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Open AccessArticle

Performance-Enhanced Non-Enzymatic Glucose Sensor Based on Graphene-Heterostructure

1
Graduate Program in Nanotechnology, The American University in Cairo (AUC), New Cairo 11835, Egypt
2
Department of Mechanical Engineering, The American University in Cairo (AUC), New Cairo 11835, Egypt
3
Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Electrum 229, SE-16440 Kista, Sweden
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Swedish e-Science Research Center (SeRC), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
5
Department of Physics and Astronomy, Materials Theory Division, Uppsala University, Box 516, SE-75120 Uppsala, Sweden
*
Author to whom correspondence should be addressed.
Sensors 2020, 20(1), 145; https://doi.org/10.3390/s20010145
Received: 28 November 2019 / Revised: 16 December 2019 / Accepted: 20 December 2019 / Published: 24 December 2019
(This article belongs to the Special Issue Graphene-Based Materials for Electrochemical Sensing)
Non-enzymatic glucose sensing is a crucial field of study because of the current market demand. This study proposes a novel design of glucose sensor with enhanced selectivity and sensitivity by using graphene Schottky diodes, which is composed of graphene (G)/platinum oxide (PtO)/n-silicon (Si) heterostructure. The sensor was tested with different glucose concentrations and interfering solutions to investigate its sensitivity and selectivity. Different structures of the device were studied by adjusting the platinum oxide film thickness to investigate its catalytic activity. It was found that the film thickness plays a significant role in the efficiency of glucose oxidation and hence in overall device sensitivity. 0.8–2 μA output current was obtained in the case of 4–10 mM with a sensitivity of 0.2 μA/mM.cm2. Besides, results have shown that 0.8 μA and 15 μA were obtained by testing 4 mM glucose on two different PtO thicknesses, 30 nm and 50 nm, respectively. The sensitivity of the device was enhanced by 150% (i.e., up to 30 μA/mM.cm2) by increasing the PtO layer thickness. This was attributed to both the increase of the number of active sites for glucose oxidation as well as the increase in the graphene layer thickness, which leads to enhanced charge carriers concentration and mobility. Moreover, theoretical investigations were conducted using the density function theory (DFT) to understand the detection method and the origins of selectivity better. The working principle of the sensors puts it in a competitive position with other non-enzymatic glucose sensors. DFT calculations provided a qualitative explanation of the charge distribution across the graphene sheet within a system of a platinum substrate with D-glucose molecules above. The proposed G/PtO/n-Si heterostructure has proven to satisfy these factors, which opens the door for further developments of more reliable non-enzymatic glucometers for continuous glucose monitoring systems. View Full-Text
Keywords: graphene; electrochemical; biosensor; heterostructure; non-enzymatic; Schottky diode; glucose; glucometers; ALD; PtO graphene; electrochemical; biosensor; heterostructure; non-enzymatic; Schottky diode; glucose; glucometers; ALD; PtO
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MDPI and ACS Style

Sakr, M.A.; Elgammal, K.; Delin, A.; Serry, M. Performance-Enhanced Non-Enzymatic Glucose Sensor Based on Graphene-Heterostructure. Sensors 2020, 20, 145.

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