Researchers at University of Texas at Austin have developed a self-powered sensor that can help in diagnosing pancreatitis. The device is built out of cheap parts, with the 13 cent LED, that lights up when trypsin in a blood sample is detected, probably being the most expensive component.
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, an 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 Reynold’s 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 diagnosed.
Press release: Self-powered, Blood-activated Sensor Detects Pancreatitis Quickly and Cheaply…
Abstract in Analytical Chemistry: Self-Powered Sensor for Naked-Eye Detection of Serum Trypsin
(hat tip: The Engineer)