Liquid handling using expandable microspheres

In this study we introduce two novel concepts for fluid handling in microfluidic systems and show their realization in micromachined test structures: a one-shot micropump and a normally open one-shot valve. Both principles use Expancel/spl reg/ microspheres, which are small spherical plastic particles that, when heated, increase their volume by a factor of about 60. The expansion is irreversible, i.e. when cooled again, the expandable microspheres do not shrink.