30 years of microfluidics

Microfluidics provides a great opportunity to create devices capable of outperforming classical techniques in biomedical and chemical research. In this review, the origins of this emerging field in the microelectronics industry are detailed. We also appraise how factors such as government funding influenced the development of new materials and fabrication techniques. Current applications of microfluidics are also examined and we highlight areas where work should be focussed in the future to ensure that the technology realises its full potential

Rapid prototyping of injection moulded microfluidics with in-built sensing

Microfluidics have been utilised over the past few decades to realise a wide range of academic research. These fluidic devices carry several advantages over classical analytical techniques such as lower reagent consumption, more rapid reactions, and increased sensitivity. However, while many of the currently used fabrication techniques allow for the rapid prototyping of microfluidic structures, these methods, and the design rules associated with them, do not translate well into mass-producible devices. For example, devices can be manufactured rapidly using soft lithography methods however, this requires access to specialist clean-room facilities and the through-put is limited to only a handful of devices per day. To address this, the work in this thesis focuses on developing a manufacturing platform that allows for the rapid prototyping of microfluidic devices using injection moulding. This process not only allows for the fabrication of hundreds of devices per day, but also allows for the use of materials such as polystyrene which have material properties that are better suited for applications such as cell culture. To achieve this, 3D printed inlays were evaluated for use in an industrial injection moulding machine and it was found that channels as small as 100 x 200 μm could be reliably manufactured. To complement this manufacturing platform, an oxygen sensor was also demonstrated that could be rapidly incorporated into the microfluidic devices without the requirement of clean-room facilities. This sensor could detect oxygen with high enough spatial and temporal resolution for most cell culture applications. Alongside this, steps towards making a device for measuring cell barrier integrity were also made. This work showed how functional elements such as electrodes and membranes could be rapidly incorporated into the injection moulded devices. However, a full demonstration of working trans-epithelial/endothelial-resistance measurements was not achieved. Overall this work demonstrates a novel manufacturing platform that should enable a more seamless transition from prototype, to mass-produced microfluidic devices in the future

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

Direct Evidence for Packaging Signal-Mediated Assembly of Bacteriophage MS2

Using cross-linking coupled to matrix-assisted laser desorption/ionization mass spectrometry and CLIP-Seq sequencing, we determined the peptide and oligonucleotide sequences at the interfaces between the capsid proteins and the genomic RNA of bacteriophage MS2. The results suggest that the same coat protein (CP)-RNA and maturation protein (MP)-RNA interfaces are used in every viral particle. The portions of the viral RNA in contact with CP subunits span the genome, consistent with a large number of discrete and similar contacts within each particle. Many of these sites match previous predictions of the locations of multiple, dispersed and degenerate RNA sites with cognate CP affinity termed packaging signals (PSs). Chemical RNA footprinting was used to compare the secondary structures of protein-free genomic fragments and the RNA in the virion. Some PSs are partially present in protein-free RNA but others would need to refold from their dominant solution conformations to form the contacts identified in the virion. The RNA-binding peptides within the MP map to two sections of the N-terminal half of the protein. Comparison of MP sequences from related phages suggests a similar arrangement of RNA-binding sites, although these N-terminal regions have only limited sequence conservation. In contrast, the sequences of the C-termini are highly conserved, consistent with them encompassing pilin-binding domains required for initial contact with host cells. These results provide independent and unambiguous support for the assembly of MS2 virions via a PS-mediated mechanism involving a series of induced-fit viral protein interactions with RNA

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

3D printed tooling for injection moulded microfluidics

Microfluidics have been used for several decades to conduct a wide range of research in chemistry and the life sciences. The reduced dimensions of these devices give them advantages over classical analysis techniques such as increased sensitivity, shorter analysis times, and lower reagent consumption. However, current manufacturing processes for microfluidic chips either limits them to materials with unwanted properties, or are not cost effective enough for rapid-prototyping approaches. Here we show that inlays for injection moulding can be 3D printed, thus reducing the skills, cost, and time required for tool fabrication. We demonstrate the importance of orientation of the part during 3D printing so that features as small as 100 x 200 μm can be printed. We also demonstrate that the 3D printed inlay is durable enough to fabricate at least 500 parts. Furthermore, devices can be designed, manufactured, and tested within one working day. Finally, as demonstrators we design and mould a microfluidic chip to house a plasmonic biosensor as well as a device to house liver organoids showing how such chips can be used in organ-on-a-chip applications. This new fabrication technique bridges the gap between small production and industrial scale manufacturing, whilst making microfluidics cheaper, and more widely accessible

Large volume nanoscale 3D printing: Nano-3DP

3D printers suffer from the inverse relationship between throughput and minimum feature size; with smaller features inducing a cubic increase in print time. Here we introduce Nano-3DP, a hybrid process that combines digital light projection 3D printing with nanoscale-relief patterning. The tool enables large volume (cm3) prints with nanoscale details at a truly rapid rate (~120 mm/hour). 40 nm features, half the size of the finest printed details to date, are produced across a scalable print volume. We address the intrinsic issues of throughput and pixel induced surface inhomogeneity. To demonstrate the unique potential realized by this printing method across different areas of science optical lenses, injection molding tools and bio-implants originally acquired by x-ray CT are produced with functional nanoscale surface details. Notably, in vitro bone cell analysis delivered a profound 4.5-fold increase in osteogenesis purely through the inclusion of nanoscale features on the printed surfaces