Silicon lens arrays for wafer level packaging of IR-sensors

A new process technology has been developed for a cost efficient production of refractive convex lenses made of silicon. These lenses are produced as lens arrays on standard eight inch Si-wafers to allow the optical capping of IR sensors in a wafer level packaging (WLP) process. A manufacturing process is described using a glass forming process with thin (50um) AF32® glass wafers. Si-spheres of well-defined diameter are transferred to a thin glass membrane on top of a Si-wafer with prefabricated cylindrical openings. In a thermal bonding process, the lens part of the Si-spheres sinks into the cavities while the outer part is grinded away. The resulting plano-convex lens calottes remain firmly embedded in the wafer surface. In this manner an array of Si-lenses on a Si-wafer is realized to be used as cover wafer for wafer level packaging of IR-sensor devices. First designs of Si-lens arrays have been fabricated. Starting with Si-spheres of radius of curvature 0.8 mm conv ex lenses of 0.82 mm diameter (aperture) and a sagittal height of 0.12 mm were produced

Reproductive strategies and population structure in Leishmania : substantial amount of sex in Leishmania Viannia guyanensis

Leishmania species of the subgenus Viannia and especially Leishmania Viannia guyanensis are responsible for a large proportion of New World leishmaniasis cases. Since a recent publication on Leishmania Viannia braziliensis, the debate on the mode of reproduction of Leishmania parasites has been reopened. A predominant endogamic reproductive mode (mating with relatives), together with strong Wahlund effects (sampling of strains from heterogeneous subpopulations), was indeed evidenced. To determine whether this hypothesis can be generalized to other Leishmania Viannia species, we performed a population genetic study on 153 human strains of L. (V.) guyanensis from French Guiana based on 12 microsatellite loci. The results revealed important homozygosity and very modest linkage disequilibrium, which is in agreement with a high level of sexual recombination and substantial endogamy. These results also revealed a significant isolation by distance with relatively small neighbourhoods and hence substantial viscosity of Leishmania populations in French Guiana. These results are of epidemiological relevance and suggest a major role for natural hosts and/or vectors in parasite strain diffusion across the country as compared to human hosts