Miniaturized thermal acoustic gas sensor based on a CMOS microhotplate and MEMS microphone.

We present a miniaturised thermal acoustic gas sensor, fabricated using a CMOS microhotplate and MEMS microphone. The sensing mechanism is based on the detection of changes in the thermal acoustic conversion efficiency which is dependent on the physical properties of the gas. An active sensing element, consisting of a MEMS microphone, is used to detect the target gas while a reference element is used for acoustic noise compensation. Compared to current photoacoustic gas sensors, our sensor requires neither the use of gas-encapsulated microphones, nor that of optical filters. In addition, it has all the benefits of CMOS technology, including production scalability, low cost and miniaturization. Here we demonstrate its application for CO[Formula: see text] gas detection. The sensor could be used for gas leak detection, for example, in an industrial plant.

One-step SYBR green-based real-time RT-PCR assay for detection of foot-and-mouth disease virus circulating in India.

Rapid, sensitive, and reliable laboratory detection of foot-and-mouth disease virus (FMDV) infection is essential for containing and controlling virus infection in any geographical area. In this report a SYBR green-based 3Dpol-specific one-step real-time RT-PCR (rRT-PCR) assay was developed for the pan-serotype detection of FMDV in India. The detection limit of the SYBR green-based rRT-PCR was 10-2 TCID50/50 µl, which is 10 times more sensitive than the traditional agarose gel electrophoresis-based RT-multiplex PCR (RT-mPCR). The standard curve exhibited a linear range across 8-log10 units of viral RNA dilution. The reproducibility and specificity of this assay were reasonably high suggesting that the 3Dpol-specific SYBR green rRT-PCR could detect FMDV genome specifically and with little run-to-run variation. The new 3Dpol-specific SYBR green rRT-PCR assay was evaluated alongside the established RT-mPCR using the archived FMDV isolates and clinical field samples from suspected FMD outbreaks. A perfect concordance was observed between the new rRT-PCR and the traditional RT-mPCR on viral RNA in the archived FMDV cell culture isolates tested. Furthermore, 73% of FMDV-suspected clinical samples were detected positive through the 3Dpol-specific SYBR green rRT-PCR, while the detection rate through the traditional RT-mPCR was 57%. Therefore, the SYBR green-based 3Dpol-specific one-step rRT-PCR could be considered as a valuable assay with higher diagnostic sensitivity to complement the routine assays that are being used for FMD virus diagnosis in India.

A highly stable, nanotube-enhanced, CMOS-MEMS thermal emitter for mid-IR gas sensing.

The gas sensor market is growing fast, driven by many socioeconomic and industrial factors. Mid-infrared (MIR) gas sensors offer excellent performance for an increasing number of sensing applications in healthcare, smart homes, and the automotive sector. Having access to low-cost, miniaturized, energy efficient light sources is of critical importance for the monolithic integration of MIR sensors. Here, we present an on-chip broadband thermal MIR source fabricated by combining a complementary metal oxide semiconductor (CMOS) micro-hotplate with a dielectric-encapsulated carbon nanotube (CNT) blackbody layer. The micro-hotplate was used during fabrication as a micro-reactor to facilitate high temperature (>700 [Formula: see text]C) growth of the CNT layer and also for post-growth thermal annealing. We demonstrate, for the first time, stable extended operation in air of devices with a dielectric-encapsulated CNT layer at heater temperatures above 600 [Formula: see text]C. The demonstrated devices exhibit almost unitary emissivity across the entire MIR spectrum, offering an ideal solution for low-cost, highly-integrated MIR spectroscopy for the Internet of Things.

Genetic characterization of foot-and-mouth disease virus serotype O isolates collected during 2014-2018 revealed dominance of O/ME-SA/Ind2001e and the emergence of a novel lineage in India.

Foot-and-mouth disease (FMD) is endemic in India with a preponderance of outbreaks caused by FMD virus (FMDV) serotype O. Out of the 11 global topotypes of serotype O, only ME-SA topotype has been reported in the country so far. Lineage O/ME-SA/Ind2001 and O/ME-SA/PanAsia are documented as the most dominant ones in terms of the number of outbreaks caused by them. To understand the distribution of topotype/lineages in India and their antigenic behaviour during the year 2014-2018, a total of 286 FMDV serotype O viral isolates were sequence determined at the VP1 region, and 109 isolates were characterized antigenically. All the isolates grouped in the ME-SA topotype, being distributed in lineage O/ME-SA/Ind2001 (within sub-lineages O/ME-SA/Ind2001d and O/ME-SA/Ind2001e), and a new group designated here as O/ME-SA/2018 cluster. The sub-lineage O/ME-SA/Ind2001e reported for the first time in India during the year 2015, replaced sub-lineage O/ME-SA/Ind2001d gradually, which was dominating since 2008. During the years 2014-2018, the sub-lineage O/ME-SA/Ind2001e was found to be the most predominant one whose mean evolutionary rate was observed to be faster than that of the sub-lineage O/ME-SA/Ind2001d. The codon sites 45 and 85 of VP1 were found to be under diversifying selection in a large proportion of trees. The common ancestor predicted for sub-lineages O/ME-SA/Ind2001e and O/ME-SA/2018 dates back to 2012 and 2016, respectively. The sustenance and spread of the new O/ME-SA/2018 cluster need to be assessed by continued surveillance. The Indian vaccine strain O/INDR2/1975 was found to provide adequate antigenic coverage to the emerging and prevalent serotype O lineages. The trait association tests showed frequent virus exchange among different states, which could be an important confounder in the region-specific assessment of effectiveness of FMD control programme.

Crosstalk Analysis of a CMOS Single Membrane Thermopile Detector Array.

We present a new experimental technique to characterise the crosstalk of a thermopile-based thermal imager, based on bi-directional electrical heating of thermopile elements. The new technique provides a significantly simpler and more reliable method to determine the crosstalk, compared to a more complex experimental setup with a laser source. The technique is used to characterise a novel single-chip array, fabricated on a single dielectric membrane. We propose a theoretical model to simulate the crosstalk, which shows good agreement with the experimental results. Our results allow a better understanding of the thermal effects in these devices, which are at the center of a rising market of industrial and consumer applications.

The burden of submicroscopic and asymptomatic malaria in India revealed from epidemiology studies at three varied transmission sites in India.

Malaria in India, while decreasing, remains a serious public health problem, and the contribution of submicroscopic and asymptomatic infections to its persistence is poorly understood. We conducted community surveys and clinic studies at three sites in India differing in their eco-epidemiologies: Chennai (Tamil Nadu), Nadiad (Gujarat), and Rourkela (Odisha), during 2012-2015. A total of 6,645 subject blood samples were collected for Plasmodium diagnosis by microscopy and PCR, and an extensive clinical questionnaire completed. Malaria prevalence ranged from 3-8% by PCR in community surveys (24 infections in Chennai, 56 in Nadiad, 101 in Rourkela), with Plasmodium vivax dominating in Chennai (70.8%) and Nadiad (67.9%), and Plasmodium falciparum in Rourkela (77.3%). A proportional high burden of asymptomatic and submicroscopic infections was detected in community surveys in Chennai (71% and 71%, respectively, 17 infections for both) and Rourkela (64% and 31%, 65 and 31 infections, respectively). In clinic studies, a proportional high burden of infections was identified as submicroscopic in Rourkela (45%, 42 infections) and Chennai (19%, 42 infections). In the community surveys, anemia and fever were significantly more common among microscopic than submicroscopic infections. Exploratory spatial analysis identified a number of potential malaria hotspots at all three sites. There is a considerable burden of submicroscopic and asymptomatic malaria in malarious regions in India, which may act as a reservoir with implications for malaria elimination strategies.

Smart CMOS mid-infrared sensor array.

We present a novel single-chip thermopile sensor array for mid-infrared room temperature imaging. The array is fabricated on a single complementary metal-oxide-semiconductor (CMOS) dielectric membrane, composed of single-crystal silicon (Si) p+ and n+ elements, and standard CMOS tungsten metal layers for thermopile cold junction heatsinking, significantly reducing the chip size and simplifying its processing. We demonstrate a 16×16 pixel device with 34 V/W responsivity and enhanced optical absorption in the 8-14 µm waveband, with a suitable performance for gesture recognition and people-counting applications. Our simple, low-cost sensor is an attractive on-chip array for a variety of applications in the mid-infrared spectral region.

Dengue, chikungunya, and scrub typhus are important etiologies of non-malarial febrile illness in Rourkela, Odisha, India.

BACKGROUND: We conducted a diagnostic surveillance study to identify Plasmodium, dengue virus, chikungunya virus, and Orientia tsutsugamushi infections among febrile patients who underwent triage for malaria in the outpatient department at Ispat General Hospital, Rourkela, Odisha, India. METHODS: Febrile patients were enrolled from January 2016-January 2017. Blood smears and small volumes or vacutainers of blood were collected from study participants to carry out diagnostic assays. Malaria was diagnosed using rapid diagnostic tests (RDT), microscopy, and PCR. Dengue, chikungunya, and scrub typhus infections were identified using rapid diagnostic test kits and ELISA. RESULTS: Nine hundred and fifty-four patients were prospectively enrolled in our study. The majority of patients were male (58.4%) and more than 15 years of age (66.4%). All 954 enrollees underwent additional testing for malaria; a subset of enrollees (293/954) that had larger volumes of plasma available was also tested for dengue, chikungunya and scrub typhus by either RDT or ELISA or both tests. Fifty-four of 954 patients (5.7%) were positive for malaria by RDT, or microscopy, or PCR. Seventy-four of 293 patients (25.3%) tested positive for dengue by either RDT or ELISA, and 17 of 293 patients (5.8%) tested positive for chikungunya-specific IgM by either ELISA or RDT. Ten of 287 patients tested (3.5%) were positive for scrub typhus by ELISA specific for scrub typhus IgM. Seventeen patients among 290 (5.9%) with results for ≥3 infections tested positive for more than one infection. Patients with scrub typhus and chikungunya had high rates of co-infection: of the 10 patients positive for scrub typhus, six were positive for dengue (p = 0.009), and five of 17 patients positive for chikungunya (by RDT or ELISA) were also diagnosed with malaria (p < 0.001). CONCLUSIONS: Dengue, chikungunya and scrub typhus are important etiologies of non-malarial febrile illness in Rourkela, Odisha, and comorbidity should be considered. Routine febrile illness surveillance is required to accurately establish the prevalence of these infections in this region, to offer timely treatment, and to implement appropriate methods of control.

Sensitivity Enhancement of Silicon-on-Insulator CMOS MEMS Thermal Hot-Film Flow Sensors by Minimizing Membrane Conductive Heat Losses.

Minimizing conductive heat losses in Micro-Electro-Mechanical-Systems (MEMS) thermal (hot-film) flow sensors is the key to minimize the sensors' power consumption and maximize their sensitivity. Through a comprehensive review of literature on MEMS thermal (calorimetric, time of flight, hot-film/hot-film) flow sensors published during the last two decades, we establish that for curtailing conductive heat losses in the sensors, researchers have either used low thermal conductivity substrate materials or, as a more effective solution, created low thermal conductivity membranes under the heaters/hot-films. However, no systematic experimental study exists that investigates the effect of membrane shape, membrane size, heater/hot-film length and M e m b r a n e (size) to H e a t e r (hot-film length) Ratio (MHR) on sensors' conductive heat losses. Therefore, in this paper we have provided experimental evidence of dependence of conductive heat losses in membrane based MEMS hot-film flow sensors on MHR by using eight MEMS hot-film flow sensors, fabricated in a 1 µm silicon-on-insulator (SOI) CMOS foundry, that are thermally isolated by square and circular membranes. Experimental results demonstrate that: (a) thermal resistance of both square and circular membrane hot-film sensors increases with increasing MHR, and (b) conduction losses in square membrane based hot-film flow sensors are lower than the sensors having circular membrane. The difference (or gain) in thermal resistance of square membrane hot-film flow sensors viz-a-viz the sensors on circular membrane, however, decreases with increasing MHR. At MHR = 2, this difference is 5.2%, which reduces to 3.0% and 2.6% at MHR = 3 and MHR = 4, respectively. The study establishes that for membrane based SOI CMOS MEMS hot-film sensors, the optimum MHR is 3.35 for square membranes and 3.30 for circular membranes, beyond which the gain in sensors' thermal efficiency (thermal resistance) is not economical due to the associated sharp increase in the sensors' (membrane) size, which makes sensors more expensive as well as fragile. This paper hence, provides a key guideline to MEMS researchers for designing the square and circular membranes-supported micro-machined thermal (hot-film) flow sensors that are thermally most-efficient, mechanically robust and economically viable.

Characterizing Antibody Responses to Plasmodium vivax and Plasmodium falciparum Antigens in India Using Genome-Scale Protein Microarrays.

Understanding naturally acquired immune responses to Plasmodium in India is key to improving malaria surveillance and diagnostic tools. Here we describe serological profiling of immune responses at three sites in India by probing protein microarrays consisting of 515 Plasmodium vivax and 500 Plasmodium falciparum proteins with 353 plasma samples. A total of 236 malaria-positive (symptomatic and asymptomatic) plasma samples and 117 malaria-negative samples were collected at three field sites in Raurkela, Nadiad, and Chennai. Indian samples showed significant seroreactivity to 265 P. vivax and 373 P. falciparum antigens, but overall seroreactivity to P. vivax antigens was lower compared to P. falciparum antigens. We identified the most immunogenic antigens of both Plasmodium species that were recognized at all three sites in India, as well as P. falciparum antigens that were associated with asymptomatic malaria. This is the first genome-scale analysis of serological responses to the two major species of malaria parasite in India. The range of immune responses characterized in different endemic settings argues for targeted surveillance approaches tailored to the diverse epidemiology of malaria across the world.

Virility does not imply immensity: Testis size, accessory gland size and ejaculate depletion pattern do not evolve in response to experimental manipulation of sex ratio in Drosophila melanogaster.

Sperm competition theory predicts that with increase in sperm competition, males either invest more in reproductive organ(s) and/or improve ejaculate investment. We test this idea using experimental evolution in Drosophila melanogaster. We maintained replicate populations of Drosophila melanogaster under male (M) and female (F) biased sex ratio regimes for more than a hundred generations with the result that males from the M regime evolved higher sperm competitive abilities relative to males from the F regime. In the present study, we measured the testes and the accessory gland size of virgin and singly mated males from the M and F regimes. The M and F males do not differ in either testis or accessory gland size. Additionally, ejaculate investment is not different in the M and F males, as measured by reduction in testis and accessory gland sizes. Thus, contrary to theoretical prediction and evidence from other species, we found that evolved differences in sperm competitive ability are not necessarily due to evolution of testis/accessory gland size or strategic ejaculate investment in these populations.

An SOI CMOS-Based Multi-Sensor MEMS Chip for Fluidic Applications.

An SOI CMOS multi-sensor MEMS chip, which can simultaneously measure temperature, pressure and flow rate, has been reported. The multi-sensor chip has been designed keeping in view the requirements of researchers interested in experimental fluid dynamics. The chip contains ten thermodiodes (temperature sensors), a piezoresistive-type pressure sensor and nine hot film-based flow rate sensors fabricated within the oxide layer of the SOI wafers. The silicon dioxide layers with embedded sensors are relieved from the substrate as membranes with the help of a single DRIE step after chip fabrication from a commercial CMOS foundry. Very dense sensor packing per unit area of the chip has been enabled by using technologies/processes like SOI, CMOS and DRIE. Independent apparatuses were used for the characterization of each sensor. With a drive current of 10 µA-0.1 µA, the thermodiodes exhibited sensitivities of 1.41 mV/°C-1.79 mV/°C in the range 20-300 °C. The sensitivity of the pressure sensor was 0.0686 mV/(Vexcit kPa) with a non-linearity of 0.25% between 0 and 69 kPa above ambient pressure. Packaged in a micro-channel, the flow rate sensor has a linearized sensitivity of 17.3 mV/(L/min)-0.1 in the tested range of 0-4.7 L/min. The multi-sensor chip can be used for simultaneous measurement of fluid pressure, temperature and flow rate in fluidic experiments and aerospace/automotive/biomedical/process industries.

Low Power Resistive Oxygen Sensor Based on Sonochemical SrTi0.6Fe0.4O2.8 (STFO40).

The current paper reports on a sonochemical synthesis method for manufacturing nanostructured (typical grain size of 50 nm) SrTi0.6Fe0.4O2.8 (Sono-STFO40) powder. This powder is characterized using X ray-diffraction (XRD), Mössbauer spectroscopy and Scanning Electron Microscopy (SEM), and results are compared with commercially available SrTi0.4Fe0.6O2.8 (STFO60) powder. In order to manufacture resistive oxygen sensors, both Sono-STFO40 and STFO60 are deposited, by dip-pen nanolithography (DPN) method, on an SOI (Silicon-on-Insulator) micro-hotplate, employing a tungsten heater embedded within a dielectric membrane. Oxygen detection tests are performed in both dry (RH = 0%) and humid (RH = 60%) nitrogen atmosphere, varying oxygen concentrations between 1% and 16% (v/v), at a constant heater temperature of 650 °C. The oxygen sensor, based on the Sono-STFO40 sensing layer, shows good sensitivity, low power consumption (80 mW), and short response time (25 s). These performance are comparable to those exhibited by state-of-the-art O2 sensors based on STFO60, thus proving Sono-STFO40 to be a material suitable for oxygen detection in harsh environments.

Evolution of mate-harm, longevity and behaviour in male fruit flies subjected to different levels of interlocus conflict.

BACKGROUND: Interlocus conflict predicts (a) evolution of traits, beneficial to males but detrimental to females and (b) evolution of aging and life-span under the influence of the cost of bearing these traits. However, there are very few empirical investigations shedding light on these predictions. Those that do address these issues, mostly reported response of male reproductive traits or the lack of it and do not address the life-history consequence of such evolution. Here, we test both the above mentioned predictions using experimental evolution on replicate populations of Drosophila melanogaster. We present responses observed after >45 generations of altered levels of interlocus conflict (generated by varying the operational sex ratio). RESULTS: Males from the male biased (high conflict, M-regime) regime evolved higher spontaneous locomotor activity and courtship frequency. Females exposed to these males were found to have higher mortality rate. Males from the female biased regime (low conflict, F-regime) did not evolve altered courtship frequency and activity. However, progeny production of females continuously exposed to F-males was significantly higher than the progeny production of females exposed to M-males indicating that the F-males are relatively benign towards their mates. We found that males from male biased regime lived shorter compared to males from the female biased regime. CONCLUSION: F-males (evolving under lower levels of sexual conflict) evolved decreased mate harming ability indicating the cost of maintenance of the suit of traits that cause mate-harm. The M-males (evolving under higher levels sexual conflict) caused higher female mortality indicating that they had evolved increased mate harming ability, possibly as a by product of increased reproduction related activity. There was a correlated evolution of life-history of the M and F-males. M-regime males lived shorter compared to the males from F-regime, possibly due to the cost of investing more in reproductive traits. In combination, these results suggest that male reproductive traits and life-history traits can evolve in response to the altered levels of interlocus sexual conflict.

Sperm competitive ability evolves in response to experimental alteration of operational sex ratio.

In naturally polygamous organisms such as Drosophila, sperm competitive ability is one of the most important components of male fitness and is expected to evolve in response to varying degrees of male-male competition. Several studies have documented the existence of ample genetic variation in sperm competitive ability of males. However, many experimental evolution studies have found sperm competitive ability to be unresponsive to selection. Even direct selection for increased sperm competitive ability has failed to yield any measurable changes. Here we report the evolution of sperm competitive ability (sperm defense-P1, offense-P2) in a set of replicate populations of Drosophila melanogaster subjected to altered levels of male-male competition (generated by varying the operational sex ratio) for 55-60 generations. Males from populations with female-biased operational sex ratio evolved reduced P1 and P2, without any measurable change in the male reproductive behavior. Males in the male-biased regime evolved increased P1, but there was no significant change in P2. Increase in P1 was associated with an increase in copulation duration, possibly indicating greater ejaculate investment by these males. This study is one of the few to provide empirical evidence for the evolution of sperm competitive ability of males under different levels of male-male competition.

dSir2 in the adult fat body, but not in muscles, regulates life span in a diet-dependent manner.

Sir2, an evolutionarily conserved NAD(+)-dependent deacetylase, has been implicated as a key factor in mediating organismal life span. However, recent contradictory findings have brought into question the role of Sir2 and its orthologs in regulating organismal longevity. In this study, we report that Drosophila Sir2 (dSir2) in the adult fat body regulates longevity in a diet-dependent manner. We used inducible Gal4 drivers to knock down and overexpress dSir2 in a tissue-specific manner. A diet-dependent life span phenotype of dSir2 perturbations (both knockdown and overexpression) in the fat body, but not muscles, negates the effects of background genetic mutations. In addition to providing clarity to the field, our study contrasts the ability of dSir2 in two metabolic tissues to affect longevity. We also show that dSir2 knockdown abrogates fat-body dFOXO-dependent life span extension. This report highlights the importance of the interplay between genetic factors and dietary inputs in determining organismal life spans.