Trehalose is a dimer of two glucose molecules and has recently been shown to help retain the functional stability of enzymes [25]. Among sugars, trehalose has been known for its superior ability in protecting enzyme activity. Thus we tested the effect of trehalose on the stability of our biosensor up to 8% (w/v) (Figure 5(b)). The results showed that trehalose stabilized the enzyme and improved the stability by 10% for 10% of trehalose, but not as much as glucose. Thus glucose was chosen as the stabilizer compound for the rest of the studies. The final format of the biosensor included one additional compound for protection against microorganisms during storage. Sodium azide is an antibacterial agent, commonly used in the biosensor developments. In this study, 0.02% (w/v) sodium azide was used for its antibacterial effect, and the possible effect on the activity of the enzyme was experimented. 0.02% sodium azide did not have a negative effect on the performance of biosensor (results are not shown). Therefore it was concluded that sodium azide could be used as antibacterial agent in the biosensor.