Microfluidics at SDSU’s Science Sampler

On Saturday (March 23rd) SDSU held its annual Science Sampler; a showcase of fun science activities for families to experience. This year our lab was part of the event!

We wanted to demonstrate some simple analytical devices that can do some rather accurate measurements. So we prepared some paper based microfluidic devices. These were made from chromatography paper, and each arm was loaded with increasing amounts of base, and an indicator dye at the end. The paper was sealed with clear masking tape, and one arm dipped into an acidic solution. Capillary action and chemistry does the rest. In a few minutes you have a rough titration of the acid!

Below is a slideshow of our device being used to titration a 0.5M solution of a weak acid. The titrant wells are filled with increasing concentration of KOH, and the indicator zones have phenolphthalein. Each zone required only 3 micro liters of solution!

For a somewhat less quantitative, but more visually appealing (and kid pleasing) titration the phenolphthalein can be replaced with universal indicator.

Acid base titration on a paper device with universal indicator in the detection zones.