University of Texas at Austin

Tuesday, May 17, 2011

Developing a diagnostic device

Brian Zaccheo with his sensor for acute pancreatitis.

Brian Zaccheo with his sensor for acute pancreatitis.

When Brian Zaccheo designed a low-cost, self-powered diagnostic device for acute pancreatitis, he combined skills from his undergraduate training in biochemistry with the analytical chemistry expertise in the laboratory of his adviser, Prof. Richard Crooks.

But he added another element to the mix: business sense.

The result is a device that can be made cheaply with ingredients such as milk protein, gelatin, aluminum foil and LED lights.

It works quickly. Place a sample on the device and chemistry does the rest.

The kicker, as far as Zaccheo is concerned, is that the device is self-powered. The chemical processes that test the blood sample also work to turn on the light.

It can be used in places without medical infrastructure or reliable power.

The sensor could help prevent damage from acute pancreatitis, which is a sudden inflammation of the pancreas that can lead to severe stomach pain, nausea, fever, shock and in some cases, death.

“You can just imagine taking it out of a foil packet and with a couple of eye droppers” and putting it to work, Zaccheo, a Ph.D. candidate at The University of Texas at Austin, said.

This biosensor for detecting acute pancreatitis is cheap to make and easy to use.

This biosensor for detecting acute pancreatitis is cheap to make and easy to use.

In designing the device, Zaccheo’s guiding-light products were the glucose monitors used by people with diabetes and the home pregnancy test kit.

“These are the two titans of the bio-sensing field,” he said. “It would be amazing to come up with something that would be complementary to them, using similar kinds of technology, bringing diagnostics into the home or to environments that would otherwise be unable to do such complicated tests.”

Zaccheo kept the user in mind as he designed the device.

A light, he thought, would be a good way to indicate results.

“Light is something everyone is comfortable with,” he said. “It’s an obvious signal. If you’re going to have a sensor that gives a yes or a no answer there are very few things that people would be more comfortable with than light.”

For light, he turned to light-emitting diodes (LEDs), which are commonplace.

“We have them in all of our gadgets,” he said. “They’re in our computers. It’s something people are used to looking at.”

But LEDs require a large voltage, which might mean plugging the device into a power supply or developing a battery for it.

Here’s how the device works:

In step one, a bit of blood extract is dropped onto a layer of gelatin and milk protein. If there are high levels of trypsin, a digestive enzyme that is overabundant in the blood of patients with acute pancreatitis, the trypsin will break down the gelatin in much the same way it breaks down proteins in the stomach.

In step two, a drop of sodium hydroxide (lye) is added. If the trypsin levels were high enough to break down that first barrier, the sodium hydroxide can trickle down to the second barrier, a strip of Reynolds Wrap, and go to work dissolving it.

The foil corrodes, and with both barriers now permeable, a circuit is able to form between a magnesium anode and an iron salt at the cathode. Enough current is generated to light up a red LED. If the LED lights up within an hour, acute pancreatitis is indicated.

Zaccheo and Crooks published a describing the device in Analytical Chemistry.

“I credit Brian fully for identifying the need for this device, and then coming up with a very clever implementation,” Crooks said. “Of course, this is exactly what one hopes one’s students will be able to do when they reach the end of their doctoral studies.”

Zaccheo is to defend his dissertation this summer. Its central theme is finding ways to work with common materials in doing diagnostic medicine and make tests more robust, easier to use or usable in places without complicated lab infrastructure.

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