Influence of stress in ZnO thin films on its biosensing application

• Effect of growth induced intrinsic stress on biosensing response of ZnO studied.
• Induced stress varied by growing films under different ambient gas ratio.
• Biosensing response found to depend on physical properties of the thin film.
• Films with high intrinsic stress prove to be better for biosensing application.

Highly c-axis oriented zinc oxide (ZnO) thin films deposited by radio frequency (RF) magnetron sputtering, under varying ambient atmosphere (oxygen and argon reactive gas mixture), were studied for biosensing application. The as-grown ZnO thin films were found to be under compressive stress. Glucose oxidase was chosen as model enzyme for studying biosensing response properties of the ZnO thin films. The present study reveals a good correlation between stress induced during thin film growth and its biosensing response characteristic. The bio-electrodes based on ZnO thin films which are under the influence of higher stress, show better sensitivity and higher enzyme loading along with a prolonged shelf life. The study highlights the importance of physical properties of thin film matrix on its biosensing application.