Acute pancreatitis is a sudden inflammation of the pancreas that can lead to severe stomach pain, nausea, fever, shock and in some cases, death. Richard Crooks and Brian Zaccheo, University of Texas, Austin, USA, have developed a sensor to detect trypsin, an enzyme which hydrolyses proteins and that is overabundant in the blood of patients with acute pancreatitis.

The sensor takes the form of a Mg//Fe³⁺ galvanic cell with passive protein layer made of gelatine and a layer of aluminium foil which block Mg oxidation at the anode. Trypsin in a blood sample breaks down the gelatin barrier in the sensor. Application of NaOH then corrodes the Al foil and a circuit is formed between the Mg anode and the cathode. This generates current to light the LED. In the absence of trypsin, the NaOH penetrates the gelatine layer more slowly and LED illumination is delayed.

The sensor can give a diagnosis in 3 hours and it has a limit of detection is 0.5 μg/mL, which is sufficiently low for detection of pathological conditions. In addition to its potential applications in hospitals, its low cost and lack of external power requirement makes it ideal for locations without reliable power such as developing countries, remote locations or disaster areas.

• Self-Powered Sensor for Naked-Eye Detection of Serum Trypsin
  B. A. Zaccheo, R. M. Crooks,
  Anal. Chem. 2011, 83(4), 1185–1188.
  DOI: 10.1021/ac103115z