Characterization of fluidic microassembly for immobilization and positioning of Drosophila embryos in 2-D arrays

A technique for the positioning and immobilization of Drosophila embryos in 2-D arrays for use in high throughput microinjection experiments has been characterized. The method is based on fluidic microassembly, and immobilization yield, the number of misplaced embryos, alignment properties, and adhesion force of the embryos have been measured for samples with four different pad geometries. For samples with 250 mum x 400 mum sized rectangular pads, an immobilization yield of 85% was achieved. The adhesion force of the embryos was estimated at 36 +/- 22 muN. A substantial amount of clustering was, however, observed. By reducing the pad size to 200 mum x 200 mum and changing the pad pitch and shape, the number of misplaced embryos was reduced to less than 5%. The adhesion force of embryos immobilized at the smaller pads was estimated at 14 +/- 5.5 muN, resulting in lower immobilization yield for these samples. The self-assembly process facilitates rotational alignment to some degree, and an average of 40% of the immobilized embryos align within +/-9degrees of the symmetry axis of the immobilization sites. (C) 2003 Elsevier B.V. All rights reserved.