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Printed sensors for indoor air quality : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering, Massey University, Albany, New Zealand
(Massey University, 2022) Rehmani, Muhammad Asif Ali
On average, a human inhale about 14,000 litres of air every day. The quality of inhaled air is highly important as the presence of pathogens and contaminants in air can adversely affect human health. Generally, the probability of pathogens/contaminant is high in indoor environment where humans spend an estimated 90% of their total lifetime. Continuous urbanization, increasing population, technological advancement and automation has further increased the time spent indoors. The length of exposure and indoor activities such as cooking, smoking, ventilation and frequency of cleaning can further aggravate the health risk due to localized higher concentrations of the contaminants. According to the Environmental Protection Agency (EPA), poor indoor air quality (IAQ) is considered one of the top environmental dangers to the public as increasing number of people are suffering from asthma, allergies, heart disease, and even lung cancer. In New Zealand, poor air quality is estimated to cause 730 premature deaths and cost over one billion dollars in restricted activity days per year. The above premise cannot be validated until and unless there are means and measures of continually monitoring the indoor air pollutants with emphasis that the same can be fabricated using low cost and energy efficient methods. Furthermore, any remedial actions cannot be undertaken if the quantitative values of the environmental pollutants are unknown. Existing solutions for the air quality monitoring are expensive and can only be applied in certain numbers, leaving areas of the houses, offices, and schools unmonitored. Therefore, a ubiquitous system of air quality monitoring is needed, the one that can be applied on large areas like walls, roofs and so on. Such a prevalent system will allow sensing of air quality parameters rapidly, continuously, and with low power consumption. To realize the bigger objective of achieving sensing and aware surfaces for indoor air quality, this research proposes to print sensors on large surfaces rather than making them in batches and packaging in discrete units. Recent advancements in inkjet printing provide solutions which can enable the implementation of such sensors. However, the choice of inkjet printing method has major impact on the efficacy of printed sensors. Therefore, we have explored printing techniques based on conventional screen printing and non-conventional electrohydrodynamic (EHD) inkjet printing. These printing methods offer low-cost, rapid prototyping and high-thorough-put conductive printing of features as compared to other inkjet printing methods with the latter bringing further advantages of improved resolution, scalability, customization and little or no environmental waste printing solution. For screen printing, laser ablation process has been used to implement several customized transduction schemes. The utility of this technique is demonstrated by humidity sensing. It has been found that the designs of the transduction electrodes can easily be customized, and large area printing can be realized on the substrate. The fabricated humidity sensor provides higher sensitivity through bio-compatible sensing layer with good response and recovery time. Next, EHD printing was explored for high-resolution conductive printing on flexible substrates. Current EHD printing focuses on improving the print resolution by decreasing the printhead nozzle diameter thus limiting the type of ink to be used for printing purpose. In the proposed EHD printhead design we overcame this major shortcoming by improving the resolution of printed feature with a bigger nozzle of 0.5 mm diameter. This resulted in the printed feature resolution of less than 10 µm in general with the highest achieved resolution 1.85 µm. The effective nozzle diameter to printed feature ratio of more than 250 was achieved. The use of bigger nozzle for fine resolution printing opens the avenue for utilizing higher concentration of metallic nano-particles inks through EHD printing. The hallmark of the presented EHD printhead design is the utilization of off-the-shelf components which does not require expensive manufacturing process while highlighting the importance of wetting area profile of the nozzle to facilitate fine resolution printing which until now has not been explored in detail. Furthermore, the work highlights the issue of crack development during EHD printing in the conductive tracks while using available piezoelectric inkjet ink. Later the ink was modified to minimise the cracks in EHD printed features. Finally, a comprehensive study on the 3D printed microfluidic channels was conducted. The study highlights the variation of pressure developed in different microfluidic channel designs and the susceptibility of leakages from microfluidic devices. The work presents the possibility of utilizing the 3D printed microfluidics with printed sensors for deploying as lab-on-a-chip in various applications, such as passing a stream of air through sensors integrated in a microfluidic device for analysing the volatile organic compounds, humidity, toxic gases, and other analytes of interest. Overall, the presented work demonstrates the feasibility of using conventional and non-conventional printing methods through simple implementations for the fabrication of IAQ sensors with high degree of customization, low processing cost and scalability.
Spatial and environmental patterns of rare lotic macroinvertebrate diversity : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Manawatū, Palmerston North, New Zealand
(Massey University, 2021) Rados, Dimitrios A.
Stream macroinvertebrate communities comprise a few common taxa and many rare ones. Small populations of rare taxa can be more vulnerable to environmental change than those of common taxa. However, they are often discarded from community analyses on the grounds that they complicate data interpretation. The aim of this thesis was to evaluate the effect of rare taxa on assessing ecosystem health and on interpreting biodiversity patterns based on lotic macroinvertebrate communities. I assessed the effect of multiple types of rare taxa exclusion on biomonitoring, using macroinvertebrate data collected for the National River Water Quality Network of Aotearoa New Zealand. I compared the effect of different sampling methods on biodiversity patterns of rare taxa in pristine streams in the Tongariro National Park and determined the local environmental variables most strongly linked with common and rare taxa. Finally, I evaluated the effect dispersal processes and local environment have on structuring the common and rare components of lotic communities, considering the position within the stream network and the dispersal mode of the invertebrates. Exclusion of rare taxa led to significant misclassifications of ecological quality by biomonitoring tools that use presence-absence data, such as the Macroinvertebrate Community Index, and often masked their relationship with nutrient stressors. Different sampling methods collected clearly differentiated rare components of lotic assemblages, depending on the habitat sampled (riffles, non-riffles) and the life-stage of the invertebrates (benthic larvae, flying adults). A comprehensive species inventory can be compiled by combining methods, with benthic samples as the basis. Biodiversity metrics of the common and rare components of macroinvertebrate communities were related to similar environmental variables. While the structure of the two components was related to different variables, in combination they revealed a greater number of relationships with the environment. Rare taxa assemblages were not structured clearly by either local environment or dispersal processes, however their inclusion was necessary to demonstrate that the complete communities were determined by the local environment. Overall, I did not find any reason to exclude rare taxa from lotic macroinvertebrate studies, but rather found they can facilitate community analyses. Given the increasing threats on lotic macroinvertebrate biodiversity, it is also crucial to include them in such studies, hopefully so we can prevent their complete extinction.
Spiders as surrogate species in ecological monitoring, habitat classification and reserve selection : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Ecology at Massey University, Palmerston North, New Zealand
(Massey University, 2001) Coombe, Gil Michael Ian
The use of invertebrates in the monitoring of terrestrial ecosystems was investigated using spiders as a focal group. In a review of previous literature, spiders were found to meet the majority of criteria required of suitable ecological indicators, including high diversity and abundance, a widespread distribution, easy sampling and sorting, relatively low random fluctuation in population sizes and community composition, a range of dispersal abilities, measurable response to habitat change and representation of other taxa. The main weaknesses of spiders as ecological indicators were the lack of taxonomic expertise and sparse knowledge of baseline biology. However, these disadvantages could be rectified and it was concluded that spiders are suitable for further investigation as ecological indicators, involving field trials and hypothesis testing. The spider communities in the litter, herb and shrub layer of eight sites representing four habitat types within a forest successional series were sampled in Pouiatoa State Forest in Northern Taranaki. There were no distinct trends in spider richness or abundance across the successional series. However, spider species and family composition both reflected the successional stage from which they were taken. Site classifications using DCA and cluster analysis were similar when using either plant or spider data. Spider communities demonstrated potential for use in habitat classification of terrestrial ecosystems. Spiders and seven other ground-active invertebrate groups were sampled with pitfall traps from fourteen forest remnants within the Rangitikei Ecological Region to test whether spiders were able to act as indicators of plant and invertebrate diversity. Within-site richness (α-diversity) of spiders was strongly correlated with that of all other invertebrates combined, but spiders were not good predictors of between-site richness (²- diversity) of all other invertebrates. Correlation between the α- and β-diversities of plants and invertebrates were low, indicating that maximising plant diversity in reserve selection might not maximise invertebrate diversity. It is recommended that ground-active invertebrates be included in surveys of potential forest reserves. Spiders are a useful surrogate group for invertebrate communities and could be more widely used in the assessment, monitoring and management of terrestrial ecosystems.
Arsenic in urban air : sources, health risk and mitigation : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Environmental Health, Massey University, Wellington, New Zealand
(Massey University, 2015) Mitchell, Tamsin A.
Over recent years, several studies have suggested that high concentrations of arsenic may occur in outdoor air in urban areas of New Zealand on some winter nights. These spikes in arsenic concentrations are presumed to be caused by some householders burning copper-chrome-arsenate (CCA)-treated wood as a fuel for domestic home heating, but detailed examination of the issue has been lacking. The aims of this work are to examine the concentrations and source(s) of arsenic in ambient air in a representative New Zealand wood-burning community, identify and quantify potential health risks linked to both arsenic in air and the activity of burning CCA-treated wood, and undertake an initial exploration of social factors that may contribute to the issue. The town of Wainuiomata in the Wellington region was selected as the representative community. Concentrations of total arsenic in Wainuiomata outdoor air were measured over two years, along with a number of other relevant variables useful for source characterisation, including two size fractions of particulate matter (PM10 and PM2.5), black carbon and other trace elements. Over both years, concentrations of arsenic in Wainuiomata air were indistinguishable from the national ambient air quality guideline of 5.5 ng/m3 expressed as an annual average. Arsenic levels were strongly seasonal and peaked during the winter months, but with significant variability from night to night. The highest 24-hour concentration recorded during winter was 79 ng/m3. Results of correlation analysis and source attribution provide strong support for the idea that the principal source of elevated arsenic in outdoor air is the domestic burning of wood treated with CCA preservative. A detailed exposure model was developed and applied to estimate and contextualise potential arsenic exposures that may be experienced by adults and children living in the community, and quantify relative health risks. Potential community health impacts are estimated not to be significant where exposure is limited to outdoor arsenic, including that which infiltrates into the indoor environment, where “not significant” is defined as an additional lifetime cancer risk of less than 1 in 100,000 and a hazard quotient less than 1. Annual average arsenic in outdoor air would need to be around 15 times higher than the guideline value to increase an individual’s attributable lifetime cancer risk to 1 in 10,000. Of more potential concern are health risks arising from indoor exposure for residents who use CCA-treated timber as supplementary firewood where this may lead to fugitive emissions of arsenic from the firebox into indoor air. Not only does the predicted excess lifetime cancer risk approach 7 in 100,000, but there are also non-cancer health risks to children due to short-term exposure to the relatively higher levels of arsenic during the winter months. Hazard quotients above 1 were found to potentially exist for a small number of children (4%) based on the likelihood of living in a home where CCA-treated timber might be burnt combined with the presence of at least one adult smoker. However, overall greatest potential for acute health risk for children was found to be posed by accidental or incidental ingestion of CCA-wood ash, which contains very high concentrations of arsenic. Results of focus group sessions and community surveying provided useful contextual information about the source activity and identification of some potentially modifiable social factors, along with some understanding about why prohibition of the activity of burning CCA-treated wood may be ineffective. Findings included an upper estimate of the proportion of households that may burn CCA-treated timber (approximately 16%), and identification of the problem that most residents are not able to distinguish treated from untreated wood. A number of recommendations are made. Despite the preliminary nature of the findings due to uncertainties in the modelling and toxicity reference values, it is recommended that efforts should be made to discourage the practice of CCA-wood burning as a precautionary measure to protect against inhalation exposure to indoor sources of arsenic and ingestion of contaminated ash by children. Community education initiatives would need to be developed from the perspective of local residents, most of whom cannot identify CCA-treated wood. It would be ideal if this were complemented with a high-level review of the policy and regulatory framework which permits the manufacture, use and disposal of CCA-treated wood in New Zealand, to determine where risks might be best managed.
The development of the Waterway self assessment form, a stream management tool for landowners : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Ecology at Massey University
(Massey University, 2000) Polglase, Miranda Anne
Increasing environmental awareness amongst the general public and more specific user groups, such as land owners, has led to concern about the impacts of land use on specific environmental qualities such as water quality and stream biota. As a result, methods for reducing and or ameliorating these impacts have become a key area of research in freshwater ecology over the last decade (Fahey and Rowe, 1992; Hanchet, 1989; Hughes, et al., 1986; Osborne and Wiley, 1988; Quinn, et al., 1997; Watson, 1986; Wilcock, 1986; Winterbourn, 1986). The dominant focus of this research has been in riparian management (Large and Petts, 1992; Platts, et al., 1987; Quinn, et al., 1993). As many streams and rivers in New Zealand flow at some stage through pastoral land, the responsibility of managing riparian zones is largely that of the landowners. Simple tools for managing waterways and their riparian zones, which take into account the requirements of individual landowners, and also facilitate education and awareness, are now needed (Quinn and Collier, in press).
Tune in share out : this thesis is presented in partial fulfilment of the requirements for the degree of Master of Design at Massey University, Wellington, New Zealand
(Massey University, 2010) Mitchell, Greer
This thesis explores the intersections of ubiquitous technologies, embedded democracies, and bright green futures and how that is resolved in a user interface design for a citizen centric mobile phone application. My main question of enquiry is: How can I connect citizens to their local environment through human interface design on a mobile platform? The Politics of Nature by Bruno Latour proposes; ‘An end to the old dichotomy between nature and society... of a collective, a community incorporating humans and non humans and building on the experiences of the sciences as they are actually practiced.’ (Latour, 2004, p. 186-206). Design research throughout this thesis explores the intersections of urban health, human interface design, captology, mobile and sensor technology and citizen science while proposing an interactive mobile application for local and national governments to engage with an increasingly urban and technological savvy agora. The aim of the accompanying mobile application prototype titled Tune In, Share Out (TISO), gives access to air and water quality information coupled with a mobile air quality sensor device which enables urban citizens to directly participate in the concept of the quantified self (Fawkes, 2010) by monitoring their pollution paths, while sharing this information through their respective social networks within a mobile mapping platform. Concurrently this project contributes air quality information to aid citizens, scientists and city planners to make more informed and sustainable decisions within their local environment and agora. Benefits of this application include citizen and environmental interaction and awareness, the ability for local government and citizens to enhance their tacit and embodied knowledge of respective groups and individual’s, enabling greater understanding of each others perspective, while offering a channel of participation to an otherwise silent segment of society.
Planar electromagmentic sensors for environmental monitoring : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Electricical Engineering at Massey University, Palmerston North, New Zealand
(Massey University, 2011) Yunus, Mohd Amri bin Md
Water is the essence of life and an important nutrient for every living thing. Therefore, ninety six novel planar electromagnetic sensors based on the combination of meander sensor and interdigital sensor have been designed, fabricated, and tested for the application of water quality monitoring. Experiments were conducted to obtain the impedance characterization for each sensor, and the results were used to estimate the important parameters that influence the performance of the sensors based on the equivalent electrical circuits. The best sensors were selected based on the design with the highest electrical parameters (total effective capacitance and effective inductance). Intensive modelling and simulation of the selected best sensors are also discussed where the results were compared with the simulation results. Furthermore, the best sensors have been tested to detect nitrates contamination in distilled water using sodium nitrate (NaNO3) and ammonium nitrate (NH4NO3) solutions with different concentrations. The sensor that consists of the series combinations of spiral meander planar sensor (with five turns) with the interdigital sensor (with large negative electrode): SECS22_1 is the best sensor to detect the presence of nitrate added into distilled water and can estimate the concentration level. Furthermore, the sensor was tested with various kinds of prepared samples and natural water samples taken from natural sources around New Zealand. The outcomes have shown a very good correlation of contamination level, translated from the qualitative and quantitative results. Using the SECS22_1 sensor, a method to estimate nitrate contamination in natural water sources using Independent Component Analysis (ICA) has been explained and demonstrated. This model can accurately estimate nitrate in a natural water source as shown by the results. A low-cost system has been developed based on SECS22_1, a microcontroller, a waveform circuit, signal conditioning circuits, and LabView. The results from the experiment have shown the low-cost system has the potential to be used as a tool for nitrate detection and water sources quality monitoring in remote places such as farms. Finally, the work and improvement for future consideration are also discussed in this research.
Conservation issues for Hochstetter's frog (Leiopelma hochstetteri): monitoring techniques and chytridiomycosis prevalence in the Auckland region, New Zealand : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Auckland, New Zealand
(Massey University, 2009) Puig, Virginia Moreno
Amphibians are suffering extinctions and range contractions globally. This is caused by numerous factors and most of them are related to human activities. The overall aim of this thesis was to make a significant contribution to the conservation of the endemic amphibian Leiopelma hochstetteri through research. This was achieved by focusing in two of the main conservation issues for this species, the need for standardised and robust monitoring techniques to detect trends and changes in populations, and the determination of the prevalence of chytridiomycosis, caused by the amphibian chytrid fungus (Batrachochytrium dendrobatidis). Two populations of the Auckland Region were selected for this study, one on the mainland (Waitakere Ranges) and the only known offshore island population of this species (Great Barrier Island). For both study sites different monitoring methods were used to obtain some population parameters. Site occupancy models of MacKenzie et al. (2002) gave reliable site-specific estimations of occupancy and detection probability using covariate information and presence-absence data collected from 50 sites in the Waitakere Ranges and four repeated visits during 2008. Elevation and distance searched were found to have an important effect on occupancy levels, while time taken to search the site was important variable determining detection probabilities. Also, parameters were estimated for three age classes separately. Statistical models were used to infer abundance from occupancy analysis, and results were compared with the distribution of relative abundances obtained from repeated transect counts and an established sight/re-sight criterion. In addition, the use of surrogate measures for relative abundance was explored. Detection probability and the distance to first frog found were found to have a significant correlation with relative abundance. These measures can be used to infer relative abundance in future site occupancy surveys. Two surveys and a pilot site occupancy survey were conducted on Great Barrier Island, and presence of frogs was confirmed atthe northern block, and in a small seepage in the central block. No new locations were found. Waitakere Ranges and Great Barrier Is. populations were tested for the presence of chytridiomycosis, and all frogs sampled tested negative (n = 124) which means that if present chytridiomycosis prevalence is lower than 5% with a 95% confidence interval. This and previous evidence suggests that L. hochstetteri may be resistant or immune to the disease. However, to confirm this additional studies are needed.

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