Effect of contact angle hysteresis on thermocapillary droplet actuation

Open microfluidic devices based on actuation techniques such as electrowetting, dielectrophoresis, or thermocapillary stresses require controlled motion of small liquid droplets on the surface of glass or silicon substrates. In this article we explore the physical mechanisms affecting thermocapillary migration of droplets generated by surface temperature gradients on the supporting substrate. Using a combination of experiment and modeling, we investigate the behavior of the threshold force required for droplet mobilization and the speed after depinning as a function of the droplet size, the applied thermal gradient and the liquid material parameters. The experimental results are well described by a hydrodynamic model based on earlier work by Ford and Nadim. The model describes the steady motion of a two-dimensional droplet driven by thermocapillary stresses including contact angle hysteresis. The results of this study highlight the critical role of chemical or mechanical hysteresis and the need to reduce this retentive force for minimizing power requirements in microfluidic devices

Capacitive sensing of droplets for microfluidic devices based on thermocapillary actuation

The design and performance of a miniaturized coplanar capacitive sensor is presented whose electrode arrays can also function as resistive microheaters for thermocapillary actuation of liquid films and droplets. Optimal compromise between large capacitive signal and high spatial resolution is obtained for electrode widths comparable to the liquid film thickness measured, in agreement with supporting numerical simulations which include mutual capacitance effects. An interdigitated, variable width design, allowing for wider central electrodes, increases the capacitive signal for liquid structures with non-uniform height profiles. The capacitive resolution and time response of the current design is approximately 0.03 pF and 10 ms, respectively, which makes possible a number of sensing functions for nanoliter droplets. These include detection of droplet position, size, composition or percentage water uptake for hygroscopic liquids. Its rapid response time allows measurements of the rate of mass loss in evaporating droplets

Recent and upcoming BCI progress: overview, analysis, and recommendations

Brain–computer interfaces (BCIs) are finally moving out of the laboratory and beginning to gain acceptance in real-world situations. As BCIs gain attention with broader groups of users, including persons with different disabilities and healthy users, numerous practical questions gain importance. What are the most practical ways to detect and analyze brain activity in field settings? Which devices and applications are most useful for different people? How can we make BCIs more natural and sensitive, and how can BCI technologies improve usability? What are some general trends and issues, such as combining different BCIs or assessing and comparing performance? This book chapter provides an overview of the different sections of this book, providing a summary of how authors address these and other questions. We also present some predictions and recommendations that ensue from our experience from discussing these and other issues with our authors and other researchers and developers within the BCI community. We conclude that, although some directions are hard to predict, the field is definitely growing and changing rapidly, and will continue doing so in the next several years

Homotopy Relations for Topological VOA

We consider a parameter-dependent version of the homotopy associative part of the Lian-Zuckerman homotopy algebra and provide the interpretation of multilinear operations of this algebra in terms of integrals over certain polytopes. We explicitly prove the pentagon relation up to homotopy and propose a construction of higher operations.Comment: 15 pages, 1 figure, typos correcte

Analisis Kinerja Lalu Lintas Jalan Urip Sumoharjo YOGYAKARTA

Yogyakarta city in ones of the big city in java, that straregic because of tourism and student city. The every years vehicle to in Yogyakarta be increase. There is be the main of jamming trafgic, ones of them is Urip Sumoharjo street from STA 03+100 – STA 03+585. From a sekunder data from dirjen Bina Marga Yogyakarta show of digit traffic growth daily being increase for 4 last year. The number of street ministry feasibility show with degree of saturation (DS), with condition DS < 0,75. The result of the analysis from survey on September 2013 show DS to existing road not eliginle with grades DS 1,25 because park ib roads so width then effectife traffic decreased of road capacity. Main of step solution jamming traffic are park optimalitation, with manage parking patters with some simulation in cornerand length with the reduction of parking on-street along 240 m of the junction the Galeria Mall, to meet the needs of the SRP which is less need to create a new SRP for making buildings with parking in the surrounding streets Urip Sumoharjo. After then steep feel not optimal to change of DS for the next 4 years, make a building parking in arround of Urip Sumoharjo. With it capacity of road will be increase so DS what quality last a long time same with increase of growth LHR Yogyakarta city in next year