The HP D300 digital dispenser allow ultra-low volume (pL-nL droplets) delivery of DMSO solubilized (or suspended) test materials. High dilutions can be delivered directly into medium & cell containing multi-well plates, obverting the need for multiple DMSO-based stock solutions.  The dispensing of patterns of droplets allows exposure of ALI cultures using volumes of only nL to µL to the apical surface of tissues. Ciliated cultures quickly mix the test materials in the mucus layer to achieve a homogenous exposure to the epithelium.