Dependence of optical scattering from Intralipid in gelatin-gel based tissue-mimicking phantoms on mixing temperature and time

Abstract

Abstract. Intralipid is widely used as an optical scattering agent in tissue-mimicking phantoms. Accurate control when using Intralipid is critical to match the optical diffusivity of phantoms to the prescribed value. Currently, most protocols of Intralipid-based hydrogel phantom fabrication focus on factors such as Intralipid brand and concentration. In this note, for the first time to our knowledge, we explore the dependence of the optical reduced scattering coefficient (at 532 nm optical wavelength) on the temperature and the time of mixing Intralipid with gelatin-water solution. The studied samples contained 1% Intralipid and were measured with oblique-incidence reflectometry. It was found that the reduced scattering coefficient increased when the Intralipid-gelatinwater mixture began to solidify at room temperature. For phantoms that had already solidified completely, the diffusivity was shown to be significantly influenced by the temperature and the duration of the mixing course. The dependence of the measured diffusivity on the mixing conditions was confirmed by experimental observations. Moreover, the mechanism behind the dependence behavior is discussed.

Laser Speckle Rheology for evaluating the viscoelastic properties of hydrogel scaffolds

“…3b along with the fitted curves, revealing distinct μ s ′ values of 0.9, 13.3, and 4.3 mm −1 respectively. Despite identical intralipid concentrations in all gels, differences in μ s ′ were likely due to variations in refractive index mismatch and curing protocols, as discussed later32.…”

“…3b, obtained from time-averaged speckle frames, revealed substantially different μ s ′ values caused by variations in curing processes and constituent materials. For instance, we speculate that the partially demulsified intralipid particles in heated agarose solutions floated and re-coalesced to increase the μ s ′ (4.3–17.5 mm −1 ) in these samples3241. We also observed that the polymerization of low molecular weights (M n  = 575) PEGDA increased the refractive index mismatch between the infused water and the emerging gel meshwork, creating a turbid hydrogel with increased μ s ′ (10.4–15.3 mm −1 )4243.…”

“…1). The intralipid emulsions have a well-established size distribution323449. Published reports using dynamic light scattering (DLS) and electron microscopy studies estimate a mean radius of a  ~ 100 nm for intralipid particles323450.…”

Optical focusing deep inside dynamic scattering media with near-infrared time-reversed ultrasonically encoded (TRUE) light

“…G2500-1kG, gel strength 300, Sigma-Aldrich, USA) and de-ionized water 51 with a lipid concentration of 1.5 g ml −1 . The reduced scattering coefficient μ S ’ was measured by a home-built oblique incidence reflectometer 52 to be 9.8 cm −1 .…”

Catheter-based photoacoustic endoscope

“…40 The gelatin was purchased from SigmaAldrich (#G2500-1kG; gel strength 300, Type A), and the Intralipid-gelatin-water phantom was made according to the recipe in Ref. 44. In this experiment, we utilized relatively large diameter targets compared with the previous tungsten wire imaging experiment to acquire PA signals with adequate signal-to-noise ratios; as the matrix medium is turbid, the optical fluence near the objects is much weaker than that in the clear medium.…”