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- Akhtar, Ahmad Saleem
(författare)
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Centrifugal microfluidics-based point of care diagnostics at resource limited settings
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advancements in medical diagnostics have allowed us to understand the underlying mechanism and treat the root cause for many diseases which had been causing morbidity and mortality up until this point in human history. Furthermore, many of the standard diagnostic procedures have now been transformed to provide answers at or near the point-of-care. However, the effects of these positive developments have not trickled down to the parts of our society which are considered underdeveloped and lack the necessary infrastructure and facilities. Diagnostics in such resource limited settings still lag behind and fail to provide the requisite healthcare. In order to translate the diagnostic solutions designed for central laboratories to resource limited settings, there are certain challenges that need to be addressed, such as portability, reduction in cost and ease-of-use, while keeping the sensitivity and specificity at the required level. The work presented in this thesis focuses on addressing some of these issues by using microfluidics to develop diagnostic platforms that are suitable to be used in resource limited settings. In paper I, a very low-cost and simple centrifugal microfluidic platform was developed to be used in settings which do not have a reliable supply of electricity. The platform uses a smartphone as a source of power and the sensors of the phone for speed control.In paper II, a portable and low-cost diagnostic platform was developed for multiplexed detection of biomarkers based on centrifugal microfluidics. The platform uses colorimetric detection and a simple readout method which does not require a spectrophotometer for quantification.In paper III, a platform was developed for COVID-19 diagnostics which combines centrifugal microfluidics with a novel bead-based strategy for signal enhancement. The platform uses fluorescent detection with a smartphone readout and has the capability to process up to 20 samples at the same time.In paper IV, as a follow up of paper III, a more advanced platform was developed for COVID-19 diagnostics which allows the operator to carry out nucleic acid amplification in a completely automated manner, from adding the sample to getting the final result.In paper V, an alternative method for detection of SARS-CoV-2 was developed using electrochemical biosensing. This work combines the electrochemical technique with a flexible printed circuit board for a rapid, amplification-free and label-free detection of target SARS-CoV-2 sequences.
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| 2. |
- Iseri, Emre
(författare)
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Microfluidic Compartmentalization for Smart Materials, Medical Diagnostics and Cell Therapy
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The organisation of fluids in small compartments is ubiquitous in nature, such as in the cellular composition of all life. This work explores several engineering avenues where microscale fluid compartmentalization can bring novel material properties or novel functionality in life sciences or medicine. Here, we introduce four unique compartmentalization methods: 1) 3D fluid self-organisation in microscaffolds (FLUID3EAMS), 2) 2D microcapillary arrays on a dipstick (Digital Dipstick), 3) a sliding microfluidic platform with cross-flow (Slip-X-Chip), and 4) compartmentalization by cutting of soft solid matter (Solidify & Cut). These methods were used in a wide range of applications. Within the area of smart materials, we applied FLUID3EAMS to synthesize materials with temperature-tuneable permeability and surface energy and to establish, in a well-controlled fashion, tissue-like materials in the form of 3D droplet interface bilayer networks. Solidify & Cut was used to form soft composites with a new type of magnetic behaviour, rotation-induced ferromagnetism, that allows easy reprogramming of the magnetization of magnetopolymers. Within the area of medical diagnostics, we applied Digital Dipstick to perform rapid digital bacterial culture in a dipstick format and obtained clinically relevant diagnostic results on samples from patients with a urinary tract infection. Furthermore, Slip-X-Chip enables particle concentration and washing as new functions in sliding microfluidic platforms, which significantly expands their potential application area. Finally, within the area of cell therapy, we explored the microencapsulation of high concentrations of therapeutic cells and presented a novel technique to fabricate core-shell microcapsules by exploiting the superior material properties of spider silk membranes.
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| 3. |
- Liu, Zhenhua, 1992-
(författare)
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Droplet Acoustofluidics for Biochemical Applications
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Droplet microfluidics is a promising platform for biochemical applications where compartmentalized droplets serve as individual vials. Droplets are formed by using two immiscible phases, the continuous phase and the dispersed phase, making up the droplets. Droplets are interesting because they can provide fast, parallel reactions with low reagent consumption. Microscale particles, such as cells, can be encapsulated in the droplets and chemical reagents can be added via a pico-injector. However, removal of droplet background signal is hard to achieved by conventional methods, especially if you do not want to risk losing the encapsulated cells. In this thesis, I present a droplet microfluidic system that can achieve this, via droplet-internal particle manipulation using acoustophoresis.This droplet microfluidic system contains pico-injection and droplet split with acoustophoresis. The pico-injection is used to add fresh solution into the droplets and the droplet split with acoustophoresis is used to remove the droplet supernatant. With the combination of the pico-injector and the droplet split, the background signal of the droplets can be reduced and the cell medium in the droplets can be exchanged. This droplet microfluidic system can also be used to control timing of enzyme reactions by initiating the reaction by adding enzyme-coupled beads via the pico-injector and taking a sample from the droplets at specific time points via side channels. In this work, I have also investigated how the design of the droplet split could be optimized to obtain high particle recovery and enrichment. Finally, acoustic properties of a selection of oils that can used as the continuous phase were mapped to optimize the droplet system for acoustophoresis.This thesis explores the biochemical applications performed by the droplet acoustofluidics, in-droplet time-controlled enzyme reaction and medium exchange for in-droplet cell culture. Furthermore, the droplet acoustofluidics has the potential to study the reaction kinetics by other enzymes and achieve long-term in-droplet cell culture.
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| 4. |
- Trossbach, Martin
(författare)
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Strength in Numbers – Droplet Microfluidics for Multicellular Ensemble Applications
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The work presented in this doctoral thesis explores multicellular, biological, and biotechnological applications for microfluidic droplets, making use of a number of unique features of these miniaturized, highly scalable reaction vessels.Droplet microfluidics specializes in pico- to nanoliter sized aqueous droplets in an immiscible oil phase, borrowing techniques from the field of microfluidics, namely fluid actuation, detection systems and electronic peripherals. A lot of these techniques have been made possible by discoveries and inventions originally developed for microelectronics and relate to the fabrication of micrometer scale features. Channels with a width and depth of fractions of a millimeter allow for the reliable and precise manipulation of fluids necessary to achieve high throughput while maintaining accuracy.Many subdisciplines of biological research rely on scale, on strength in numbers, in a sense that only a sufficient number of samples enables insights into the genome, transcriptome, or proteome of an organism, into the heterogeneity of populations, into the efficacy of a prospective drug. Just like some other single-cell analysis techniques, such as flow cytometry, droplet microfluidics facilitates that scale of analysis. However, in addition to this, droplet microfluidics as a technology platform is capable of processing and analyzing multicellular ensembles, or interrogating extracellular traits. This is especially beneficial for biotechnological or pharmaceutical research applications.In Paper I, we investigated the encapsulation of insulin secreting cells in mucin gel beads. The gel protects the cells against a host’s immune system response while allowing for nutrient and gas passage as well as diffusion of the secreted insulin.In Paper II, we present a high-throughput production and analysis workflow for droplet-assisted spheroid formation. We use deep learning to train a model to support the optimization of droplet incubation conditions. The resulting minispheroids enable large-scale 3D cell culture model screening.In Paper III, we developed and characterized a portable, compact droplet generation setup, using exclusively commercially available parts and demonstrated its versatility by dynamically tuning droplet size and composition. Finally, we demonstrated its use for the encapsulation of human primary cells to form spheroids in the sterile environment of a biosafety cabinet.For Paper IV, we developed an integrated fluorescence area sorting approach to sort cell colonies in microfluidic droplets. After validating the sorter, we screened yeast microcolonies in droplets and used averaging over the entire droplet width to ameliorate the impact of cell heterogeneity within isoclonal populations.
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