Study of the Immobilized Papain Based on the Extended Gate Field Effect Transistor

As we known, laboratories and biotechnology companies focused on developing novel functional foods, health care products and biosensors technology in recent years. For example, the glucose sensors were a common technology of biosensors, and many of the health foods were produced by enzymes. Papain, the most popular enzyme, was obtained from papaya. The advantages of papain were that it helps digest the protein and controls the excessive acid in the stomach, and it also can beautify the features. In this study, we use the extended gate field effect transistor (EGFET) as the structure of papain biosensor. The EGFET has many advantages such as light insensitivity, simple to package, the flexibility of shape of the extended gate area and lower cost. The ruthenium oxide (RuO2) EGFET was fabricated by radiofrequency (R.F.) sputtering, the Ar gas flow was 40 sccm; O2 gas flow was 15 sccm, and the reaction pressure was 10 mTorr for 20 min and the R.E power was 100W at 13.56MHz. Immobilized papain on the different substrates of the EGFET as RuO2 and indium tin oxide (ITO) glass were investigated the characterization and sensitivity of papain biosensors. Additionally, the purpose of this experiment is to determine the optimum conditions of the immobilized papain on the EGFET, with developing low cost and disposable papain biosensors.