Thesis (MEng) - Swinburne University of Technology, Industrial Research Institute Swinburne - 2007. / A thesis submitted for fulfillment of the requirement for the degree of Master of Engineering, Industrial Research Institute, Swinburne University of Technology - 2007. Typescript. Includes bibliographical references (p. 148-155).

Thesis (M.S.)--Michigan State University. Dept. of Electrical and Computer Engineering, 2006. / Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 51-52). Also issued in print.

Thesis (Ph.D.) - University of St Andrews, January 2007.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006. / Tolbert, Laren, Committee Member ; Perahia, Dorva, Committee Member ; Perry, Joseph, Committee Member ; Collard, David, Committee Member ; Bunz, Uwe, Committee Chair.

abstract: Within the last decade there has been remarkable interest in single-cell metabolic analysis as a key technology for understanding cellular heterogeneity, disease initiation, progression, and drug resistance. Technologies have been developed for oxygen consumption rate (OCR) measurements using various configurations of microfluidic devices. The technical challenges of current approaches include: (1) deposition of multiple sensors for multi-parameter metabolic measurements, e.g. oxygen, pH, etc.; (2) tedious and labor-intensive microwell array fabrication processes; (3) low yield of hermetic sealing between two rigid fused silica parts, even with a compliance layer of PDMS or Parylene-C. In this thesis, several improved microfabrication technologies are developed and demonstrated for analyzing multiple metabolic parameters from single cells, including (1) a modified "lid-on-top" configuration with a multiple sensor trapping (MST) lid which spatially confines multiple sensors to micro-pockets enclosed by lips for hermetic sealing of wells; (2) a multiple step photo-polymerization method for patterning three optical sensors (oxygen, pH and reference) on fused silica and on a polyethylene terephthalate (PET) surface; (3) a photo-polymerization method for patterning tri-color (oxygen, pH and reference) optical sensors on both fused silica and on the PET surface; (4) improved KMPR/SU-8 microfabrication protocols for fabricating microwell arrays that can withstand cell culture conditions. Implementation of these improved microfabrication methods should address the aforementioned challenges and provide a high throughput and multi-parameter single cell metabolic analysis platform. / Dissertation/Thesis / M.S. Electrical Engineering 2014

It has long been established that the physical properties of the cell’s surrounding microenvironment has the ability to impose its influence on a range of cell processes. Morphology, differentiation, and proliferation have all been shown to be sensitive to the mechanical cues inherent within the extracellular matrix. Although significant advancements in microfabrication and cell mechanics have been made, questions regarding how physical interactions guide biological systems in three dimensions remain unanswered. By utilizing cocultured systems and microfabricated channeled topographies, we reveal that the three dimensional nature of the environment is capable of driving cell patterning. Contact guidance is the phenomenon by which cells will orient themselves along the geometric patterns of a substrate. Much of its research has focused on the nano/micro scale of two dimensional topographies, affecting alignment along grooves. We have revealed that contact guidance has the ability to impose far more complex cellular behaviour in three dimensional systems. Furthermore, by modulating the elements of confinement surrounding cells, we directed the balance of binding forces between cells and substrate leading to significantly different cell type dependent morphologies. By then altering the geometry of the topography, we revealed the ability to induce cell type separation in cocultured systems. These concepts led to the subsequent discovery that confinement induces three dimensional spheroidal growth of embryonic stem cells. These results reveal that the element of confinement not only influences patterning in three dimensions but guides the fundamental early stages processes essential to all life.

Orientador: João Sinézio de Carvalho Campos / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-22T04:59:19Z (GMT). No. of bitstreams: 1 RicchiJunior_ReinaldoAlberto_D.pdf: 3389529 bytes, checksum: 30c41e1272f73cf9094e8b6aac68ea93 (MD5) Previous issue date: 2013 / Resumo: A versatilidade do polifluoreto de vinilideno (PVDF) abriu um grande número de possibilidades de pesquisa para este trabalho. Após uma completa revisão bibliográfica sobre as aplicações deste material, o transdutor ultrassônico de PVDF, acoplado a um reator e a um microreator do elastômero polidimetilsiloxano (PDMS), foi o sistema escolhido para esta tese. Tal sistema acelerou reações de Morita-Baylis-Hillman (MBH). O primeiro teste foi realizado em um reator "macroscópico" de PDMS para analisar o comportamento da reação MBH com este material. Em seguida, após o aprofundamento dos estudos, foi realizada uma reação MBH no interior do microreator, também de PDMS, e os resultados mostraram que o fenômeno de cavitação é significativamente maior neste caso, abrindo perspectivas para trabalhos futuros. Análises de espectroscopia de ressonância magnética nuclear (RMN) e de cromatografia gasosa (CG) comprovaram a eficácia do transdutor ultrassônico. Também foram fabricadas microestruturas de PVDF pela técnica de Litografia Macia por um novo processo, abrindo novas perspectivas de pesquisa / Abstract: The versatility of polyvinylidene fluoride (PVDF) has opened a lot of possibilities for this research work. After a literature review about the applications of this material, the PVDF ultrasonic transducer coupled to a reactor and a microreactor of the elastomer polydimethylsiloxane (PDMS) was the system chosen for this thesis. Such system has accelerated reactions Morita-Baylis-Hillman (MBH). The first test was conducted in a "macroscopic" PDMS reactor to analyze the behavior of the MBH reaction with this material. Then, after further studies, the MBH reaction was performed inside the microreactor, also of PDMS, and the results showed that the phenomenon of cavitation is significantly higher in this case, opening perspectives for future work. Analysis of nuclear magnetic resonance spectroscopy (NMR) and gas chromatography (GC) demonstrated the effectiveness of the ultrasonic transducer. PVDF microstructures were also fabricated by Soft Lithography by a new process, opening new perspectives of research / Doutorado / Ciencia e Tecnologia de Materiais / Doutor em Engenharia Química

Orientador: David Mendez Soares / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-31T18:01:06Z (GMT). No. of bitstreams: 1 Casagrande_PaulaSimoes_M.pdf: 7069712 bytes, checksum: cba42a97bc9e94ebc92b3ea0cc517e17 (MD5) Previous issue date: 2016 / Resumo: Neste trabalho foram desenvolvidos e caracterizados transistores de efeito de campo sensíveis a íons (Ion Sensitive Field Effect Transistor ¿ ISFET) com dois óxidos de porta distintos, óxido de silício (SiO2) e óxido de titânio sobre óxido de silício (TiO2/SiO2). Estes sensores foram fabricados utilizando tecnologia de micro fabricação de silício. A caracterização elétrica destes dispositivos foi realizada para MOSFETs de caracterização analisando-se as curvas de diodo, curvas de capacitância, a tensão de limiar e a transcondutância dos dispositivos fabricados. Para as amostras de SiO2 os valores típicos obtidos foram 6,4±0,1 pF para a capacitância máxima, 1,3±0,1 V para a tensão de limiar e 3,5±0,1 µS para a transcondutância, e para as amostras de TiO2/SiO2 foram 64±1 pF, -2,0±0,1 V e 10,5±0,1 µS, respectivamente. Os ISFETs foram testados em meios líquidos utilizando-se soluções tampão. Os ISFETs de SiO2 apresentaram pouca sensibilidade à variação de pH e os ISFETs de TiO2/SiO2 apresentaram baixa sensibilidade para pH baixo e maior sensibilidade para pH alto. Foi desenvolvido um sistema para medidas eletroquímicas utilizando os sensores em solução / Abstract: In this work were developed and characterized Ion Sensitive Field Effect Transistors (ISFET), with two different gate oxides: silicon oxide (SiO2) and titanium oxide on silicon dioxide (TiO2/SiO2). These sensors were manufactured using silicon micro fabrication technology. The electrical characterization of these devices has been done on MOSFETs, analyzing the diode curves, the capacitance curves, the threshold voltage and the transconductance of the manufactured devices. For the SiO2 sample typical values were 6.4 ± 0.1 pF for maximum capacitance, 1.3 ± 0.1 V for threshold voltage and 3.5 ± 0.1 uS for maximum transconductance and for the TiO2/SiO2 samples were 64 ± 1 pF, -2.0 ± 0.1 V and 10.5 ± 0.1 ?S, respectively. The ISFETs were tested in liquid using buffer solutions. The ISFETs with SiO2 showed small sensitivity to pH variation, and the ones of with TiO2/SiO2 showed low sensitivity to low pH and higher sensitivity to high pH. A system was developed for electrochemical measurements using the sensors in solution / Mestrado / Física / Mestra em Física / 132989/2014-0 / CNPQ

Microencapsulation of stem cells in hydrogel for use in therapeutic applications has been shown to improve cell retention at the site of injuries due to their mechanical and immunoprotective properties. These microscale droplets (cocoons) can be produced at high throughputs within microfluidic channels. Currently, the ability for cells to egress hydrogel cocoons is under investigation. This egress can correlate with therapeutic efficacy, and so promoting or inhibiting the egress of cells can be a vital component of viable treatments. Previously, a second hydrogel layer was shown to reduce egress, but issues involving cell proliferation were unchanged. We propose a microfluidic process to encapsulate cells in two layers of thermoresponsive hydrogels, in which the inner core melts at physiological temperatures to form hollow cocoons that allow cells free motion inside the immunoprotective shell. We hypothesize that the open volume would increase cell viability and proliferation, without increasing cell egress due to the uninterrupted hydrogel shell. In this project the encapsulation of NIH 3T3 cells in hollow agarose cocoons was achieved. 3T3 cells were first encapsulated in thermoreversible gelatin which were then re-encapsulated in agarose through the use of a flow-focusing microfluidic channel with on-chip mixing of two inlet flows to produce hollow cocoons. The production of these cocoons showed the potential of high throughput, monodisperse samples with future investment. Preliminary investigation in the behavior of the encapsulated cells showed that the cells maintain high viability over the course of 48 hours. There are early indications that the hollow nature of correctly formed cocoons can limit cell egress, and may allow for proliferation in the cocoon.

Investigates the mechanical and electronic properties of two-dimensional nanomaterials under strain, addressing gaps in the existing literature. The primary challenge with these materials is the inconsistent application of high strain rates and the absence of experimental data at low temperatures. To overcome these challenges, we develop Microelectromechanical Systems (MEMS)-based devices for characterizing 2D nanomaterials and semiconductor materials at low temperatures. Four MEMS-based devices are developed to facilitate this characterization. The first device is a unique MEMS testing platform with on-chip actuation, sensing, and feedback control systems, capable of applying controlled displacements to nanoscale specimens while minimizing temperature fluctuations. To achieve this, MEMS thermal actuators with an axial stiffness of 40253.6 N/m are used. Capacitive sensors and V-beam amplification mechanisms are designed for precise measurement. The second device, the cascaded MEMS device, employs horizontal and vertical V-shaped structures to measure stress-strain curves of 2D nanomaterials at low temperatures. The third device is a customized MEMS electrostatic actuator for bending tests on silicon material under low-temperature conditions. Finally, two MEMS rotational structures, including a novel C-shaped structure, are developed to amplify movement. The MEMS devices are fabricated using bulk micromachining and deep reactive-ion etching (DRIE) with silicon-on-insulator (SOI) wafers, incorporating underpass technology for electrical isolation within the MEMS-based testing platforms. To optimize DRIE etching parameters for creating underpass islands in SOI MEMS, a study was conducted considering a total of nine wafers, divided into two batches for fabrication process, and examining their behavior concerning the etching process. The devices are optically characterized at room temperature and tested in a vacuum environment and at low temperatures using scanning tunneling microscope (STM) tool.