Electrophoretic-deposited HAP nano-layer as a QCM-D sensor coating: effects of suspension concentration and electric-field strength

Abstract

This study investigates the fabrication of hydroxyapatite (HAP) nano-coating on a gold–quartz crystal sensor used for quartz crystal microbalance with dissipation (QCM-D) measurement using an electrophoretic deposition technique. Surface morphology and thickness of the HAP coating are examined via scanning electron microscopy and nano-indention testing. Its repeatability is verified via QCM-D testing. Results show that electrophoretic deposition with ultrasonic treatment is feasible and cost-effective for fabricating nano-thick HAP coatings on a QCM-D gold–quartz crystal sensor surface. Both suspension concentration and electric-field strength influence the compactness of HAP coatings. There exists a non-linear relationship between HAP coating compactness and the suspension concentration/electric-field strength. When the HAP suspension concentration is 30 g/l and the applied electric-field strength is 150 V/cm, the HAP coating on the QCM-D gold–quartz crystal sensor surface is uniform and compact with a thickness of 35 nm and is tightly bonded to the sensor surface. The obtained HAP-coated sensor is thus suitable for QCM-D measurement.

Keywords

• calcium compounds
• quartz
• electrophoretic coating techniques
• scanning electron microscopy
• suspensions
• quartz crystal microbalances
• gold
• surface morphology
• nanostructured materials
• nanofabrication
• nanosensors
• electrophoretic coatings
• nanoindentation
• hydroxyapatite nanocoating
• gold–quartz crystal sensor
• quartz crystal microbalance
• dissipation measurement
• electrophoretic deposition technique
• nanoindention testing
• suspension concentration/electric-field strength
• sensor surface
• sensor coating
• electric-field strength
• coating compactness
• size 35.0 nm
• Au-SiO(2)
• Ca(10)(PO(4))(6)(OH)(2)