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PUNCH CARD Programmable Microfluidics holds the promise of bringing more science out of the research lab and into the developing world. It could also be a lot of fun encouraging kids to learn chemistry.


Manu Prakash, Assistant Professor of Bioengineering, Affiliate at Stanford Woods Institute for the Environment, Stanford University.

It began with a gift exchange: The wife of Stanford bioengineering professor Manu Prakash came home with a hand-cranked music box, the kind with a set of pins on concentric disks. This music box got Prakash thinking about a hand-held programmable device capable of performing experiments by metering and mixing droplets of chemicals.


Microfluidic chip used for testing drug reactions. It was developed by researchers in 2009 at the University of Twente in the Netherlands. Image from

Small silicon chips already exist with tiny valves and channels for manipulating droplets of fluids. These are called microfluidic chips, common in research labs but often requiring expensive support equipment.

Prakash got Stanford graduate student George Korir involved in combining the sophistication of microfluidics with the low-cost hand-held programmable features of a music box.


The Prakash/Korir programmable microfluidic system. This and other images from their research paper,

Their prototype uses a hand-cranked wheel to feed a paper tape punched with coded instructions past a series of pins. When a pin encounters a hole, it flips and activates one of the microfluidic chip’s tiny pumps or valves.


A microfluidic chip’s pump in action: A gear tooth of the actuator/driver collapses a microchannel. This pinch point pushes fluid along its path.

Their prototype has 15 independent pumps, valves and droplet generators, each controlled by the coded instructions in the paper tape. Progress of the experiment can be seen through the transparent chip.

A change of paper tape sets a different process with the same microfluidic chip’s chemicals. A change of chip introduces different chemicals and channels for other experiments. Prakash and Korir believe the device could be made from inexpensive, durable materials costing less than $5.

As an example of its use, a microfluidic chip could be loaded with chemicals used in water testing, its device programmed to detect contaminants, pH or the presence of microorganisms. Afterward, the chip could be rinsed out and reused with a new batch of chemicals.

Other applications range from medical diagnostics to soil testing to the analysis of snake-bite venom. All that’s needed is the appropriate choice of chemicals in the chip and programmed tape in the actuator/driver.

Prakash, born in India, and Korir, from Kenya, originally envisioned the device as a public health tool suitable for use in undeveloped areas. It could also be used in research labs for inexpensive testing.

Enter SPARK, the Science Play And Research Kit competition, co-sponsored by the Gordon and Betty Moore Foundation and the Society for Science & the Public Health. SPARK gave Prakash a $50,000 award toward developing the prototype into a low-cost product.


This computer-aided-design rendition shows the actuator/driver into which a microfluidic chip fits.

Prakash and Korir recall their childhoods, when playing with science experiments encouraged both to their academic careers. Notes Prakash, “It’s important to bring open-ended tools for discovery to a broad spectrum of users without dumbing down the tools.”

He and Korir imagine a kit for kids, with a few pre-punched tapes and several chips containing specific chemicals, channels, valves and pumps. Safety and cleanliness are enhanced by the fact that the chemicals never leave the chips. Kids eventually could be directed into punching their own tapes to program new experiments.

For more details, see Stanford News, It has a video as well showing the device in action. To see another of Prakash’s innovative science projects for kids (and inquisitive grownups too), check out It describes an origami-like construction that provides 2000X magnification for less than a dollar.

Like Punch Card Programmable Microfluidics, the Foldscope has yet to be commercially available. However, with SPARK and other encouragements, this could change. ds

© Dennis Simanaitis,, 2015

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