Microfluidic manipulation via Marangoni forces

A convective flow system is engendered when two liquid droplets, or a liquid droplet and a solid surface, are maintained at different temperatures. Such flows give rise to Marangoni forces which under proper conditions prevent droplet coalescence, cause fluid motion, and dewetting. We present a study of adsorbed and applied fluid movement on a solid surface driven by surface tension gradients created by thermal gradients. Flexible control over the silicone oil and 1,3,5-trinitrotoluene movement is accomplished with an array of individually controllable gold thin film thermal elements on a fused silica substrate surface. We thus demonstrate unlimited fluid movements in one dimension. (C) 2004 American Institute of Physics.