Sustainability in design: now! Challenges and opportunities for design research, education and practice in the XXI century

Copyright @ 2010 Greenleaf PublicationsLeNS project funded by the Asia Link Programme, EuropeAid, European Commission

Development of Microwave/Droplet-Microfluidics Integrated Heating and Sensing Platforms for Biomedical and Pharmaceutical Lab-on-a-Chip Applications

Interest in Lab-on-a-chip and droplet-based microfluidics has grown recently because of their promise to facilitate a broad range of scientific research and biological/chemical processes such as cell analysis, DNA hybridization, drug screening and diagnostics. Major advantages of droplet-based microfluidics versus traditional bioassays include its capability to provide highly monodispersed, well-isolated environment for reactions with magnitude higher throughput (i.e. kHz) than traditional high throughput systems, as well as its low reagent consumption and elimination of cross contamination. Major functions required for deploying droplet microfluidics include droplet generation, merging, sorting, splitting, trapping, sensing, heating and storing, among which sensing and heating of individual droplets remain great challenges and demand for new technology. This thesis focuses on developing novel microwave technology that can be integrated with droplet-based microfluidic platforms to address these challenges. This thesis is structured to consider both fundamentals and applications of microwave sensing and heating of individual droplets very broadly. It starts with developing a label-free, sensitive, inexpensive and portable microwave system that can be integrated with microfluidic platforms for detection and content sensing of individual droplets for high-throughput applications. This is, indeed, important since most droplet-based microfluidic studies rely on optical imaging, which usually requires expensive and bulky systems, the use of fluorescent dyes and exhaustive post-imaging analysis. Although electrical detection systems can be made inexpensive, label-free and portable, most of them usually work at low frequencies, which limits their applications to fast moving droplets. The developed microwave circuitry is inexpensive due to the use of off-the-shelf components, and is compact and capable of detecting droplet presence at kHz rates and droplet content sensing of biological materials such as penicillin antibiotic, fetal bovine serum solutions and variations in a drug compound concentration (e.g., for Alzheimer’s Disease). Subsequently, a numerical model is developed based on which parametrical analysis is performed in order to understand better the sensing and heating performance of the integrated platform. Specifically, the microwave resonator structure, which operates at GHz frequency affecting sensing performance significantly, and the dielectric properties of the microfluidic chip components that highly influence the internal electromagnetic field and energy dissipation, are studied systematically for their effects on sensing and heating efficiency. The results provide important findings and understanding on the integrated device operation and optimization strategies. Next, driven by the need for on-demand, rapid mixing inside droplets in many applications such as biochemical assays and material synthesis, a microwave-based microfluidic mixer is developed. Rapid mixing in droplets can be achieved within each half of the droplet, but not the entire droplet. Cross-center mixing is still dominated by diffusion. In this project, the microwave mixer, which works essentially as a resonator, accumulates an intensive, nonuniform electromagnetic field into a spiral capacitive gap (around 200 μm) over which a microchannel is aligned. As droplets pass by the gap region, they receive spatially non-uniform energy and thus have non-uniform temperature distribution, which induces non-uniform Marangoni stresses on the interface and thus three-dimensional (3D) chaotic motion inside the droplet. The 3D chaotic motion inside the droplet enables fast mixing within the entire droplet. The mixing efficiency is evaluated by varying the applied power, droplet length and fluid viscosity. In spite of various existing thermometry methods for microfluidic applications, it remains challenging to measure the temperature of individual fast moving droplets because they do not allow sufficient exposure time demanded by both fluorescence based techniques and resistance temperature detectors. A microwave thermometry method is thus developed here, which relies on correlating fluid temperature with the resonance frequency and the reflection coefficient of the microwave sensor, based on the fact that liquid permittivity is a function of temperature. It is demonstrated that the sensor can detect the temperature of individual droplets with ±1.2 °C accuracy. At the final part of the thesis, I extend my platform technology further to applications such as disease diagnosis and drug delivery. First, I develop a microfluidic chip for controlled synthesis of poly (acrylamide-co-sodium acrylate) copolymer hydrogel microparticles whose structure varies with temperature, chemical composition and pH values. This project investigates the effects of monomer compositions and cross-linker concentrations on the swelling ratio. The results are validated through the Fourier transform infrared spectra (FTIR), SEM and swelling test. Second, a preliminary study on DNA hybridization detection through microwave sensors for disease diagnosis is conducted. Gold sensors and biological protocols of DNA hybridization event are explored. The event of DNA hybridization with the immobilized thiol-modified ss-DNA oligos and complimentary DNA (c-DNA) are monitored. The results are promising, and suggests that microwave integrated Lab-on-a-chip platforms can perform disease diagnosis studies

1995 BRAC Commission

Base Closure Cleanup Seminar December 1993. File 2 of 4. Box 72, IA-008

1995 BRAC Commission

Base Closure Cleanup Seminar December 1993. File 1 of 4. Box 72, IA-008

The impact of workplace physical activity interventions on university employees health, wellbeing and behaviour change

The benefits of participating in regular physical activity are wide-ranging and well-accepted globally, yet physical inactivity is increasing, especially amongst adults. Occupations involving sedentary behaviour are considered a leading contributor to the inactive lifestyle responsible for many health-related problems. An increasing number of occupations involving predominantly sedentary work and the incidence of work-related health issues is becoming more prevalent, with evidence suggesting that adults spend approximately 60% of their waking time at work. Moreover, higher educational institutions are arguably one of the predominant sources of influence on society and can play a significant role in developing the nation and changing attitudes. Despite this, research in physical activity, sedentary behaviour, health and wellbeing substantially lacks in these settings. Therefore, this thesis adds to the limited knowledge about physical activity, sedentary behaviour, health and wellbeing interventions on university employees in the workplace. To elucidate this, several studies were conducted to evaluate existing physical activity levels and sedentary behaviour, followed by the exploration of barriers to physical activity amongst employees. The outcomes of these investigations contributed to the subsequent design and implementation of five physical activity, health and wellbeing interventions within the university. The five interventions were: • Accessibility and the availability of exercise resources in the workplace • Reducing sitting time through sit and stand workstation amongst university employees • Exploring the impact of seated, standing and walking meetings in the university setting • Getting university employees on the stairs: The impact of points of decision prompts • Promoting PA amongst employees through the 10,000 steps team-based competition Findings concluded that there is potential for physical activity, sedentary behaviour, health, and wellbeing interventions to be extended to other settings to promote physical activity engagement, reduce sitting time, and improve employees health and wellbeing. For instance, findings of intervention one indicate, employees engaged in 1287 minutes of physical activity/exercise throughout the intervention period and staff reported positive mood, work productivity and stress relief by having access to the exercise resources in the workplace. The intervention two findings indicate that having access to the height-adjustable sit-stand workstation resulted in sedentary behaviour reducing from 1974 to 821 minutes. Standing time increased from 439 minutes to 923 minutes across the week. The results of intervention three demonstrated that staff indicated enhanced anger, fatigue, tension, and vigour post seated meeting instead of standing and walking meetings. The outcomes of this thesis demonstrate that these interventions can be generalizable and physical activity, sedentary behaviour, and health-related interventions must be tailored to the needs of employees in other settings. The intervention four results demonstrated that 84 participants noticed the banners, 54 were influenced to take the stairs, 68 felt physical, and 66 felt mental benefits of taking the stairs, whilst 88 suggested that the banners displayed in the workplace will influence them to take the stairs in future. Intervention five showed that the daily average steps increased from 5959 to 10308, and staff reported motivation, competitiveness, enjoyment, active and behaviour change due to 10,000 steps challenge intervention. These findings support the implementation of physical activity, sedentary behaviour, and health-related interventions across settings. This thesis contributes to the existing knowledge of behaviour theories, including the Trans-theoretical Model, Self-determination theory and Social-Ecological Model in the subject of exercise psychology associated with public health, physical activity, sedentary behaviour, health, and wellbeing of employees in the university workplace