Development and deployment of a microfluidic platform for water quality monitoring

There is an increasing demand for autonomous sensor devices which can provide reliable data on key water quality parameters at a higher temporal and geographical resolution than is achievable using current approaches to sampling and monitoring. Microfluidic technology, in combination with rapid and on-going developments in the area of wireless communications, has significant potential to address this demand due to a number of advantageous features which allow the development of compact, low-cost and low-powered analytical devices. Here we report on the development of a microfluidic platform for water quality monitoring. This system has been successfully applied to in-situ monitoring of phosphate in environmental and wastewater monitoring applications. We describe a number of the technical and practical issues encountered and addressed during these deployments and summarise the current status of the technology

In situ monitoring of environmental water quality using an autonomous microfluidic sensor

An autonomous microfluidic sensor for phosphate in environmental waters has been developed and assessed in laboratory and field trials. The sensor is based on the molybdenum yellow method for phosphate detection in which a phosphate-containing sample is mixed with a reagent containing ammonium molybdate and ammonium metavanadate in an acidic medium. The yellow-colored compound which is formed absorbs strongly below 400nm and its absorbance is proportional to the concentration of phosphate in the original sample. The sensor utilizes a microfluidic manifold where mixing, reaction and detection take place. Optical detection is performed using a LED (light emitting diode) light source and a photodiode detector. The sensor also combines pumping system, power supply, reagent and waste storage, and wireless communications into a compact and portable device. Here we report the successful use of the sensor to monitor phosphate levels in an estuarine environment

Autonomous nutrient detection for water quality monitoring

The ever increasing demand for real time environmental monitoring is currently being driven by strong legislative and societal drivers. Low cost autonomous environmental monitoring systems are required to meet this demand as current monitoring solutions are insufficient. This poster presents an autonomous nutrient analyser platform for water quality monitoring. Results from a field trial of the nutrient analyser are reported along with current work to expand the range of water quality targets

Impact of antiretroviral therapy on adult HIV prevalence in a low-income rural setting in Uganda: a longitudinal population-based study.

OBJECTIVE: To estimate the contribution to HIV prevalence of lives saved due to the introduction of antiretroviral therapy (ART) in rural Uganda in 2004. DESIGN: Open population-based cohort study. METHODS: An open general population cohort with annual demographic and HIV serostatus data is used to estimate annual HIV prevalence, HIV incidence, and mortality from 2000 to 2010. We calculated standardized mortality rates among HIV-positive adults and the expected number of deaths in the cohort if ART had not been available during 2004-2010, based on the average mortality rate in the 4 years (2000-2003) before ART introduction. RESULTS: During 2004-2010, the estimated prevalence increased by 29% from 6.9% to 8.9%. HIV incidence was 5.6 cases per 1000 person-years in 2004, falling to 3.9 cases per 1000 person-years in 2006, and slightly rising to 5.1 in 2010. There was an increase of 182 in the number of HIV-positive participants during that period, cumulatively 228 lives were saved due to ART. Expected lives saved due to ART accounted for an increasing proportion of the estimated HIV prevalence from 4.0% in 2004 to 29.4% in 2010. CONCLUSIONS: Expected lives saved due to ART largely accounted for the increased estimated HIV prevalence from 2004 to 2010. Because HIV prevalence survey results are important for planning, programming, and policy, their interpretation requires consideration of the increasing impact of ART in decreasing mortality

Next generation autonomous chemical sensors for environmental monitoring

Microfluidic technology has great potential to fulfil the increasing demand for environmental monitoring. Through the minimisation of reagents, standard solutions and power consumption, compact autonomous instruments have been developed to perform in situ monitoring of remote locations over long deployable lifetimes. The objective of this research is to produce autonomous chemical sensing platforms with a price performance index that creates a significant impact on the existing market. The main focus is on developing a detection platform for ammonium, nitrate and nitrite for water and wastewater using colorimetric techniques. The goal is to integrate polymer actuators valves into the microfluidic chip, to drive down the overall cost

Enrollment and Disenrollment in Voluntary Prekindergarten: A Study of Educational Leaders’ Decision-Making

This qualitative case study focused on how school leaders’ understandings of (dis)ability were implicated in decision-making and affected student (dis)enrollment in Florida’s Voluntary Prekindergarten Program (VPK). More specifically it explored how leaders in private VPK programs invoked conceptions of normality, and subsequently abnormality, during decision-making processes for student (dis)enrollment. Combining a critical poststructuralist approach (critical disability studies, critical policy analysis), decision-making on (dis)enrollment was contextualized within the current policy ecology. This policy ecology was framed as an historical development of policies regarding preschool for children with and without disabilities in a marketplace shaped by the convergence of federal, state, and local policy, which tended to be based on deficit-oriented perspectives of disability that functioned to (re)constructed what was understood as (dis)ability. Further, findings focused on how policy, market, and VPK leaders’ understanding of (dis)ability influenced decision-making rationales and outcomes affecting (dis)enrolled students. Findings indicated their sense of identity impacted their interpretation of and reaction to program polices, local market pressures and their construction of the “good consumer”—a parent/child dyad prepared for rigor and the exhibition of self-control. Reciprocity emerged as a theme and suggested good consumers reinforced VPK leaders’ desired identity. In addition, VPK leaders’ justified enrollment and disenrollment decisions within a continuum of exchanges that occurred between consumers and themselves. Leaders who embraced service or spiritual based leadership practices tended to be more inclusive of children with diverse needs. Implications for future research should address 1) how VPK leaders include children with a range of abilities in their (pre)schools, 2) examine parents’ decision-making practices about their child’s (dis)enrollment in VPK centers, 3) policy clarification at the intersection of IDEA, ADA, and VPK, and 4) explore how local education agencies and private preschools can build infrastructure to support the inclusion of children with diverse learning needs in VPK centers. Such research can shed light on the complexity of decision-making with respect to enrollment for publicly-funded voucher programs on the private VPK market and how those decisions function to (re)shape discourses of normality in early childhood

Microfluidic chip development for an autonomous field deployable water quality analyser

This work presents the ongoing development of a microfluidic chip for a low cost field deployable phosphate analyser for water. The phosphate analyser is a fully integrated system incorporating fluid handling, microfluidic technology, colorimetric chemical detection, and real time wireless communications in a compact and rugged portable device

Distributed chemical sensor networks for environmental sensing

Society is increasingly accustomed to instant access to real-time information, due to the ubiquitous use of the internet and web-based access tools. Intelligent search engines enable huge data repositories to be searched, and highly relevant information returned in real time. These repositories increasingly include environmental information related to the environment, such as distributed air and water quality. However, while this information at present is typically historical, for example, through agency reports, there is increasing demand for real-time environmental data. In this paper, the issues involved in obtaining data from autonomous chemical sensors are discussed, and examples of current deployments presented. Strategies for achieving large-scale deployments are discussed

Autonomous nutrient detector for water and wastewater applications

An autonomous microfluidic sensor for phosphate in environmental waters has been developed and validated in laboratory and field trials. The sensor is based on the molybdenum yellow method for phosphate detection and employs a microfluidic manifold where mixing, reaction and detection take place. Optical detection is performed using a light emitting diode (LED) light source and a photodiode detector, while wireless communications allow near real-time access to the collected data. In parallel with this work, detection schemes for other nutrients (ammonia, nitrate/nitrite) are being developed, with the goal of developing a low cost, field deployable multi-nutrient detection platform. Utilising colorimetric chemistry and LED-based detection systems allows a modular approach which facilitates integration of new detection schemes with the platform provided by the phosphate sensor. The multi-nutrient analyser system will benefit a range of users including local authorities, monitoring agencies and the municipal and industrial wastewater treatment sectors