A centrifugo-magnetically actuated gas micropump

This paper describes a novel gas micropump on a centrifugal microfluidic platform. The pump is integrated on a passive and microstructured polymer disk which is sealed with an elastomer lid featuring paramagnetic inlays. The rotational motion of this hybrid disk over a stationary magnet induces a designated sequence of volume displacements of the elastic lid, leading to a net transport of gas. The pumping pressure scales linearly with the frequency, with a maximum observable pressure of 4.1 kPa. The first application of this rotary device is the production of gas-liquid flows by pumping ambient air into a continuous centrifugal flow of liquid. The injected gas volume segments the liquid stream into a series of liquid compartments. Apart from such multi-phase flows, the new pumping technique supplements a generic air-to-liquid sampling method to centrifugal microfluidic platforms

A New Market-Based Approach to Securities Law

Modern securities regulation has three main areas, each of which is plagued by a core problem. Mandatory disclosure law leaves society with suboptimal disclosure, as the government calls for too little of some information (for example, management analysis of company prospects) and too much of other information (for example, data about trivial executive perks). Securities fraud law (specifically, its central fraud-on-the-market theory of reliance) yields damages at odds with any reasonable theory of compensation and deterrence. And insider trading law fails to achieve its ends because incentives to police illegal trading and tipping by executives are currently weak. In this Article, we propose fixing these fundamental flaws of securities law by shifting much of the regulatory focus from firms to information. In particular, we introduce the idea of building the law around a well-regulated market for the public-company information that sits at the center of each of the three main areas of securities law. Deploying this market, we argue, would trigger incentives for firms to disclose more information of value while also motivating them to more rigorously police illegal trading and tipping by their agents. Additionally, it would help regulators identify when the law requires disclosure that is not socially valuable and assist in the identification of a class of securities fraud plaintiffs that is more in line with the goals of the anti-fraud regime

Discrimination Platforms

Off-exchange trading today has become defined by its opacity. Indeed, the framing of this symposium on What Happens in the Dark: An Exploration of Dark Pools and High Frequency Trading and its goal of exam[ing] a portion of the modern market that remains largely outside of the public eye l is much in line with contemporary thinking in policymaking, academic, and industry circles alike. Yet, off-exchange trading through dark pools and the like is far more transparent than thought, and exchange trading the opposite. In fact, much trading through off-exchange platforms is even more transparent than that facilitated by exchanges. Despite these realities, the supposed contrast between exchange and off-exchange trading along this dimension continues to be highlighted-often along with a claim that it poses core securities-law problems. All the while, a clear-cut distinction between these two general types of trading platforms has gone relatively unnoticed: exchanges must welcome all traders, yet off-exchange platforms can engage in targeting and excluding. This trader-access distinction, I argue, should matter for those who care about the chief ends of modern securities law-and a good amount of the current transparency-distinction focus should therefore be reallocated toward the access one

Information Asymmetry and the Protection of Ordinary Investors

To some, the reductions in information asymmetry provided by the main securities-specific disclosure, fraud, and insider-trading laws help ordinary investors in meaningful ways. To others, whatever their larger social value, such reductions do little, if anything for these investors. For decades, these two sides of this investor-protection divide have mostly talked past each other. This Article builds on economic theory to reveal something striking: The reductions in information asymmetry provided by the core securities laws likely impose a long-overlooked cost on buy-and-hold ordinary investors. More specifically, I explain why there is much reason to believe that the reductions take away investment return from these investors, while providing them with only limited benefits. Thus, the article presents a serious challenge to conventional wisdom on information asymmetry and the protection of ordinary investors, and argues in favor of a shift in investor-protection efforts away from the main securities laws and to areas of regulation that have received relatively little attention to date

Alginate micro-bead fabrication on a centrifugal microfluidics platform

We present a novel method for the direct, centrifugally induced fabrication of small alginate beads displaying adjustable diameters between 180 mum and 800 mum by polymer-tube micronozzles. The size distribution features a CV of 7 - 16 % for the main peak. Up to 600 beads per second and channel are issued from the micronozzle through an air gap towards a standard lab tube ("Eppi") attached to the rotor spinning and containing a curing agent. At spinning frequencies between 5 Hz and 28 Hz, the tubes align horizontally under rotation and return to a vertical position as soon as the rotor is at rest. The hardened beads are collected within the tube for further processing or characterization. This method is considered as a low cost technology for micro encapsulation technologies

Aliquoting structure for centrifugal microfluidics based on a new pneumatic valve

We present a new microvalve that can be monolithically integrated in centrifugally driven lab-on-a-chip systems. In contrast to existing operation principles that use hydrophobic patches, geometrically defined capillary stops or siphons, here we present a pneumatic principle. It needs neither additional local coatings nor expensive micro sized geometries. The valve is controlled by the spinning frequency and can be switched to be open when the centrifugal pressure overcomes the pneumatic pressure inside an unvented reaction cavity. We designed and characterized valves ranging in centrifugal burst pressure from 6700 Pa to 2100 Pa. Based on this valving principle we present a new structure for aliquoting of liquids. We experimentally demonstrated this by splitting 105 muL volumes into 16 aliquots with a volume CV of 3 %

A New Market-Based Approach to Securities Law

Modern securities regulation has three main areas, each of which is plagued by a core problem. Mandatory disclosure law leaves society with suboptimal disclosure, as the government calls for too little of some information (for example, management analysis of company prospects) and too much of other information (for example, data about trivial executive perks). Securities fraud law (specifically, its central fraud-on-the-market theory of reliance) yields damages at odds with any reasonable theory of compensation and deterrence. And insider trading law fails to achieve its ends because incentives to police illegal trading and tipping by executives are currently weak. In this Article, we propose fixing these fundamental flaws of securities law by shifting much of the regulatory focus from firms to information. In particular, we introduce the idea of building the law around a well-regulated market for the publiccompany information that sits at the center of each of the three main areas of securities law. Deploying this market, we argue, would trigger incentives for firms to disclose more information of value while also motivating them to more rigorously police illegal trading and tipping by their agents. Additionally, it would help regulators identify when the law requires disclosure that is not socially valuable and assist in the identification of a class of securities fraud plaintiffs that is more in line with the goals of the anti-fraud regime