Layer-by-Layer Films with CoFe2O4Nanocrystals and Graphene Oxide as a Sensitive Interface in Capacitive Field-Effect Devices

ACS Applied Nano Materials, vol. 5, pp. 5258–5267

Abstract

Sensor devices have proved to be a promising technology for portable microelectronic systems for biomedical and environmental applications. Depending on the target analyte and/or the sensor platform chosen, the study of (nano)materials and their ideal incorporation in the device as a receptor layer have great importance for developing sensing units with enhanced properties and performance. Here, we employed the layer-by-layer (LbL) technique to fabricate nanostructured films as sensing units for detecting H 2 O 2 and heavy metal ions (Cd 2+ and Cu 2+ ). The LbL film was deposited on electrolyte–insulator–semiconductor (EIS) field-effect devices, combining CoFe 2 O 4 nanocrystals embedded into polyallylamine hydrochloride (PAH) and graphene oxide (GO) as a PAH-CoFe 2 O 4 /GO structure. Scanning electron microscopy revealed a LbL film morphology with high surface area presenting heterogeneous clusters of nanocrystals covered by a homogeneous coating of GO. The electrochemical characterization to monitor the film growth and the sensing properties for detecting H 2 O 2 and Cd 2+ and Cu 2+ ions was carried out by capacitance–voltage ( C / V ) and constant-capacitance (ConCap) measurements. The results demonstrated catalytic features in detection experiments for an optimized EIS-LbL sensor containing a 6-bilayer PAH-CoFe 2 O 4 /GO LbL film. This sensor system was sensitive for all analytes and exhibited a low limit of detection of ca. 314.3 μM for H 2 O 2 and 0.54 and 0.47 μM for Cd 2+ and Cu 2+ ions, respectively. These findings prove the relevance of incorporating nanostructured films as a receptor layer to enhance sensing properties and may envisage a proof-of-concept field-effect sensor system for environmental applications.

Authors 4

1. Paulo Vitor de Morais

   Universidade Estadual Paulista (Unesp) · Universidade Federal do Triângulo Mineiro

   Affiliation as printed

   Interdisciplinary Laboratory of Electrochemistry and Ceramics, Chemistry Institute, São Paulo State University, 14800-900 Araraquara, SP, Brazil

   Laboratory of Applied Nanomaterials and Nanostructures (LANNA), Institute of Exact Sciences, Natural and Education, Federal University of Triângulo Mineiro (UFTM), 38064-200 Uberaba, MG, Brazil

2. Marcelo Ornaghi Orlandi

   Universidade Estadual Paulista (Unesp)

   Affiliation as printed

   Interdisciplinary Laboratory of Electrochemistry and Ceramics, Chemistry Institute, São Paulo State University, 14800-900 Araraquara, SP, Brazil

3. Michael Josef Schöning Aachen Institute of Nano- and Biotechnologies (INB)

   FH Aachen · Forschungszentrum Jülich

   Affiliation as printed

   Institute of Biological Information Processing (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany

   Institute of Nano- and Biotechnologies (INB), FH Aachen, Campus Jülich, 52428 Jülich, Germany

4. José Roberto Siqueira Junior corresponding

   Universidade Federal do Triângulo Mineiro

   Affiliation as printed

   Laboratory of Applied Nanomaterials and Nanostructures (LANNA), Institute of Exact Sciences, Natural and Education, Federal University of Triângulo Mineiro (UFTM), 38064-200 Uberaba, MG, Brazil