Ocean hdx vis nir

ZnS:Ag,Co@ZnS nanoparticles were mixed with PDMS to form a flat, cylindrical phantom (1.6 cm diameter × 0.2 cm thickness) with the nanoparticle concentration of 75 mg⋅mL⁻¹. The nanoparticles-containing PDMS sample was clamped and fixed by a custom holder with alligators and placed on top of a FUS transducer coupled with a degassed water bag (Image Guided Therapy) at room temperature, such that the FUS was focused inside and near the upper surface of the phantom. The center frequency of the transducer was 1.5 MHz, and the peak pressure at the focus was 1.86 MPa. A pulse train of 100 ms duration was delivered with a repetition frequency of 1 Hz. During the FUS application, a fiber-coupled spectrometer (OCEAN-HDX-VIS-NIR; Ocean Optics) was used to collect the emitted mechanoluminescence by placing the end of the optical fiber on the upper surface of the phantom opposite the FUS transducer. The spectral range of measurement was 400 to 650 nm, with a wavelength resolution of 0.366 nm and an acquisition time of 4 s.

Persistent luminescence spectra of bulk phosphors and colloidal nanophosphors were acquired using a fiber-coupled spectrometer (OCEAN-HDX-VIS-NIR; Ocean Optics, Orlando, FL) that measures the whole spectrum in the range of 350 to 900 nm spontaneously. A polydimethylsiloxane (PDMS) phantom containing a specific phosphor or nanophosphor colloid was used as the sample for spectral characterizations. Specifically, the PDMS phantom was charged by a 365-nm light-emitting diode (LED; SOLIS-365C, Thorlabs, Newton, NJ) at 5.7 mW/mm² for 10 s. The persistent luminescence spectrum was acquired immediately after the charging light was turned off. Averaging over multiple measurements was applied as needed to reduce the noise of the spectrum.

The luminescence quantum yield measurement was conducted by following protocols established in previous reports (14 (link), 33 (link), 50 (link)). Specifically, the SMSO nanophosphor colloid was excited by a collimated 365-nm light beam coupled from an LED (M365LP1, Thorlabs, Newton, NJ). An integrating sphere (IS200, Thorlabs, Newton, NJ) and a nonscanning fiber-coupled spectrometer (OCEAN-HDX-VIS-NIR; Ocean Optics, Orlando, FL) were used to redirect and collect the excitation and emission light simultaneously both during and after the recharging. The absorbed photons were measured by replacing the SMSO colloid with water and repeating the above procedure. The luminescence quantum yield was then calculated as follows $$\text{QY}=\frac{\text{Photons emitted}}{\text{Photons absorbed}}=\frac{{\displaystyle \underset{0}{\overset{t_{\text{Lum}}}{\int }}}{I}_{\text{Em}} \mathit{dt}}{(I_{\text{Ex}\_\text{ref}}-I_{\text{Ex}\_\text{SMSO}}) t_{\text{Ex}}}$$ where QY is the luminescence quantum yield; I_Em is the emission light intensity; I_{Ex_ref} and I_{Ex_SMSO} are the excitation light intensity in the presence of water or SMSO nanophosphor colloid, respectively; and t_Lum and t_Ex are the duration of luminescence and excitation light, respectively.