Mediator-free microfluidics biosensor based on titania–zirconia nanocomposite for urea detection

Abstract

Urease (Urs) and glutamate dehydrogenase (GLDH) co-immobilized onto titania–zirconia (TiO₂–ZrO₂) nanocomposite and integrated with microfluidics mediator-free sensor have been utilized for urea detection. The PDMS microchannels have been sealed with a glass substrate comprising of reference (Ag/AgCl), counter (ITO) and working (Urs-GLDH/TiO₂-ZrO₂/ITO) electrodes. This mediator-free microfluidics urea sensor shows linearity as 5–100 mg/dL with improved sensitivity as 2.74 μA [Log mM]⁻¹ cm⁻² and detection limit of 0.07 mg/dl (0.44 mM) using 3σ_b/m criteria. The Reynolds number has been found to be as 0.166, indicating that fluid flow is completely laminar, controllable and the pressure drop across the microchannels is found to be as 3.5 × 10³ Pa.