<p>Cancer comprises a collection of diseases, all of which begin with abnormal tissue growth from various stimuli, including (but not limited to): heredity, genetic mutation, exposure to harmful substances, radiation as well as poor dieting and lack of exercise. The early detection of cancer is vital to providing life-saving, therapeutic intervention. However, current methods for detection (e.g., tissue biopsy, endoscopy and medical imaging) often suffer from low patient compliance and an elevated risk of complications in elderly patients. As such, many are looking to “liquid biopsies” for clues into presence and status of cancer due to its minimal invasiveness and ability to provide rich information about the native tumor. In such liquid biopsies, peripheral blood is drawn from patients and is screened for key biomarkers, chiefly circulating tumor cells (CTCs). Capturing, enumerating and analyzing the genetic and metabolomic characteristics of these CTCs may hold the key for guiding doctors to better understand the source of cancer at an earlier stage for more efficacious disease management.</p><p> The isolation of CTCs from whole blood, however, remains a significant challenge due to their (i) low abundance, (ii) lack of a universal surface marker and (iii) epithelial-mesenchymal transition that down-regulates common surface markers (e.g., EpCAM), reducing their likelihood of detection via positive selection assays. These factors potentiate the need for an improved cell isolation strategy that can collect CTCs via both positive and negative selection modalities as to avoid the reliance on a single marker, or set of markers, for more accurate enumeration and diagnosis.</p><p> The technologies proposed herein offer a unique set of strategies to focus, sort and template cells in three independent microfluidic modules. The first module exploits ultrasonic standing waves and a class of elastomeric particles for the rapid and discriminate sequestration of cells. This type of cell handling holds promise not only in sorting, but also in the isolation of soluble markers from biofluids. The second module contains components to focus (i.e., arrange) cells via forces from acoustic standing waves and separate cells in a high throughput fashion via free-flow magnetophoresis. The third module uses a printed array of micromagnets to capture magnetically labeled cells into well-defined compartments, enabling on-chip staining and single cell analysis. These technologies can operate in standalone formats, or can be adapted to operate with established analytical technologies, such as flow cytometry. A key advantage of these innovations is their ability to process erythrocyte-lysed blood in a rapid (and thus high throughput) fashion. They can process fluids at a variety of concentrations and flow rates, target cells with various immunophenotypes and sort cells via positive (and potentially negative) selection. These technologies are chip-based, fabricated using standard clean room equipment, towards a disposable clinical tool. With further optimization in design and performance, these technologies might aid in the early detection, and potentially treatment, of cancer and various other physical ailments.</p> / Dissertation

Microfluidics is a field of research that enables the manipulation of fluids in the submillimetre length scale. The technology allows the development of lab-on-a-chip devices, which are miniaturized systems for chemical and biological analysis. Currently, the conventional manufacturing methods for these systems require multiple time-consuming steps. Therefore, focus has shifted towards laser micromachining as an alternative method. Direct laser writing would circumvent many of the steps required for the conventional methods, drastically reducing the process time. In this Master thesis project, it was shown that microfluidic chips can be manufactured using a Nd:YVO4 (532 nm) nanosecond laser system. The process was optimized for silicon and borosilicate glass substrates. Acoustic focusing of polystyrene beads was demonstrated for a system etched in silicon. The optimized process used a power of 50%, a frequency of 10 kHz, a scan speed of 60 mm/s with triple lines as fill type and it had an etch rate of 4.3 μm/pass. Processed wafers were cleaned in buffered HF and bonded using anodic bonding as well as adhesive bonding. Processing of glass proved unpredictable, resulting in cracks and chippings. However, in- and outlets were successfully etched through thin glass wafers. It was found that crucial factors for the process were to control the focus, positioning of structures, structure orientation and the pulse separation for a uniform distribution of pulses. Based on the results, it is estimated that the manufacturing process could be done in two to three days using the laser micromachining process.

This master’s thesis explores the possibility of calculating and using the pressure andvelocity fields responsible for acoustophoresis. The goal was to use simulated data,similar to two-dimensional particle tracks from a specific microfluidic platform, toestimate the force potential and solve the partial differential equation (PDE) thatgoverns the relationship between the force potential and the acoustic fields. Lastly,the possibility of identifying the mechanical properties of unknown particles, once theacoustic field was known, was investigated. The thesis found that solving the PDE usingthe finite difference method was likely not possible and an alternative method has beensuggested. It also found that the use of particle tracks to measure the compressibilityand density of cells as a biomarker is promising, as most simulated particles wereaccurately measured. / Denna uppsats utforskar möjligheten att bestämma och använda de tryck- och hastighetsfält som är ansvariga för akustofores. Målet var att använda simulerad data, likt två-dimensionella partikelbanor för en specifik mikrofluidisk plattform, för att uppskatta kraftpotentialen och lösa den partiella differentialekvation (PDE) som styr relationen mellan kraften och de akustiska fälten. Möjligheten att bestämma mekaniska egenskaper hos okända partiklar, när det akustiska fältet är känt, utreddes också. Slutsatsen är att det inte var möjligt att lösa PDEn med hjälp av finita differensmetoden och istället föreslås en alternativ metod. Preliminära simulerade tester att karaktärisera okända partiklar gav positiva resultat, givet att de akustiska fälten är kända i två dimensioner.

During the last decade, ultrasonic manipulation has matured into an important tool with a wide range of applications, from fundamental cell biological research to clinical and industrial implementations. The contactless nature of ultrasound makes it possible to manipulate living cells in a gentle way, e.g., for positioning, sorting, and aggregation. However, when manipulating cells using ultrasound, especially using high acoustic amplitudes, a great deal of heat can be generated. This constitutes a challenge, since the viability of cells is dependent on a stable physiological temperature around 37°C.      In this Thesis we present applications of ultrasonic manipulation of fluids, particles, and cells in temperature-controlled micrometer-sized devices fabricated using well established etching techniques, directly compatible with high-resolution fluorescence microscopy. Furthermore, we present ultrasonic manipulation in larger up to centimeter-sized devices optimized for fluid mixing and cell lysis. In the present work, two new ultrasonic manipulation platforms have been developed implementing temperature control. These platforms are much improved with increased performance and usability compared to previous platforms. Also, two new ultrasonic platforms utilizing low-frequency ultrasound for solubilization and cell lysis of microliter-volumed and milliliter-volumed samples have been designed and implemented.      We have applied ultrasound to synchronize the interaction between large numbers of immune, natural killer cells, and cancer cells to study the cytotoxic response, on a single cell level. A heterogeneity was found among the natural killer cell population, i.e., some cells displayed high cytotoxic response while others were dormant. Furthermore, we have used temperature-controlled ultrasound to form up to 100, in parallel, solid cancer HepG2 tumors in a glass-silicon multi-well microplate. Next, we investigated the immune cells cytotoxic response against the solid tumors. We found a correlation between the number of immune cells compared to the size of the tumor and the cytotoxic outcome, i.e., if the tumor could be defeated.             Finally, the effect of high acoustic pressure amplitudes in the MPa-range on cell viability has been studied in a newly developed platform optimized for long-term stable temperature control, independent on the applied ultrasound power. Lastly, we present two applications of ultrasonic fluid mixing and lysis of cells. One platform is optimized for small microliter-sized volumes in plastic disposable chips and another is optimized for large milliliter-sized volumes in plastic test tubes. The latter platform has been implemented for clinical sputum sample solubilization and cell lysis for genomic DNA extraction for subsequent pathogen detection / Ultraljudsmanipulering har under de senaste tio åren mognat och utvecklats till ett verktyg med ett brett användningsområde. Idag kan man finna applikationer inom allt från cellbiologisk grundforskning till industri samt sjukvård. Ultraljudsmanipuleringens kontaktlösa natur gör det till en varsam metod för att manipulera celler, till exempel inom positionering, sortering och aggregering. När ultraljud med hög amplitud används kan värmeutvecklingen, som är oundviklig, bli ett problem. För att kunna säkerställa hög cellviabilitet krävs temperaturkontroll som kan hålla en fysiologisk, stabil temperatur på 37°C.      I denna avhandling presenterar vi tillämpningar av temperaturkontrollerad ultraljudsmanipulering i mikrometerstora anordningar fabricerade med väletablerade etsningstekniker.  Dessa anordningar är optimerade för att vara fullt kompatibla med högupplöst fluorescensmikroskopi.  Vi demonstrerar även ultraljudsmanipulering i centimeterstora anordningar optimerade för omrörning och blandning av vätskor samt lysering av celler. Två nya plattformar för ultraljudsmanipulering med inbyggd temperaturkontroll har utvecklats. Dessa två plattformar erbjuder ökad prestanda, flexibilitet samt även användarvänlighet. Utöver dessa plattformar har ytterligare två anordningar för lågfrekvent ultraljudssolubilisering och cellysering av mikroliter- och milliliterstora prover konstruerats.      I denna avhandling har vi tillämpat ultraljud för att synkronisera interaktionen mellan populationer utav immunceller (natural killer-celler) och cancerceller för att på cellnivå studera det cytotoxiska gensvaret. Vi fann en heterogenitet hos immuncellspopulationen. Det manifesterade sig i en fördelning av immuncellerna, från celler med stort cytotoxiskt gensvar till inaktiva immunceller. Vi har dessutom använt temperaturkontrollerad ultrasljudsmanipulering för att skapa solida cancertumörer utav HepG2-cancerceller, upp till 100 stycken parallellt, i en multihåls-mikrotiterplatta bestående av glas och kisel. Med hjälp av dessa tumörer har vi studerat det cytotoxiska gensvaret från immuncellerna. Vi fann att förhållandet mellan antalet immunceller och storleken på tumören bestämde utfallet, det vill säga om tumören kunde bekämpas.      Vi presenterar dessutom effekten utav högamplitudsultraljudsexponering av cancerceller i en plattform speciellt designad för höga tryckamplituder med implementerad ultraljudseffektsoberoende temperaturkontroll. Slutligen presenterar vi två tillämpningar av ultraljud för vätskeblandning och cellysering. Den första tillämpningen är anpassad för små volymer i plastchip för engångsbruk och den andra är optimerad för större volymer i plastprovrör. Den senare tillämpningen är speciellt framtagen för ultraljudssolubilisering och cellysering utav kliniska sputumprover för att möjliggöra DNA-extrahering för detektion av smittämnen. / <p>QC 20150522</p>