Labs-on-a-chip to Detect Milk Contamination

Investigator David Beebe, Ph.D., of the University of Wisconsin-Madison has developed a process to make on-demand, miniature sensors for a wide variety of poisons, including naturally occurring contaminants and intentionally introduced toxins. These would improve on the current system of tamper-resistant lids and sell by dates.

The sensors can be constructed to test for a particular toxin in as little as an hour with test results available in minutes.

The Wisconsin group, with Department of Homeland Security funding, is focusing on the nation's milk supply, which comes from a widely dispersed system in which large amounts of the highly perishable product are quickly collected and distributed. With a short cow-to-consumer timeline, contamination could affect large numbers of people before being detected. It might be possible, however, to incorporate sensors in food packaging that could tell if the package is disturbed or the contents are contaminated.

Beebe's group reported in a paper to be published in the journal Electrophoresis that disposable sensors can be manufactured on-demand in an inexpensive process. With collaborator Eric Johnson, Beebe tested the technique to rapidly detect botulism neurotoxin, considered to be a possible bioterrorism agent.


The botulinum toxin can be detected in blood or food using a standard test that takes up to four days to produce results. But the only treatment is an antitoxin that must be given right away. A lab-on-a-chip could produce faster results for more rapid treatment.

Beebe's design and fabrication process, which he calls microfluidic tectonics, uses light to freeze a liquid into the solid shape of a component, such as a valve, in the precise physical location where the component is needed.

Beebe's modular approach allows the flexibility to design and fabricate a wide range of test chips from a single toolbox of components.

'Multiple functions such as diluting and mixing blood, separating whole blood to serum and cells, and detecting botulinum toxin in the serum are performed in the device,' the researchers reported.

The device needs no power supply and uses no electronic parts. A blood sample is placed in a chamber on the chip and then the test set into motion by squeezing the chamber. Positive results appear as a color change visible to the naked eye.