Abstract: A security device that exhibits at least one dynamic response upon change of orientation of the security device with respect to gravity, wherein the security device includes a hollow capsule completely filled with a liquid and one or more microscopic elements. In addition, the dynamic response continues after cessation of the change of orientation with respect to gravity. The dynamic response includes a transition of the one or more microscopic elements from substantial mechanical equilibrium to non-equilibrium upon action of the change of orientation with respect to gravity and back to substantial mechanical equilibrium after cessation of the change of orientation with respect to gravity. During the dynamic response, the one or more microscopic elements undergo at least one of a rotational motion and a translational motion relative to the liquid.

Abstract: A technique for detection of probes in a microfluidic flow-through chamber involves a plurality of interface pinning reaction vessel formed by micro- or nano-structured relief patterning of a substrate. The relief patterning increases a surface area locally, and defines a plurality of separated interface pinning reaction vessels. The marked detection protocol may be supplied on a single layer of a stacked microfluidic chip, or the chamber may constitute a whole layer. The chip may be designed to be driven mechanically, pneumatically, hydraulically, centrifugally or by capillary action. Each vessel allows for a high density of probes, an effective region for developer-type or fluorescence-based marking, and efficient readout. Suitable probe liquids can be self-limiting to fill one vessel. Suitable developer liquids avoid dye bleeding across vessels during washing.

Abstract: A security device that exhibits at least one dynamic response upon change of orientation of the security device with respect to gravity, wherein the security device includes a hollow capsule completely filled with a liquid and one or more microscopic elements. In addition, the dynamic response continues after cessation of the change of orientation with respect to gravity. The dynamic response includes a transition of the one or more microscopic elements from substantial mechanical equilibrium to non-equilibrium upon action of the change of orientation with respect to gravity and back to substantial mechanical equilibrium after cessation of the change of orientation with respect to gravity. During the dynamic response, the one or more microscopic elements undergo at least one of a rotational motion and a translational motion relative to the liquid.

Abstract: A security device that elicits at least one dynamic response upon acceleration, or upon change of orientation with respect to gravity, wherein the dynamic response continues after cessation of the acceleration or the change of orientation. In addition, the dynamic response can be optical, such that it is visually observable by an unaided human eye. Alternatively, the response can be machine readable. In some cases, the dynamic response has duration of from about 0.01 s to about 100 s, or from about Is to about 10 s.

Abstract: Gravitational Janus microparticle having, a center-of-mass, a center-of-volume, and a non¬uniform density, wherein: the center-of-mass and the center-of-volume are distinct. When suspended in a fluid, the microparticle substantially aligns with either: i) the gravitational field; or ii) the direction of an acceleration, such that the Janus microparticle is in substantial rotation equilibrium. After perturbation from substantial rotational equilibrium, the Janus microparticle reversibly rotates to return to substantial rotational equilibrium. The gravitational Janus microparticle may comprise at least two portions, each having distinct physical and/or chemical characteristics, wherein at least one portion provides a detectable effect following rotation and alignment of the microparticle.

Abstract: Gravitational Janus microparticle having, a center-of-mass, a center-of-volume, and a non-uniform density, wherein: the center-of-mass and the center-of-volume are distinct. When suspended in a fluid, the microparticle substantially aligns with either: i) the gravitational field; or ii) the direction of an acceleration, such that the Janus microparticle is in substantial rotation equilibrium. After perturbation from substantial rotational equilibrium, the Janus microparticle reversibly rotates to return to substantial rotational equilibrium. The gravitational Janus microparticle may comprise at least two portions, each having distinct physical and/or chemical characteristics, wherein at least one portion provides a detectable effect following rotation and alignment of the microparticle.

Abstract: A security device that elicits at least one dynamic response upon acceleration, or upon change of orientation with respect to gravity, wherein the dynamic response continues after cessation of the acceleration or the change of orientation. In addition, the dynamic response can be optical, such that it is visually observable by an unaided human eye. Alternatively, the response can be machine readable. In some cases, the dynamic response has duration of from about 0.01 s to about 100 s, or from about Is to about 10 s.