Investigation of inkjet printing conditions for microdot pressure-sensitive sensor on anodized aluminum substrate

Abstract

A pressure-sensitive dot array sensor has been developed by means of an inkjet printing device on an anodized aluminum (AA) substrate. Pressure-Sensitive Paint formed on AA substrate (AA-PSP) has been used for unsteady pressure measurements due to its high-speed responsiveness. A bi-luminophore AA-PSP is demanded for precise pressure measurements, because PSP needs the temperature correction. However, a conventional bi-luminophore AA-PSP prepared by a dipping method does not work well due to the interference between the two luminophores. To overcome this problem, we have been developing the isolated dot arrays of PSP and TSP formed on an anodized aluminum substrate by an inkjet printing method. As the first step of realizing the combined AA-PSP・TSP, we fabricated a pressure-sensitive dot array sensor on an anodized aluminum substrate using Ru(dpp)3 as a pressure-sensitive luminophore. Ru(dpp)3 was dissolved in four different solvents: methanol, dichloromethane, chloroform and the mixed solvent of dichloromethane and chloroform, and the effect of the solvents on PSP dots was investigated. The formed PSP dots exhibited significantly different properties, such as the luminescence intensity distribution and pressure sensitivity, depending on the solvents. The PSP solution with methanol resulted in the O-shaped stain of luminophore due to the “coffee-ring effect”. The PSP solution with dichloromethane and that with the mixed solvent of dichloromethane and chloroform formed dots with uniform luminescence intensity distribution. In addition, the PSP with dichloromethane or dichloromethane + chloroform had comparable pressure sensitivity with conventional AA-PSP prepared by a dipping method, while the PSP with methanol showed very poor pressure sensitivity.

Keywords

• pressure-sensitive paint
• pressure measurement
• inkjet printing
• coffee-ring effect
• dot arrays