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Fulltext Effects of temperature, humidity, air quality and anthropic activities on the transmission of SARS-CoV-2: a systematic review protocol

Jeevananthan C, Muhamad NA, Jaafar MH, Hod R, Ab Ghani RM, Md Isa Z, et al.

BMJ Open, 2020 11 04;10(11):e039623.
PMID: 33148753 DOI: 10.1136/bmjopen-2020-039623

INTRODUCTION: The current global pandemic of the virus that emerged from Hubei province in China has caused coronavirus disease in 2019 (COVID-19), which has affected a total number of 900 036 people globally, involving 206 countries and resulted in a cumulative of 45 693 deaths worldwide as of 3 April 2020. The mode of transmission is identified through airdrops from patients' body fluids such as during sneezing, coughing and talking. However, the relative importance of environmental effects in the transmission of the virus has not been vastly studied. In addition, the role of temperature and humidity in air-borne transmission of infection is presently still unclear. This study aims to identify the effect of temperature, humidity and air quality in the transmission of SARS-CoV-2.
METHODS AND ANALYSIS: We will systematically conduct a comprehensive literature search using various databases including PubMed, EMBASE, Scopus, CENTRAL and Google Scholar to identify potential studies. The search will be performed for any eligible articles from the earliest published articles up to latest available studies in 2020. We will include all the observational studies such as cohort case-control and cross-sectional studies that explains or measures the effects of temperature and/or humidity and/or air quality and/or anthropic activities that is associated with SARS-CoV-2. Study selection and reporting will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and Meta-Analysis of Observational Studies in Epidemiology guideline. All data will be extracted using a standardised data extraction form and quality of the studies will be assessed using the Newcastle-Ottawa Scale guideline. Descriptive and meta-analysis will be performed using a random effect model in Review Manager File.
ETHICS AND DISSEMINATION: No primary data will be collected, and thus no formal ethical approval is required. The results will be disseminated through a peer-reviewed publication and conference presentation.
PROSPERO REGISTRATION NUMBER: CRD42020176756.

Matched MeSH terms: Humidity*
Fulltext Ultra-Sensitive Humidity Sensor Based on Optical Properties of Graphene Oxide and Nano-Anatase TiO2

Ghadiry M, Gholami M, Lai CK, Ahmad H, Chong WY

PLoS One, 2016;11(4):e0153949.
PMID: 27101247 DOI: 10.1371/journal.pone.0153949

Generally, in a waveguide-based humidity sensors, increasing the relative humidity (RH) causes the cladding refractive index (RI) to increase due to cladding water absorption. However, if graphene oxide (GO) is used, a reverse phenomenon is seen due to a gap increase in graphene layers. In this paper, this interesting property is applied in order to fabricate differential humidity sensor using the difference between RI of reduced GO (rGO) and nano-anatase TiO2 in a chip. First, a new approach is proposed to prepare high quality nano-anatase TiO2 in solution form making the fabrication process simple and straightforward. Then, the resulted solutions (TiO2 and GO) are effortlessly drop casted and reduced on SU8 two channels waveguide and extensively examined against several humid conditions. Investigating the sensitivity and performance (response time) of the device, reveals a great linearity in a wide range of RH (35% to 98%) and a variation of more than 30 dB in transmitted optical power with a response time of only ~0.7 sec. The effect of coating concentration and UV treatment are studied on the performance and repeatability of the sensor and the attributed mechanisms explained. In addition, we report that using the current approach, devices with high sensitivity and very low response time of only 0.3 sec can be fabricated. Also, the proposed device was comprehensively compared with other state of the art proposed sensors in the literature and the results were promising. Since high sensitivity ~0.47dB/%RH and high dynamic performances were demonstrated, this sensor is a proper choice for biomedical applications.

Matched MeSH terms: Humidity*
Fulltext Nano-Anatase TiO₂ for High Performance Optical Humidity Sensing on Chip

Ghadiry M, Gholami M, Kong LC, Yi CW, Ahmad H, Alias Y

Sensors (Basel), 2015;16(1).
PMID: 26729115 DOI: 10.3390/s16010039

An on-chip optical humidity sensor using Nano-anatase TiO₂ coating is presented here. The coating material was prepared so that the result is in solution form, making the fabrication process quick and simple. Then, the solution was effortlessly spin-coated on an SU8 straight channel waveguide. Investigating the sensitivity and performance (response time) of the device revealed a great linearity in the wide range (35% to 98%) of relative humidity (RH). In addition, a variation of more than 14 dB in transmitted optical power was observed, with a response time of only ~0.7 s. The effect of coating concentration and UV treatment was examined on the performance and repeatability of the sensor. Interesting observations were found, and the attributed mechanisms were described. In addition, the proposed sensor was extensively compared with other state-of-the-art proposed counterparts from the literature and remarkable advantages were found. Since a high sensitivity of ~0.21 dB/%RH and high dynamic performances were demonstrated, this sensor is proposed for use in biomedical applications.

Matched MeSH terms: Humidity
Fulltext Comparative reliability studies and analysis of Au, Pd-coated Cu and Pd-doped Cu wire in microelectronics packaging

Chong Leong G, Uda H

PLoS One, 2013;8(11):e78705.
PMID: 24244344 DOI: 10.1371/journal.pone.0078705

This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (Do) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, β of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires.

Matched MeSH terms: Humidity
Meteorological multivariable approximation and prediction with classical VAR-DCC approach

Siti Mariam Norrulashikin, Fadhilah Yusof, Ibrahim Lawal Kane

Sains Malaysiana, 2018;47:409-417.

The vector autoregressive (VAR) approach is useful in many situations involving model development for multivariables
time series. VAR model was utilised in this study and applied in modelling and forecasting four meteorological variables.
The variables are n rainfall data, humidity, wind speed and temperature. However, the model failed to address the
heteroscedasticity problem found in the variables, as such, multivariate GARCH, namely, dynamic conditional correlation
(DCC) was incorporated in the VAR model to confiscate the problem of heteroscedasticity. The results showed that the use
of the VAR coupled with the recognition of time-varying variances DCC produced good forecasts over long forecasting
horizons as compared with VAR model alone.

Matched MeSH terms: Humidity
Fulltext Investigation of Surface Plasmon Resonance (SPR) in MoS2- and WS2-Protected Titanium Side-Polished Optical Fiber as a Humidity Sensor

Zakaria R, Zainuddin NAM, Leong TC, Rosli R, Rusdi MF, Harun SW, et al.

Micromachines (Basel), 2019 Jul 11;10(7).
PMID: 31336745 DOI: 10.3390/mi10070465

In this paper, we report the effects of a side-polished fiber (SPF) coated with titanium (Ti) films in different thicknesses, namely 5 nm, 13 nm, and 36 nm, protected by a thin layer of transition metal dichalcogenides (TMDCs) such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2), which provide ultra-sensitive sensor-based surface plasmon resonance (SPR) covering from the visible to mid-infrared region. The SPF deposited with Ti exhibits strong evanescent field interaction with the MoS2 and WS2, and good optical absorption, hence resulting in high-sensitivity performance. Incremental increases in the thickness of the Ti layer contribute to the enhancement of the intensity of transmission with redshift and broad spectra. The findings show that the optimum thickness of Ti with 36 nm combined with MoS2 causes weak redshifts of the longitudinal localized surface plasmon resonance (LSPR) mode, while the same thickness of Ti with WS2 causes large blueshifts. The redshifts are possibly due to a reduced plasmon-coupling effect with the excitonic region of MoS2. The observed blueshifts of the LSPR peak position are possibly due to surface modification between WS2 and Ti. Changing the relative humidity from 58% to 88% only elicited a response in Ti/MoS2. Thus, MoS2 shows more sensitivity on 36-nm thickness of Ti compared with WS2. Therefore, the proposed fiber-optic sensor with integration of 2D materials is capable of measuring humidity in any environment.

Matched MeSH terms: Humidity
Fulltext Impact of a katabatic wind event on GPS PWV measurements at Scott Base Station, Antarctica

Suparta, W., Samah, A.A., Harper, A.R.

ASM Science Journal, 2009;3(2):152-160.
MyJurnal

Katabatic winds dramatically affect the polar climate. Their activity depends on density of air and temperature in the source region. This paper presents for first time an analysis of the precipitable water vapour (PWV) variability and its relation to a katabatic event at Scott Base station, Antarctica. A significant effect in their characteristics toward calculation of a reliable user accuracy in GPS applications is addressed. Our investigations using the data between 21st and 30th of November 2002 showed that the PWV profile exhibited an irregular pattern with a maximum value of 7.38 mm (~ 6 mm on average), and was more strongly influenced by relative humidity than by wind speed activity. The dominant wind flow during this period was from the North-Northeast (blowing from the Ross Sea) with a median speed of 4.96 ms–1. The PWV was high when the temperature was between –15ºC and –11ºC. During the dates identified as a katabatic event between 21:30 UT of 28th November and 18:40 UT on 29th November, the wind blew from the Southeast-South direction (from the Ross Ice Shelf) with a maximum speed of 10.92 ms–1. The PWV increased ~1.4 mm (23%) from the mean value, indicating severe wind during this event which had pronounced effect on GPS observations.

Matched MeSH terms: Humidity
Fulltext Development of an edible coating based on chitosan-glycerol to delay ‘Berangan’ banana (Musa sapientum cv. Berangan) ripening process

Jafarizadeh Malmiri, H., Osman, A., Tan, C.P., Abdul Rahman, R.

International Food Research Journal, 2011;18(3):-.
MyJurnal

Response surface methodology (RSM) was used to optimize the concentrations of chitosan and glycerol for coating Berangan banana (Musa sapientum cv. Berangan). The effects of main edible coating components, chitosan (0.5-2.5%, w/w) and glycerol (0-2%, w/w) on weight loss, firmness, total colour difference, total soluble solids content (TSS) and titratable acidity (TA) of coated banana were studied during 10 days of storage at 26±2°C and 40-50% relative humidity. Results showed that the experimental data could be adequately fitted into a second-order polynomial model with coefficient of determination (R 2 ) ranging from 0.745 to 0.930 for all the variables studied. In general, the chitosan concentration appeared to be the most significant (P< 0.1) factor influencing all variables except for TSS. The optimum concentration of chitosan and glycerol were predicted to be 2.02% and 0.18%, respectively. Statistical assessment showed insignificant difference between experimental and predicted values.

Matched MeSH terms: Humidity
Fulltext Spatial regression with conditional autoregressive (CAR) errors for annual mean relative humidity in Peninsular Malaysia

Shitan, Mahendran, Kok, Wei Ling

Pertanika Journal of Science & Technology, 2009;17(2):-.
MyJurnal

Modelling observed meteorological elements can be useful. For instance, modelling rainfall has
been an interest for many researchers. In a previous research, trend surface analysis was used and
it was indicated that the residuals might spatially be correlated. When dealing with spatial data, any
modelling technique should take spatial correlation into consideration. Hence, in this project, fitting
of spatial regression models, with spatially correlated errors to the annual mean relative humidity
observed in Peninsular Malaysia, is illustrated. The data used in this study comprised of the annual
mean relative humidity for the year 2000-2004, observed at twenty principal meteorological stations
distributed throughout Peninsular Malaysia. The modelling process was done using the S-plus
Spatial Statistics Module. A total of twelve models were considered in this study and the selection
of the model was based on the p-value. It was found that a possible appropriate model for the
annual mean relative humidity should include an intercept and a term of the longitude as covariate,
together with a conditional autoregressive error structure. The significance of the coefficient of the
covariate and spatial parameter was established using the Likelihood Ratio Test. The usefulness
of the proposed model is that it could be used to estimate the annual mean relative humidity at
places where observations were not recorded and also for prediction. Some other potential models
incorporating the latitude covariate have also been proposed as viable alternatives.

Matched MeSH terms: Humidity
Fulltext Microclimatic performance of courtyard residential buildings in Kafanchan-Nigeria

Markus Bulus, Lim, Yaik-Wah, Malsiah Hamid

Journal of Advanced Research Design, 2017;37(1):16-25.
MyJurnal

The Climatic performance of courtyard residential buildings needs to be
investigated if the assertion that courtyard is a microclimate modifier is to be
accepted. Therefore, this study seeks to examine the microclimatic performance
of two existing courtyard residential buildings with similar characteristics in
Kafanchan-Kaduna Nigeria, -the fully enclosed courtyard residential building and
the semi-enclosed courtyard residential building. The purpose of this research is
to investigate their microclimatic performances in other to establish the best
courtyard house. This study uses measurement to achieve its aim. The tool
employed for data collection is the Hobo Weather Data Loggers (HWDL). Three
HWDL were used to collect data in the two case-study, and the third one was
placed in the outside area as a benchmark. Only air temperature and relative
humidity were measured. This study revealed a tangible difference in the
microclimatic performance of the two case-study. The fully enclosed courtyard
residential building is seen to have air temperature difference of 1 oC to 3 oC, and
the relative humidity difference of 4 % to 8 %. In conclusion, the fully enclosed
courtyard house demonstrated a more favorable microclimatic performance than
the semi-enclosed, and further simulation studies towards its optimization are
required.

Matched MeSH terms: Humidity
Fulltext Fuzzy-controlled humidity variation by Silica gel and Nitrogen gas in an atmospheric chamber

Ali Ghahraei, Nurul Amziah Md Yunus, Izhal Abdul Halin, Nasri Sulaiman

Pertanika Journal of Science & Technology, 2017;25(102):133-142.
MyJurnal

Controlled humidity environment is of significance in many scientific researches and experiments. In most laboratory-scale atmospheric chambers, an electrical temperature-based control system is used to adjust humidity. Since these chambers are not affordable in every laboratory, other low cost chambers using nitrogen gas or silica gel are used to adjust humidity. In this paper, a mechanism was developed to control the relative humidity in closed lab-scale chambers. Humidification is done by spraying water through a blower fan while de-humidification is by pumping air through silica gel as well as nitrogen gas injection. A Mamdani type fuzzy controller was designed to control the components and relative humidity. The results show the proposed system and controller can adjust and maintain relative humidity from 41% to 100% with maximum overshoot of 1% and the maximum range of error of steady state of 1.2 %.

Matched MeSH terms: Humidity
Fulltext Analysis of air humidity and temperature for post lightning circumstances

Sharifah Sakinah, Tuan Othman, Jasronita, Jasni, Mohd Nazim, Mohtar

Pertanika Journal of Science & Technology, 2017;25(102):79-86.
MyJurnal

Lightning is a natural phenomenon that generates a high electric field during thunderstorm. It has been
reported that lightning strikes amid storms can occur around 100 times per second. The atmospheric
electric field is an imperative parameter during a thunderstorm. Therefore, monitoring the electric field
and its parameters is the best way for local lightning forecast. The electric field monitoring data can
validate the accuracy of weather prediction in a local area from meteorology department or by using
equipment specially designed to measure this electric field that exists when the phenomenon of lightning occurs. In this paper, the relationship between lightning, air humidity and temperature is discussed to understand the post lightning effect on these electric parameters. Additionally, the characteristics of the parameters are observed and analysed.

Matched MeSH terms: Humidity
Fulltext Analysis of fill time and injection pressure of multiple 20 gram Parisons during injection moulding process

Najiy Rizal Suriani Rizal, Azuddin Mamat, Aidah Jumahat

Pertanika Journal of Science & Technology, 2017;25(103):233-240.
MyJurnal

In recent years, injection moulding process is one of the most advanced and efficient manufacturing processes for mass production of plastic bottles. However, a good quality of parison is difficult to achieve due to uncontrollable humidity, pressure inlet and water inlet velocity. This paper investigates the effect of using multiple mould cavities to improve the process fill time and injection pressure in the production of PET plastic bottles using MoldFlow software. The modelling of parison was developed using CATIA with the consideration of every part of the parison. MoldFlow software was used to analyse the flow of 20 g parison with different cavity numbers (1, 8, 16, 24 cavity), as well as its corresponding runner size towards its fill time and injection pressure. Other important parameters that affect the production of parison, such as melting temperature, mould temperature, atmospheric temperature and cooling time, were remained constant. The fill time required to produce 24 moulds was improved by 60% compared to using 8 mould cavity only, and this enable the production of more plastic bottles in a day. Therefore, fill time and injection pressure are two important parameters to be considered in the injection moulding process, especially to reduce parison defect and increase its production rate.

Matched MeSH terms: Humidity
Fulltext Effect of integration of oxalic acid and hot water treatments on postharvest quality of rambutan (Nephelium lappaceum L. cv. Anak Sekolah) under modified atmosphere packaging

Hafiz AFA, Keat YW, Ali A

J Food Sci Technol, 2017 Jun;54(7):2181-2185.
PMID: 28720977 DOI: 10.1007/s13197-017-2645-1

The shelf life of rambutan is often limited due to rapid water loss from the spinterns and browning of the pericarp. An integrated approach, which combined hot water treatment (HWT) (56 °C for 1 min), oxalic acid (OA) dip (10% for 10 min) and modified atmosphere packaging (MAP), was used to study their effectiveness on the quality of rambutan during storage (10 °C, 90-95% relative humidity). Significant differences were observed in rambutan quality with the combination of MAP + HWT + OA after 20 days of storage. This treatment combination resulted into better retention of firmness and colour (L and a* values) than in the control. Change in the total soluble solid content was significantly delayed however the titratable acidity showed no significant change in comparison to the control at the end of storage.

Matched MeSH terms: Humidity
Fulltext Land use conversion from peat swamp forest to oil palm agriculture greatly modifies microclimate and soil conditions

Anamulai S, Sanusi R, Zubaid A, Lechner AM, Ashton-Butt A, Azhar B

PeerJ, 2019;7:e7656.
PMID: 31632845 DOI: 10.7717/peerj.7656

Oil palm (Elaeis guineensis) agriculture is rapidly expanding and requires large areas of land in the tropics to meet the global demand for palm oil products. Land cover conversion of peat swamp forest to oil palm (large- and small-scale oil palm production) is likely to have negative impacts on microhabitat conditions. This study assessed the impact of peat swamp forest conversion to oil palm plantation on microclimate conditions and soil characteristics. The measurement of microclimate (air temperature, wind speed, light intensity and relative humidity) and soil characteristics (soil surface temperature, soil pH, soil moisture, and ground cover vegetation temperature) were compared at a peat swamp forest, smallholdings and a large-scale plantation. Results showed that the peat swamp forest was 1.5-2.3 °C cooler with significantly greater relative humidity, lower light intensities and wind speed compared to the smallholdings and large-scale plantations. Soil characteristics were also significantly different between the peat swamp forest and both types of oil palm plantations with lower soil pH, soil and ground cover vegetation surface temperatures and greater soil moisture in the peat swamp forest. These results suggest that peat swamp forests have greater ecosystem benefits compared to oil palm plantations with smallholdings agricultural approach as a promising management practice to improve microhabitat conditions. Our findings also justify the conservation of remaining peat swamp forest as it provides a refuge from harsh microclimatic conditions that characterize large plantations and smallholdings.

Matched MeSH terms: Humidity
Fulltext SmartFire: Intelligent Platform for Monitoring Fire Extinguishers and Their Building Environment

Garcia-Martin R, González-Briones A, Corchado JM

Sensors (Basel), 2019 May 25;19(10).
PMID: 31130598 DOI: 10.3390/s19102390

Due to fire protection regulations, a minimum number of fire extinguishers must be available depending on the surface area of each building, industrial establishment or workplace. There is also a set of rules that establish where the fire extinguisher should be placed: always close to the points that are most likely to be affected by a fire and where they are visible and accessible for use. Fire extinguishers are pressure devices, which means that they require maintenance operations that ensure they will function properly in the case of a fire. The purpose of manual and periodic fire extinguisher checks is to verify that their labeling, installation and condition comply with the standards. Security seals, inscriptions, hose and other seals are thoroughly checked. The state of charge (weight and pressure) of the extinguisher, the bottle of propellant gas (if available), and the state of all mechanical parts (nozzle, valves, hose, etc.) are also checked. To ensure greater safety and reduce the economic costs associated with maintaining fire extinguishers, it is necessary to develop a system that allows monitoring of their status. One of the advantages of monitoring fire extinguishers is that it will be possible to understand what external factors affect them (for example, temperature or humidity) and how they do so. For this reason, this article presents a system of soft agents that monitors the state of the extinguishers, collects a history of the state of the extinguisher and environmental factors and sends notifications if any parameter is not within the range of normal values.The results rendered by the SmartFire prototype indicate that its accuracy in calculating pressure changes is equivalent to that of a specific data acquisition system (DAS). The comparative study of the two curves (SmartFire and DAS) shows that the average error between the two curves is negligible: 8% in low pressure measurements (up to 3 bar) and 0.3% in high pressure (above 3 bar).

Matched MeSH terms: Humidity
Horizontal heat flux between urban buildings and soil and its influencing factors

Zhou H, Wang X, Li Y, Han F, Hu D

Sains Malaysiana, 2016;45:689-697.

The soil temperature near four external walls with different orientations was investigated in spring and summer. In both
seasons, the soil temperature was higher in the positions closest to the buildings, suggesting that the buildings were a
heat source for the soil surrounding them. Therefore, it could be confirmed that there was lateral heat transfer between
the soil and the buildings. Based on this, a soil heat flux plate was set between the soil and the buildings to investigate the
horizontal heat flux. The data showed diurnal variations of the horizontal heat flux in both spring and summer. In order
to determine the factors that influenced the horizontal heat flux and to provide a basis to understand its mechanism, the
correlations between the data of several meteorological factors and the horizontal heat flux were analysed. The results
showed that solar radiation was significantly correlated with the horizontal heat flux (p<0.0001) in any single season and
in the two seasons that were studied. Additionally, other meteorological factors (net radiation, air temperature, relative
humidity and soil temperature and moisture) showed strong correlations with the horizontal heat flux on a diurnal scale
only. On a seasonal time scale, the correlation might be significant (p<0.0001) as well, but the correlation coefficients
decreased too significantly, such as those for soil temperature, air temperature and relative humidity. Alternatively, the
correlation might not be significant (p>0.05), such as that for soil moisture. The stepwise regression results indicated
that the relative importance of these meteorological factors was 48.63, 21.94, 14.44, 8.12 and 6.87% for solar radiation,
soil temperature, air temperature, relative humidity and soil moisture, respectively, on a diurnal scale.

Matched MeSH terms: Humidity
Fulltext Ambient factors influencing Photovoltaic module temperature in Klang valley

Hedzlin Zainuddin, Maisarah Ismail, Nurul Hidayah Bostamam, Muhamad Mukhzani Muhamad Hanifah, Mohamad Fariz Mohamad Taib, Mohamad Zhafran Hussin

Science Letter, 2016;10(2):23-25.
MyJurnal

The study is conducted to evaluate the significance of solar irradiance, ambient temperature and relative humidity as predictors and to quantify the relative contribution of these ambient parameters as predictors for photovoltaic module temperature model. The module temperature model was developed from experimental data of mono-crystalline and poly-crystalline PV modules retrofitted on metal roof in Klang Valley. The model was developed and analyzed using Multiple Linear Regressions (MLR) and Principle Component Analysis (PCA) Techniques. Solar irradiance, ambient temperature and relative humidity have been proven to be the significant predictors for module temperature. For poly-crystalline PV module, the relative contribution of solar irradiance, ambient temperature and relative humidity are 64.28 %, 17.45 % and 12.64 % respectively. For mono-crystalline PV module, the relative contribution of solar irradiance, ambient temperature and relative humidity are 66.12 %, 17.46 % and 12.48 % respectively. Thus, there is no significant difference in terms of relative contribution of these ambient parameters towards photovoltaic module temperature between poly-crystalline and mono-crystalline PV module technologies.

Matched MeSH terms: Humidity
Fulltext Fabrication and Characterization of a CMOS-MEMS Humidity Sensor

Dennis JO, Ahmed AY, Khir MH

Sensors (Basel), 2015;15(7):16674-87.
PMID: 26184204 DOI: 10.3390/s150716674

This paper reports on the fabrication and characterization of a Complementary Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) device with embedded microheater operated at relatively elevated temperatures (40 °C to 80 °C) for the purpose of relative humidity measurement. The sensing principle is based on the change in amplitude of the device due to adsorption or desorption of humidity on the active material layer of titanium dioxide (TiO2) nanoparticles deposited on the moving plate, which results in changes in the mass of the device. The sensor has been designed and fabricated through a standard 0.35 µm CMOS process technology and post-CMOS micromachining technique has been successfully implemented to release the MEMS structures. The sensor is operated in the dynamic mode using electrothermal actuation and the output signal measured using a piezoresistive (PZR) sensor connected in a Wheatstone bridge circuit. The output voltage of the humidity sensor increases from 0.585 mV to 30.580 mV as the humidity increases from 35% RH to 95% RH. The output voltage is found to be linear from 0.585 mV to 3.250 mV as the humidity increased from 35% RH to 60% RH, with sensitivity of 0.107 mV/% RH; and again linear from 3.250 mV to 30.580 mV as the humidity level increases from 60% RH to 95% RH, with higher sensitivity of 0.781 mV/% RH. On the other hand, the sensitivity of the humidity sensor increases linearly from 0.102 mV/% RH to 0.501 mV/% RH with increase in the temperature from 40 °C to 80 °C and a maximum hysteresis of 0.87% RH is found at a relative humidity of 80%. The sensitivity is also frequency dependent, increasing from 0.500 mV/% RH at 2 Hz to reach a maximum value of 1.634 mV/% RH at a frequency of 12 Hz, then decreasing to 1.110 mV/% RH at a frequency of 20 Hz. Finally, the CMOS-MEMS humidity sensor showed comparable response, recovery, and repeatability of measurements in three cycles as compared to a standard sensor that directly measures humidity in % RH.

Matched MeSH terms: Humidity
Fulltext Air-conditioning, health and outdoor thermal comfort in some local cities

Ilyas M

Med J Malaysia, 1980 Dec;35(2):131-3.
PMID: 7266405
Matched MeSH terms: Humidity

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