Addition of Silica-Coated Ag Nanoparticles to Enhance Luminescence Intensity of Pressure-Sensitive Paints

Abstract

Enhancement of the luminescent output of pressure-sensitive paint (PSP) has been achieved by adding silver nanostructures into a standard formulation by taking advantage of a metal-enhanced fluorescence effect. Traditionally, metal-enhanced fluorescence has been used in microscopy or thin-film sensing. However, in PSP applications, the luminescent film is applied onto large surfaces by using conventional paint application techniques, and imaging is acquired from longer distances. As such, many of the techniques deployed for maximum enhancement (such as careful spacing of the metal centers) is not easily achievable. Initial trials consisted of adding silver nanostructures into a PSP formulation. The luminescent enhancement was highly dependent on the concentration of the oxygen-sensitive dye. At very low concentrations of the dye (<10 μM), enhancements more than a factor of 3 could be achieved. However, as the concentration of the dye increased (∼800 μM), the enhancement effect reduced and eventually diminished the signal. This was due to the dark color of the silver and the decrease in the distance between the dye and the silver nanostructures, leading to quenching of luminescence. To alleviate this problem, silver nanoparticles were coated with a silica shell, which acted as a spacer keeping the dye and silver nanoparticles at a suitable distance from each other to maximize the luminescence enhancement without quenching being observed regardless of the nanoparticle concentration. This resulted in an enhancement factor of more than 1.5. Excited-state lifetime measurements were also acquired to verify that the enhancement was due to metal-enhanced fluorescence.

Multifunctional optical sensing platform of temperature, pressure (vacuum) and laser power density: NaYF4: Gd3+, Yb3+, Er3+ nanomaterial as luminescent thermometer, manometer and power meter

“…[2][3][4][5]7,41 On the other hand, lowpressure luminescent sensors (operating below 1 bar) utilize the loss of concentration of gas molecules, which directly affects the local temperature rise or the quenching of luminescence (emission intensity variations), this discovery enables the design of vacuum sensors using the luminescent thermometers/heaters, this view is based on the effect of laser heating of materials, which is enhanced in vacuum conditions. 10,11,33,34 In this work, we show that NaYF 4 : Gd 3+ , Yb 3+ , Er 3+ , nanomaterial can be used as a multifunctional detector for temperature and pressure using the vacuum-enhanced light-to-heat conversion (see Fig. 1(a)).…”

Polymerizable Oxygen Probe Derived from Platinum-Based Porphyrins for Oxygen Sensing and Pressure-Sensitive Paints

“…The pressure-dependent intensity ratio ( I ref / I ) curves of F1a , F2 , and F3 are plotted in Figure B according to the pressure-sensitive Stern–Volmer equation (eq ). , Both F1a , F2 , and F3 can respond to pressure linearly at different pressures. where I is the emission intensity at different pressures; I ref is the emission intensity at 100 kPa; A 0 and A 1 are the Stern–Volmer constants at a certain temperature; and P is the pressure ranging from 50 to 150 kPa. Pressure sensitivities ( S P s) of F1a , F2 , and F3 were calculated using eq . , where I ref and I are the emission intensities at the reference pressure and different pressures; A 1 is the Stern–Volmer constant; and P is the reference pressure of 100 kPa.…”

“…Polymers containing oxygen probes are usually used as PSP. Oxygen probes such as metalloporphyrin, ruthenium­(II) polypyridyl complexes, and pyrene derivatives are usually physically doped into polymer matrices to obtain PSPs. − This preparation method is simple and convenient. However, the solubility of oxygen probes in polymer matrices is low, and the oxygen probes are easy to aggregate in polymer matrices to result in nonlinear Stern–Volmer responsive curves to pressure or low sensitivity. , To alleviate this problem, polymers with chemically conjugated oxygen probes were investigated.…”

Synthesis of fluorinated copolymers and their applications as pressure‐responsive materials

“…[19][20][21] There are three main methods for preparing PSPs. 22 The most widely used one is the physical doping method that mixes oxygen probe molecules into polymer materials, [23][24][25] because of its simplicity and convenience. However, the solubility of oxygen probes in polymer matrices normally is low, and the oxygen probes are easy to aggregate in polymer matrices, resulting in their low sensitivity.…”