Pressure sensitive paint (PSP) has widely used in many engineering field, both in a micro scale and in a macro scale, due to the rapid development of hardware. That is also supported by many fundamental researches of researchers in various fields. The temporal spatial resolution of the PSP and the reliability became higher. The PSP can be also applied to the unsteady flow field and to relatively low speed flow with less pressure change. In the report, the state of the art of the PSP is summarizes from a broad point of view, including following topics, sensor materials for the pressure and temperature measurements, hardware, the intensity-based measurement method, the lifetime-based technique, simultaneous measurements, combined measurements, practical applications and so on.

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  Two types of the pressure-sensitive paint measurement techniques for high-speed wind tunnels, which include transonic and supersonic ones, were introduced. They were the practical PSP measurement, whose targets were development tests of aerospace vehicles, and the unsteady PSP measurement.　
For the practical PSP measurement, PSP/TSP paints, measurement systems, and data reduction methods were described. Then, the global PSP measurement results of the DLR-F6 model were discussed about pressure distribution and variation between those of two AoA cases.　
For the unsteady PSP measurement, PSP paint/coating of anodized-aluminum PSP and silica nanoparticle PSP and measurement system were described, then, the unsteady PSP measurement results of the rocket faring model using AA-PSP and those of the delta wing model using silica nanoparticle PSP, whose targets were transonic buffet phenomena, were introduced.

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  Pressure sensitive paint (PSP) is an optical technique to measure surface pressure. PSP is now widely used in various wind-tunnel tests, however application to low-speed flow is still one of the most difficult challenges for PSP. Pressure change in low-speed test is quite small, although PSP measurement has various error sources. It is important to understand key-point of low-speed PSP application and minimize the measurement errors. In this study, recent development of PSP techniques for low-speed tests, both steady and unsteady pressure measurement, are discussed.

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  Motion-capturing pressure-sensitive paint (PSP) method is a PSP measurement method that can be applied to capture the surface pressure information on a moving object. It uses two-luminescent outputs from a two-color PSP. One output is independent of the pressure and the other is dependent on the pressure. These provide separate luminescent peaks, which are simultaneously captured by a high-speed color camera. Further description of this method is included in this paper. Some of the unsteady fluid-dynamic measurements by using this method are included in this paper. These include the applications in airfoil flutter and a ballistic range.

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  This paper presents a novel combined PSP・TSP sensor, which is composed of arrays of tiny PSP and TSP dots. We fabricated the combined sensor, dual-array sensor, by inkjet-printing of PSP and TSP solutions. The dual-array sensor is unique among combined PSP・TSP sensors in the point that PSP and TSP luminophores are discretely arranged on a measurement surface. This prevents interactions between PSP and TSP luminophores that has been one of major issues in conventional combined sensors, and makes it possible to select optimal binding material and solvent for each luminophore. From emission spectrum, pressure and temperature sensitivities of a fabricated dual-array sensor, the dual-array sensor is able to combine any luminophores without paying attention to the interaction issues. Moreover, a demonstration shows that the dual-array sensor is a favorable pressure sensor for the measurements on surfaces with non-uniform temperature distribution.

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