Microfluidic device for robust generation of two-component liquid-in-air slugs with individually controlled composition

Using liquid slugs as microreactors and microvessels enable precise control over the conditions of their contents on short-time scales for a wide variety of applications. Particularly for screening applications, there is a need for control of slug parameters such as size and composition. We describe a new microfluidic approach for creating slugs in air, each comprising a size and composition that can be selected individually for each slug. Two-component slugs are formed by first metering the desired volume of each reagent, merging the two volumes into an end-to-end slug, and propelling the slug to induce mixing. Volume control is achieved by a novel mechanism: two closed chambers on the chip are initially filled with air, and a valve in each is briefly opened to admit one of the reagents. The pressure of each reagent can be individually selected and determines the amount of air compression, and thus the amount of liquid that is admitted into each chamber. We describe the theory of operation, characterize the slug generation chip, and demonstrate the creation of slugs of different compositions. The use of microvalves in this approach enables robust operation with different liquids, and also enables one to work with extremely small samples, even down to a few slug volumes. The latter is important for applications involving precious reagents such as optimizing the reaction conditions for radiolabeling biological molecules as tracers for positron emission tomography

Thigh-length compression stockings and DVT after stroke

Controversy exists as to whether neoadjuvant chemotherapy improves survival in patients with invasive bladder cancer, despite randomised controlled trials of more than 3000 patients. We undertook a systematic review and meta-analysis to assess the effect of such treatment on survival in patients with this disease

Improving post-EVAR surveillance with a smart stent-graft

Abdominal aortic aneurysms (AAA or triple A’s) are indolent and deadly diseases. Their treatment options involve either an invasive procedure or a minimally invasive one. When the minimally invasive procedure, endovascular aneurysm repair (EVAR), was introduced, it revolutionized the treatment of AAA’s due to advantages such as shortened hospital stays and reduced costs. As EVAR requires periodic imaging exams, questions are nowadays being raised regarding the procedure’s long-term cost-benefit relation. In order to reduce followup costs, new technological solutions are being pursued, namely EVAR stentgrafts with sensing capabilities. In this chapter, the suitability of aneurysm sac pressure measurement for EVAR surveillance is evaluated using an AAA computer model. In addition the design drivers underlying EVAR stent-grafts are reviewed and the development of a new flexible pressure sensor integrated into a stent-graft is described.Fundação para a Ciência e a Tecnologia (FCT