On-Chip Detection of Gel Transition Temperature using a Novel Micro-Thermomechanical Method

We present a new thermomechanical method and a platform to measure the phase transition temperature at microscale. A thin film metal sensor on a membrane simultaneously measures both temperature and mechanical strain of the sample during heating and cooling cycles. This thermomechanical principle of operation is described in detail. Physical hydrogel samples are prepared as a disc-shaped gels (200 μm thick and 1 mm diameter) and placed between an on-chip heater and sensor devices. The sol-gel transition temperature of gelatin solution at various concentrations, used as a model physical hydrogel, shows less than 3% deviation from in-depth rheological results. The developed thermomechanical methodology is promising for precise characterization of phase transition temperature of thermogels at microscale

Localized Dielectric Loss Heating in Dielectrophoresis Devices

Temperature increases during dielectrophoresis (DEP) can affect the response of biological entities, and ignoring the effect can result in misleading analysis. The heating mechanism of a DEP device is typically considered to be the result of Joule heating and is overlooked without an appropriate analysis. Our experiment and analysis indicate that the heating mechanism is due to the dielectric loss (Debye relaxation). A temperature increase between interdigitated electrodes (IDEs) has been measured with an integrated micro temperature sensor between IDEs to be as high as 70 °C at 1.5 MHz with a 30 Vpp applied voltage to our ultra-low thermal mass DEP device. Analytical and numerical analysis of the power dissipation due to the dielectric loss are in good agreement with the experiment data

Testing of hydrogen sensor based on organic materials

Práce je zaměřena na problematiku bezpečnostních vodíkových senzorů. Základní principy a teorie vodíkových senzorů je rozebrána v první části práce. Je navržena metodologie testování organických vodíkových senzorů vyvinutých a vyrobených na Fakultě Chemické Vysokého Učení Technického v Brně. Nejslibnější organický material byl testován. V závěrečné části byl navržen teplotní regulátor pro použití s keramickou senzorovou platformou.This thesis is focused on topic of safety hydrogen sensors. Theory of hydrogen sensors and main sensor principles are discussed. Methodology for testing of organic hydrogen sensors developed and fabricated at the Faculty of Chemistry of Brno University of Technology is outlined. A set of tests is done for the most promising organic material. Also, temperature regulator for ceramic sensor platform is designed.

Experimental investigation of the energy performance of a novel Micro-encapsulated Phase Change Material (MPCM) slurry based PV/T system

© 2015 Elsevier Ltd. As a follow-on work of the authors' theoretical study, the paper presented an experimental investigation into the energy performance of a novel PV/T thermal and power system employing the Micro-encapsulated Phase Change Material (MPCM) slurry as the working fluid. A prototype PV/T module of 800mm×1600mm×50mm was designed and constructed based on the previous modelling recommendation. The performance of the PV/T module and associated thermal and power system were tested under various solar radiations, slurry Reynolds numbers and MPCM concentrations. It was found that (1) increasing solar radiation led to the increased PV/T module temperature, decreased solar thermal and electrical efficiencies and reduced slurry pressure drop; (2) increasing the slurry Reynolds number led to the increased solar thermal and electrical efficiencies, decreased module temperature, and increased pressure drop; and (3) increasing the MPCM concentration led to the reduced module temperature and increased pressure drop. The experimental results were used to examine the accuracy of the established computer model, giving a derivation scale ranging from 1.1% to 6.1% which is an acceptable error level for general engineering simulation. The recommended operational conditions of the PV/T system were (1) MPCM slurry weight concentration of 10%, (2) slurry Reynolds number of 3000, and (3) solar radiation of 500-700W/m 2 ; at which the system could achieve the net overall solar efficiencies of 80.8-83.9%. To summarise, the MPCM slurry based PV/T thermal and power system is superior to conventional air-sourced heat pump systems (ASHP) and solar assisted heat pump systems (ISAHP), and has the potential to help reduce fossil fuel consumption and carbon emission to the environment

Thermal Microfluidic Devices; Design, Fabrication and Applications

This thesis investigates the thermal actuation and temperature measurement methods in microfluidic devices. We designed and fabricated microfluidic devices with various functionalities such as: bio sensing, particle counting, microscale calorimetry, and cellular temperature measurement. All of these functionalities use thermal measurement methods. When quantitative measurements are required, the label-free nature of thermal measurement methods, along with its simple readout, make it a powerful candidate for lab on a chip and bio sensing/detection applications. In this work, thermal measurement methods are used to characterize bio-samples, measure concentrations, study thermal responses, and even perform particle cytometry. However, thermal measurement methods are known for their low speed and low sensitivity characteristics, which are influenced by thermal properties of materials and structural design. On the microscale, we designed and fabricated microfluidic structures with modified thermal properties to achieve low response times and high sensitivity. To optimize our devices, we analyzed the thermal responses of the designed structures using a first order equivalent electrical circuit model. We then compared the results of the model to the fabricated device responses. To increase the functionality of our device, we used a number of temperature measurement techniques; thermal wave analysis, AC calorimetry, time of flight measurement, and the continuous recording of differential temperature. In this work, we fabricated an on-chip calorimeter with a 200 nL chamber volume and measured specific heat and thermal conductivity of water and glycerol. Also, we measured the thermal properties of the ionic liquids with the calorimeter. Moreover, we fabricated a calorimetric microfluidic biosensor to detect and measure the glucose levels of blood with concentrations of 0.05 to 0.3% wt/vol. We applied the same method to measure DNA concentration in buffer solution and a protein binding reaction. Also, we developed a method to count the number of particles passing through a micro channel while simultaneously measuring the size deference between particles by measuring changes in thermal conductivity. We fabricated a microfluidic platform to capture a single cell to measure the temperature of the cell in response to an external stimulation

Preliminary study on decision making factors to replace medical equipment in hospital

Maintaining medical equipment in hospital is a cost-deprived process yet is a crucial process that needs to be looked into. Maintaining is an ongoing process that starts with installation and ended up with disposed. The cost for maintaining equipment is often held a large portion in life cycle costing and huge amount of money need to be allocated to complete this process. The cost invested on maintaining the medical equipment should be worth the value without comprising the safety requirement and regulations. However, there are circumstances where hospitals are unable to decide when to dispose the equipment especially when the equipment reach the end of its life, incur high repairing cost, aging, and frequent failed to function. Management of hospital come into dead end solution as there are lack of proper guidelines on maintaining medical equipment and therefore the equipment may be over maintained or under maintained. This paper provides a review of 100 papers from credible sources on maintaining activities of equipment to identify factors that are important for decision making to replace the medical equipment