NiOX Template-Grown Ni-MOF-Coated Carbon Paper Electrode Embedded Extended Gate Field Effect Transistor for Glucose Detection in Saliva: En Route toward the Noninvasive Diagnosis of Diabetes Mellitus

Our present work focuses on the developmentof nickeloxalate (NiOX)template-assisted growth of a nickel-metal organic framework(Ni-MOF) with sheetlike morphology on carbon paper (CP) electrodefor the noninvasive detection of glucose. We have utilized an extendedgate field effect transistor (EGFET) where the Ni-MOF/CP electrodeserves as the extended gate of a commercial n-type metal oxide semiconductorFET for sensing glucose. The electrode detects glucose concentrationsranging from 20 & mu;M to 1.47 mM. The sensor operates at a voltageof 0.7 V in the physiologically relevant electrolyte of phosphate-bufferedsaline (PBS) with a response time of less than 5 s. The sensitivityis calculated as 86 & mu;A mM(-1) cm(-2) from the linear region of the sensor response to the glucose concentration(20 & mu;M to 0.27 mM). Also, Ni-MOF/CP has shown a good selectiveresponse toward glucose against uric acid, sucrose, fructose, andascorbic acid. Additionally, the glucose sensing mechanism is investigatedthrough work function changes of the sensing electrode using a scanningKelvin probe. Real-time sample testing has revealed that the sensorpreserves the sensitivity in human saliva too. In summary, we concludethat the Ni-MOF/CP extended gate electrode EGFET is an alternativedevice for salivary glucose detection toward the noninvasive diagnosisof diabetes mellitus that can identify hyperglycemic, normal, andhypoglycemic conditions.