Optical liquid phantom characterization

This dataset contains the results of the characterisation of liquid phantoms compounds and recipes that will be used to test hyperspectral systems.

We have characterize 4 compounds: Indian Ink, Protoporphyrin IX (PpIX), Blood (human and horse) and Yeast fluorescence.

The files contained here are:

• RawSpectraInk.zip: raw absorbance spectra of the Indian ink phantoms (Winsor & Newton, Black Indian 951) measured using a commercial spectrophotometer (PerkinElmer LAMBDA 950), between 400 and 900 nm with 0.5-nm resolution at 5 different concentrations (dilution in water) (0.2, 0.3, 0.4, 0.5 and 0.6 µl/ml).
• Spectrofluorometer_Yeast.zip. raw data of the fluorescence of baker’s yeast (Saccharomyces cerevisiae) diluted at a concentration of 20 mg/mL at different excitation wavelength measured using a commercial luminescence spectrometer (PerkinElmer LS 55). The illumination was sequential from 300 to 700 nm at 20-nm steps. Also contains the reference fluorescence spectra accounting from water and PS contribution without any yeast, illuminated from 300 to 400 nm at 20-nm steps
• SpectrophotometerSpectra.mat. Absorbance spectra of human blood, horse blood and PpIX.

The horse blood was defibrinated horse blood that can be easily purchased from a chemical supplier (https://uk.vwr.com/store/product/9131472/animal-blood-serum-products-for-microbiology) and the human blood was expired human red blood cells acquired from a blood bank.

The data here are the absorption spectra measured using a commercial spectrophotometer (PerkinElmer Lambda 750 S). For the blood, solution of 5% blood in PBS for both blood type was prepared . Then the blood samples where fully oxygenated by bubbling O2, and by monitoring the level of dissolved oxygen (DO2) in these solutions. Once fully oxygenated, the absorbance of the solution was measured in the spectrophotometer.  A second sample of deoxygenated blood was measured in the same conditions. In order to induce the deoxygenation of the solution, a small quantity of sodium dithionite was added to the oxygenated solution, and the measurement was taken after the DO2 meter reading had fallen to 0%.

The PpIX (solution of 1.2mM of PpIX in dimethyl sulfoxide (DMSO)) absorption spectra was measured with the same spectrophotometer.

Variables in the file:

Wavelength: the wavelength vector

Spectra: the absorbance spectra of each compound

Name: the name of each compound

The rest of the files report measurements performed in reflectance in a diffuse media. The setup used to test the different components was a metallic container, of dimensions 27 × 15 × 16 cm. The sides and bottom of the container were coated with a matt black absorbing paint to prevent any reflections from the boundaries. To ensure precise measurements of the volume, particularly for the large volumes of basal solution required, a gravimetric approach was used, as weighing liquids is a valid and accurate method for determining volume. DO2 levels within the solutions were monitored using a calibrated oxygen probe. Solution pH was concurrently monitored using a pH probe. The entire setup was placed on a hot stirring plate complete with a temperature probe, set to maintain a constant 37°C. Constant stirring at 700 RPM ensured that the solution remained homogeneous.

The optical setup was composed of a broadband light (HL-2000 UV-Vis-NIR Halogen Light Source by Ocean Optics) for the source and of a USB4000 spectrometer (Ocean Optics) for the detection. Light was guided from the light source and to the spectrometer via optical fibres with s source detector distance of 1 cm. The compositions of the baseline solution for the two phantoms is of 1400g of PBS solution (at 50mM) and 75g of Intralipid 20%.

The files contained here are:

• SpectraPpIXalone.mat. Attenuation spectra of the PpIX (at 15uM concentration) in the baseline solution described above.

Variables in the file:

Wavelength: the wavelength vector

Spectra: Attenuation spectra of the PpIX in the diffusive media

Name: the name of the spectra

• DeltaA_Human_Horse_Blood.mat: Change in attenuation between oxygenated and deoxygenated blood for both horse and human blood. 5 mL of blood were added to the baseline solution. The blood was deoxygenated using N₂.

Variables in the file:

Wavelength: the wavelength vector

Spectra: Change in attenuation between deoxygenated and oxygenated blood

Name: the name of the spectrum

• SpectraBloodPpIX.mat: Attenuation spectra of the blood with and without PpIX (same quantities as above) both for oxygenated and deoxygenated states.

Variables in the file:

Wavelength: the wavelength vector

Spectra: the attenuation spectra

Name: the name of the spectra