPCR. 123 field samples were detected by the real-time RAA assay, and the results showed that the clinical coincidence rate of the real-time RAA assay was 98% compared to the real-time qPCR assay. The advantages of this method were as follows: the extraction of DNA can be performed on site, the DNA template is directly used, a small battery-powered instrument is easily available, and the on-site diagnostic process is finished within an hour. These suggest that this assay could be used to detect different genotypes of ASFV and play a vital role in the control of ASF.

Baseline Air Monitoring of Fine Particulate Matter and Trace Elements in Ontario’s Far North, Canada

Large mineral deposits have been discovered in Ontario’s Far North and are being considered for further development. Particulate matter and trace elements can be emitted from potential mining activities and these air pollutants are associated with health risks and harmful to the sensitive ecosystem. An air monitoring station, powered by solar panels and a wind turbine, was established in this near-pristine area to monitor baseline levels of fine particulate matter (PM2.5) and trace elements downwind of a proposed mine site. Levels of PM2.5 and trace elements observed from 2015 to 2018 were much lower than measurements observed in southern Ontario, suggesting minimal influence of primary emissions in the study area. One episodic PM2.5 event in July 2015 was attributable to wildfire emissions in northern Ontario. Only 8 out of the 31 target elements were detected in 25% or more of the samples. Good correlations among As, Se, Pb, and Sb, between Mn and Fe, as well as between Ce and La indicated they originated from long-range atmospheric transport from the south. Ontario’s Ambient Air Quality Criteria were not exceeded for any target air pollutants. Four years of air measurements filled the data gap of baseline information in this near-pristine study area and can be used to assess impacts of potential mining activities in the future. Field operations during this study period indicated that the battery-powered air instruments and meteorological sensors worked well in the harsh environment of Ontario’s Far North even in cold winter months. The field experiences gained in this study can be applied to future air monitoring activities in harsh environments where no direct power supply is available and site access is limited.

Graphene oxide nanocomposites based room temperature gas sensors: A review

Over the last few decades, various volatile organic compounds (VOCs) have been widely used in the processing of building materials and this practice adversely affected the environment i.e. both indoor and outdoor air quality. A cost-effective solution for detecting a wide range of VOCs by sensing approaches includes chemiresistive, optical and electrochemical techniques. Room temperature (RT) chemiresistive gas sensors are next-generation technologies desirable for self-powered or battery-powered instruments utilized in monitoring emissions that are associated with indoor/outdoor air pollution and industrial processes. In this review, a state-of-the-art overview of chemiresistive gas sensors is provided based on their attractive analytical characteristics such as high sensitivity, selectivity, reproducibility, rapid assay time and low fabrication cost. The review mainly discusses the recent advancement and advantages of graphene oxide (GO) nanocomposites-based chemiresistive gas sensors and various factors affecting their sensing performance at RT. Besides, the sensing mechanisms of GO nanocomposites-based chemiresistive gas sensors derived using metals, transition metal oxides (TMOs) and polymers were discussed. Finally, the challenges and future perspectives of GO nanocomposites-based RT chemiresistive gas sensors are addressed.

New Methods for Personal Exposure Monitoring for Airborne Particles.

Airborne particles have been associated with a range of adverse cardiopulmonary outcomes, which has driven its monitoring at stationary central sites throughout the world. Individual exposures, however, can differ substantially from concentrations measured at central sites due to spatial variability across a region and sources unique to the individual, such as cooking or cleaning in homes, traffic emissions during commutes, and widely varying sources encountered at work. Personal monitoring with small, battery-powered instruments enables the measurement of an individual's exposure as they go about their daily activities. Personal monitoring can substantially reduce exposure misclassification and improve the power to detect relationships between particulate pollution and adverse health outcomes. By partitioning exposures to known locations and sources, it may be possible to account for variable toxicity of different sources. This review outlines recent advances in the field of personal exposure assessment for particulate pollution. Advances in battery technology have improved the feasibility of 24-h monitoring, providing the ability to more completely attribute exposures to microenvironment (e.g., work, home, commute). New metrics to evaluate the relationship between particulate matter and health are also being considered, including particle number concentration, particle composition measures, and particle oxidative load. Such metrics provide opportunities to develop more precise associations between airborne particles and health and may provide opportunities for more effective regulations.

Batch-injection analysis with amperometric detection of the DPPH radical for evaluation of antioxidant capacity

This work proposes the application of batch-injection analysis with amperometric detection to determine the antioxidant capacity of real samples based on the measurement of DPPH radical consumption. The efficient concentration or EC50 value corresponds to the concentration of sample or standard required to scavenge 50% DPPH radicals. For the accurate determination of EC50, samples were incubated with DPPH radical for 1h because many polyphenolic compounds typically found in plants and responsible for the antioxidant activity exhibit slow kinetics. The BIA system with amperometric detection using a glassy-carbon electrode presented high precision (RSD=0.7%, n=12), low detection limit (1μmolL−1) and selective detection of DPPH (free of interferences from antioxidants). These contributed to low detection limits for the antioxidant (0.015 and 0.19μmolL−1 for gallic acid and butylated hydroxytoluene, respectively). Moreover, BIA methods show great promise for portable analysis because battery-powered instrumentation (electronic micropipette and potentiostats) is commercially available.

A Handheld Point-of-Care Genomic Diagnostic System

The rapid detection and identification of infectious disease pathogens is a critical need for healthcare in both developed and developing countries. As we gain more insight into the genomic basis of pathogen infectivity and drug resistance, point-of-care nucleic acid testing will likely become an important tool for global health. In this paper, we present an inexpensive, handheld, battery-powered instrument designed to enable pathogen genotyping in the developing world. Our Microfluidic Biomolecular Amplification Reader (µBAR) represents the convergence of molecular biology, microfluidics, optics, and electronics technology. The µBAR is capable of carrying out isothermal nucleic acid amplification assays with real-time fluorescence readout at a fraction of the cost of conventional benchtop thermocyclers. Additionally, the µBAR features cell phone data connectivity and GPS sample geotagging which can enable epidemiological surveying and remote healthcare delivery. The µBAR controls assay temperature through an integrated resistive heater and monitors real-time fluorescence signals from 60 individual reaction chambers using LEDs and phototransistors. Assays are carried out on PDMS disposable microfluidic cartridges which require no external power for sample loading. We characterize the fluorescence detection limits, heater uniformity, and battery life of the instrument. As a proof-of-principle, we demonstrate the detection of the HIV-1 integrase gene with the µBAR using the Loop-Mediated Isothermal Amplification (LAMP) assay. Although we focus on the detection of purified DNA here, LAMP has previously been demonstrated with a range of clinical samples, and our eventual goal is to develop a microfluidic device which includes on-chip sample preparation from raw samples. The µBAR is based entirely around open source hardware and software, and in the accompanying online supplement we present a full set of schematics, bill of materials, PCB layouts, CAD drawings, and source code for the µBAR instrument with the goal of spurring further innovation toward low-cost genetic diagnostics.

Development of an In Situ pH Calibrator in Deep Sea Environments

The pH Calibrator is an instrument for in situ calibration and measurement of chemical species (pH) in aqueous fluids at elevated pressure. The calibration device consists of two interactive systems: a data-logging sensor system and an automated fluid de- livery system. The solid-state pH sensor array is sealed in a flow cell to decrease measurement response time. The automated fluid de- livery system consists of a pump and process control valves, which intermittently deliver seawater samples for measurement. Following measurement cycles, the pH buffer solutions are drawn into the sensor cell to perform two-point calibration. Here, we describe the initial steps in its conversion from a battery-powered instrument for short-term application into a unit that can be used to take full advantage of cabled-powered observatories that will soon be coming online at a number of locations in marine environments. Accordingly, we made use of the continuous power supply and TCP/IP network capability intrinsic to the Monterey Accelerated Research System (MARS)-cabled ocean observatory, Monterey Bay, CA, to reconfigure the unit in anticipation of future seafloor deployments. The flow through system has been further optimized to reduce dead volume effects in the calibration process, while the mechanical system can now better tolerate increases in fluid discharge pressure and flow rate for long-term operations. Furthermore, the sensor head is now equipped with a novel valve to enhance operations in hydrothermal diffuse flow environments. To gain full access to the MARS-cabled observatory, the dc-dc power converter module and Ethernet to serial module are integrated to the electronics. The pH Calibrator has passed the wet node simulator tests in a seawater tank at the Monterey Bay Aquarium Research Institute, moving the project closer to fulfilling long-term objectives for marine studies.

Aerostat-lofted instrument and sampling method for determination of emissions from open area sources

An aerostat-borne instrument and sampling method was developed to characterize air samples from area sources, such as emissions from open burning. The 10 kg battery-powered instrument system, termed “the Flyer”, is lofted with a helium-filled aerostat of 4 m nominal diameter and maneuvered by means of one or two tethers. The Flyer can be configured variously for continuous CO 2 monitoring, batch sampling of semi-volatile organic compounds (SVOCs), volatile organic compounds (VOCs), black carbon, metals, and PM by size. The samplers are controlled by a trigger circuit to avoid unnecessary dilution from background sampling when not within the source plume. The aerostat/Flyer method was demonstrated by sampling emissions from open burning (OB) and open detonation (OD) of military ordnance. A carbon balance approach was used to derive emission factors that showed excellent agreement with published values.

Actuation of elastomeric microvalves in point-of-care settings using handheld, battery-powered instrumentation

Although advanced fluid handling using elastomeric valves is useful for a variety of lab-on-a-chip procedures, their operation has traditionally relied on external laboratory infrastructure (such as gas tanks, computers, and ground electricity). This dependence has held back the use of elastomeric microvalves for point-of-care settings. Here, we demonstrate that microfabricated microvalves, via liquid-filled control channels, can be actuated using only a handheld instrument powered by a 9 V battery. This setup can achieve on-off fluid control with fast response times, coordinated switching of multiple valves, and operation of a biological assay. In the future, this technique may enable the widely used elastomeric microvalves (made by multilayer soft lithography) to be increasingly adopted for portable sensors and lab-on-a-chip systems.

Wideband digital low-frequency radio receiver

A wideband digital low-frequency radio receiver for scientific applications is described. The portable battery-powered instrument has the capability to record electric field strengths in the frequency range from ∼4 Hz to ∼400 kHz with a sampling frequency of 1 MHz, an amplitude resolution of ∼35 µV and a timing accuracy of ∼12 ns whilst performing continuous digital waveform recordings for several days. The instrument strictly follows a modular design such that it can be extended to higher frequencies and timing accuracy when the corresponding digital technology becomes available. The low-cost radio receiver can be developed into an interferometric network by synchronizing individual radio receivers to map the low-frequency radio sky. The first measurements of atmospheric electric fields are carried out at Exmoor National Park in Southwest England to illustrate the capabilities of the novel instrument.

Therapeutic Dose from a Pyroelectric Electron Accelerator

Simple heating of pyroelectric crystals has been used as the basis for compact sources of X rays, electrons, ions and neutrons. We report on the evaluation of the feasibility of using a portable pyroelectric electron accelerator to deliver a therapeutic dose to tissue. Such a device could be mass produced as a handheld, battery-powered instrument. Experiments were conducted with several crystal sizes in which the crystal was heated inside a vacuum chamber and the emitted electrons were allowed to penetrate a thin beryllium window into the surrounding air. A Faraday cup was used to count the number of electrons that exited the window. The energy of these electrons was determined by measuring the energy spectrum of the X rays that resulted from the electron interactions with the Faraday cup. Based on these measurements, the dose that this source could deliver to tissue was calculated using Monte Carlo calculations. It was found that 10(13) electrons with a peak energy of the order of 100 keV were emitted from the beryllium window and could deliver a dose of 1664 Gy to a 2-cm-diameter, 110-microm-deep region of tissue located 1.5 cm from the window with air between the window and the tissue. This dose level is high enough to consider this technology for medical applications in which shallow energy deposition is beneficial.

Electronic battery-powered hearing instrument, and method for operating such a hearing instrument

An electronic battery-powered hearing instrument (10) comprises a first power supply terminal (1) and a second power supply terminal (2) arranged to contact a battery (3), a rectifier circuit (6) for providing a positive supply voltage ( U p) and a negative supply voltage ( U n) regardless of a polarity of the battery (3) relative to the first and second power supply terminal (2), primary function means (7) arranged to provide at least one drive signal ( U d) to a drive circuit (20) for driving an electroacoustic conversion means (13) by controlling electrical valve means (14, 15, 16, 17). The drive circuit (20) is electrically connected to the first power supply terminal (1) and to the second power supply terminal (2), and the electrical valve means (14, 15, 16, 17) are polarity-independent, that is, they are able to operate regardless of the polarity of the voltage applied to their terminals. As a result, the current path from the battery (3) to the electroacoustic conversion means (13) and back again comprises at the most two electrical valve means (14, 15, 16, 17), e.g. transistors, minimising voltage drop and power loss.

Development of Portable Immunoassay Instrument for Screening of PCBs in Transformer Oil

A rapid and simple procedure for the detection of PCBs in transformer oil, using an immunoassay implemented on a handheld battery-powered instrument, is described. Monoclonal anti-PCB antibody is simultaneously mixed with a gold-labeled secondary antibody and oil extract, and then flowed through a disposable cell. The absorbance change in the disposable cell, due to accumulation of the gold-labeled secondary antibody, provides a measure of PCBs present in the oil extract. Measurements of transformer oil using both the immunoassay and HRGC-HRMS showed a good correlation over the range of 0.1 mg/kg to 8.4 mg/kg total PCBs. Eighty six transformer oil samples were screened using the immunoassay at a cutoff concentration of 0.4 mg/kg total PCBs with no false positives and no false negatives observed. The same result was obtained when the cut off concentration was raised to 5.0 mg/kg. The results suggest that the described immunoassay can provide a fast and effective alternative to other procedures, such as GC-ECD for screening transformer oil for PCBs.

On-line coupling of a microelectrode array equipped poly(dimethylsiloxane) microchip with an integrated graphite electrospray emitter for electrospray ionisation mass spectrometry

A novel method for the manufacturing of microchips for on-chip combinations of electrochemistry (EC) and sheathless electrospray ionisation mass spectrometry (ESI-MS) is described. The technique, which does not require access to clean-room facilities, is based on the incorporation of an array of gold microcoil electrodes into a poly(dimethylsiloxane)(PDMS) microflow channel equipped with an integrated graphite based sheathless ESI emitter. Electrochemical measurements, which were employed to determine the electroactive area of the electrodes and to test the microchips, show that the manufacturing process was reproducible and that the important interelectrode distance in the electrochemical cell could to be adequately controlled. The EC-ESI-MS device was evaluated based on the ESI-MS detection of the oxidation products of dopamine. The results demonstrate that the present on-chip approach enables full potentiostatic control of the electrochemical cell and the attainment of very short transfer times between the electrochemical cell and the electrospray emitter. The transfer times were 0.6 and 1.2 s for flow rates of 1.0 and 0.5 microL min(-1), respectively, while the electrochemical conversion efficiency of the electrochemical cell was found to be 30% at a flow rate of 0.5 microL min(-1). To decouple the electrochemical cell from the ESI-MS high voltage and to increase the user-friendliness, the on-line electrochemistry-ESI-MS experiments were performed using a wireless Bluetooth battery-powered instrument with the chip floating at the potential induced by the ESI high voltage. The described on-chip EC-ESI-MS device can be used for fundamental electrochemical investigations as well as for applications based on the use of electrochemically controlled sample pretreatment, preconcentration and ionisation steps prior to ESI-MS.

Bulk-micromachined submicroliter-volume PCR chip with very rapid thermal response and low power consumption.

The current paper describes the design, fabrication, and testing of a micromachined submicroliter-volume polymerase chain reaction (PCR) chip with a fast thermal response and very low power consumption. The chip consists of a bulk-micromachined Si component and hot-embossed poly(methyl methacrylate)(PMMA) component. The Si component contains an integral microheater and temperature sensor on a thermally well-isolated membrane, while the PMMA component contains a submicroliter-volume PCR chamber, valves, and channels. The micro hot membrane under the submicroliter-volume chamber is a silicon oxide/silicon nitride/silicon oxide (O/N/O) diaphragm with a thickness of 1.9 microm, resulting in a very low thermal mass. In experiments, the proposed chip only required 45 mW to heat the reaction chamber to 92 degrees C, the denaturation temperature of DNA, plus the heating and cooling rates are about 80 degrees C s(-1) and 60 degrees C s(-1), respectively. We validated, from the fluorescence results from DNA stained with SYBR Green I, that the proposed chip amplified the DNA from vector clone, containing tumor suppressor gene BRCA 1 (127 base pairs at 11th exon), after 30 thermal cycles of 3 s, 5 s, and 5 s at 92 degrees C, 55 degrees C, and 72 degrees C, respectively, in a 200 nL-volume chamber. As for specificity of DNA products, owing to difficulty in analyzing the very small volume PCR results from the micro chip, we vicariously employed the larger volume PCR products after cycling with the same sustaining temperatures as with the micro chip but with much slower ramping rates (3.3 degrees C s(-1) when rising, 2.5 degrees C s(-1) when cooling) within circa 20 minutes on a commercial PCR machine and confirmed the specificity to BRCA 1 (127 base pairs) with agarose gel electrophoresis. Accordingly, the fabricated micro chip demonstrated a very low power consumption and rapid thermal response, both of which are crucial to the development of a fully integrated and battery-powered instrument for a lab-on-a-chip DNA analysis.

Ultrathin crossroads: Is smaller better?

Ultrathin crossroads: Is smaller better?

Rapid spectrophotometric measurements of total bilirubin in intact and hemolyzed neonatal blood: a feasibility study.

Conventional methods for measuring the total bilirubin concentration in blood require the use of serum or plasma, but physically separating red blood cells from plasma by centrifugation is a time-consuming and potentially dangerous process that does not lend itself to rapid, near-patient testing. Therefore, we have sought to determine whether spectrophotometric measurements of total bilirubin concentration are feasible in unaltered whole blood. We modified an Hb-Quick hemoglobinometer (Avox Systems, Inc., San Antonio, TX), a relatively new, portable, battery-powered instrument that uses disposable cuvettes and a reagentless system to measure total hemoglobin in nonhemolyzed, whole blood. The prototype consisted of an Hb-Quick equipped with light-emitting diodes with emissions at five different wavelengths to measure total bilirubin and total hemoglobin. Using blood samples from neonates with suspected hyperbilirubinemia, we made measurements on plasma from centrifuged samples and on hemolyzed and nonhemolyzed aliquots of the same blood samples. In the first series of experiments, we compared the Unistat bilirubinometer's readings with the prototype's measurements of bilirubin in plasma. There was a close linear correlation between the prototype's measurements and those of the reference instrument (slope=1.01, r(2)=0.991). Subsequently, we used the prototype's measurements on plasma as the reference method and compared them with readings on hemolyzed and nonhemolyzed aliquots of each sample. Readings on hemolyzed and nonhemolyzed aliquots were significantly correlated with the measurements in plasma, but the regression lines did not have a slope of 1. However, when the measurements on hemolyzed and nonhemolyzed blood were scaled appropriately to compensate for the fact that red cells "dilute" the bilirubin in plasma, the correlation coefficients improved, and there was then a 1:1 relationship between the measurements in whole blood and plasma. These preliminary findings demonstrate the feasibility of developing a portable instrument to measure total bilirubin in unaltered whole blood. The advantages of this method are speed, elimination of centrifugation or other sample preparation, and instrument portability. The disadvantage is that the concentration units are unconventional, i.e., milligrams of bilirubin per volume of whole blood. However, the instrument can be programmed to display the total bilirubin concentration in traditional units, e.g., milligrams of bilirubin per volume of plasma.

General purpose, field-portable cell-based biosensor platform

There are several groups of researchers developing cell-based biosensors for chemical and biological warfare agents based on electrophysiologic monitoring of cells. In order to transition such sensors from the laboratory to the field, a general-purpose hardware and software platform is required. This paper describes the design, implementation, and field-testing of such a system, consisting of cell-transport and data acquisition instruments. The cell-transport module is a self-contained, battery-powered instrument that allows various types of cell-based modules to be maintained at a preset temperature and ambient CO 2 level while in transit or in the field. The data acquisition module provides 32 channels of action potential amplification, filtering, and real-time data streaming to a laptop computer. At present, detailed analysis of the data acquired is carried out off-line, but sufficient computing power is available in the data acquisition module to enable the most useful algorithms to eventually be run real-time in the field. Both modules have sufficient internal power to permit realistic field-testing, such as the example presented in this paper.

Thermal modelling and characterisation of micropower chemoresistive silicon sensors

There is considerable interest in the development of low-cost, low-power resistive sensors for possible application in hand-held gas monitors. In this paper we describe the fabrication of a high-temperature, resistive sensor using silicon microtechnology which lies on a sub-micron thick membrane with an embedded platinum resistance heater. A thermal model of this micro-hotplate is constructed and compared with its observed behaviour. The microsensor can be operated at temperatures of up to 600°C and has a low d.c. power consumption per sensor of 40 mW at 300°C. As the thermal time-constant of the microsensor is only about 5 ms, its average power consumption can be reduced by a factor of at least ten through an a.c. mode of operation, thus making a single device or even an array device suitable for battery-powered instruments.

Design of a silicon microsensor array device for gas analysis

This paper describes the design of a silicon-based microsensor array for application in gas or odour monitoring. Individual sensor cells consist of both lateral and vertical electrode pairs to measure film conductance and/or capacitance. The fabrication process involves standard silicon technologies to integrate a platinum or nickel-iron heater below the sensor cells. A simulation of the device gives a thermal response time of only 60 ms and an ultra low power loss of about 50 mW at 400°C per sensor. This compares well with experimental values observed on a similar device. The process technology is suitable for both the deposition of organic materials (e.g. conducting polymers) and inorganic materials (e.g. semiconducting oxides). A scheme of the tranducer interface circuity is also provided, and could be used in a portable battery-powered instrument.