Dr. Walter Messina Profile

Dr. Walter Messina

at Tyndall National Institute

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Publications (6)

Proceedings Article | 13 March 2024 Poster

Development of an implantable platform for long-term bio-sensing in the context of pain management

Kiang Wei Kho, Gavin Byrne, Sanathana Konugolu, Jean de Souza Matias, Walter Messina, Michelle Roche, David Finn, Brian McQuire, Simon Riou, Stefan Andersoon-Engels

Proceedings Volume PC12850, PC128500J (2024) https://doi.org/10.1117/12.3002727

KEYWORDS: Biosensing, Near infrared, Nanosensors, Hydrogels, Upconversion, Power consumption, Nanoparticles, Light sources and illumination

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Proceedings Article | 28 February 2024 Paper

Spectral feature exploration for lactate sensing using long wavelength near infrared spectroscopy lactate sensing for non-invasive continuous hypoxia assessment in intra-partum fetus

Shree Krishnamoorthy, Huihui Lu, Walter Messina, Fergus McCarthy, Stefan Andersson-Engels, Ray Burke

Proceedings Volume 12628, 126280C (2024) https://doi.org/10.1117/12.2669908

KEYWORDS: Hypoxia, Fetus, Near infrared spectroscopy, Urea, Traumatic brain injury, Spectroscopy, Reflectivity, Oxygen, Liquids, Gold

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Proceedings Article | 11 August 2023 Paper

Towards a flexible polarimetric camera-on-tip miniature endoscope for 3x3 Mueller matrix measurements of biological tissue

Lorenzo Niemitz, Simon Sorensen, Yineng Wang, Walter Messina, Ray Burke, Stefan Andersson-Engels

Proceedings Volume 12627, 1262733 (2023) https://doi.org/10.1117/12.2670607

KEYWORDS: Cameras, Polarizers, Polarimetry, Light sources and illumination, Mueller matrices, Endoscopes, Polarization, Tissues, Design and modelling, Imaging systems

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The interrogation of polarisation state of light is a developing technique in biomedical imaging. As polarised light interacts with structural changes in tissue, it has seen use in differentiation between (pre)cancerous and noncancerous tissue, for example. In biomedical imaging rapid diagnostics using minimally invasive techniques is desirable. Endoscopy is already very prevalent in medicine and therefore miniaturisation of polarimetry systems onto endoscopic platforms is a natural development. Flexibility of such a device allows navigation to more complicated parts of the body. All polarimetric systems consist of a polarisation state generator (PSG) and a polarisation state analyser (PSA) which need to be integrated into such a system. A rigid endoscope capable of imaging a full 4×4 Mueller matrix has been developed by Qi et al. This endoscope achieves the polarisation state generation a rigid rotating sheath. Partial polarimetric endoscopy which captures a 3×3 Mueller matrix has also been demonstrated and is easier to achieve since it does not require quarter wave plates in the generator or analyser. Clancy et al and Qi et al both demonstrate a rigid polarimetric endoscopy using a stereo endoscope and a standard rigid endoscopy, respectively. Integration of polarisation state analyser and generator into the tip has been demonstrated using complex mechanical designs. However questions have been raised regarding the electromagnetic compatibility of such a system due to the presence of motors in the tip. Forward et al present a flexible 3×3 fibre based probe that uses diced polarisers orientated at the horizontal, vertical, and -45 degree positions to generate and acquire the necessary polarisation states. This work presents an imaging probe designed to enable in-vivo polarimetry measurements using a micro camera on the tip as a sensor. A 3×3 Mueller matrix image of crossed linear polarisers, captured using a micro camera is demonstrated. This device demonstrates the potential of micro camera sensors in providing 2-dimensional polarimetry data in a flexible endoscopic system. For a device to be used in a clinical setting it needs to be capable of providing data rapidly when it is needed, as well as being navigable to the target location. A fibre optically illuminated endoscope with micro-camera sensor allows for rapid switching of illumination fibres using backend illumination systems as well as rapid acquisition of data. Optical fibres enable the probe to be rigid or flexible depending on application, and the camera at the tip ensures consistent image quality regardless of application area. An idealised system and its potential future of polarimetry in translational biophotonic devices is also discussed.

Proceedings Article | 8 March 2023 Presentation + Paper

Non-invasive continuous hypoxia assessment in intra-partum fetus through long wavelength near infrared spectroscopy

Shree Krishnamoorthy, Urbashi Basu, Kiangwei Kho, Rekha Gautam, Francesca Di Croce, Walter Messina, Cleitus Antony, Paul Townsend, Fergus McCarthy, Stefan Andersson-Engels, Ray Burke

Proceedings Volume 12428, 124280M (2023) https://doi.org/10.1117/12.2648375

KEYWORDS: Short wave infrared radiation, Hypoxia, Fetus, Near infrared spectroscopy, Spectroscopy, Monte Carlo methods, Reflectivity, Sensors, Reflectance spectroscopy, Photon transport, Near infrared

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Proceedings Article | 6 March 2023 Presentation + Paper

Time resolved SPAD micro-camera probe for wide-field FLIm in microendoscopy

Dario Angelone, Sanathana Konugolu Venkata Sekar, Walter Messina, Andrew Matheson, Ahmet Erdogan, Robert Henderson, Ray Burke, Stefan Andersson-Engels

Proceedings Volume 12368, 1236807 (2023) https://doi.org/10.1117/12.2648340

KEYWORDS: Single photon avalanche diodes, Biological samples, In vivo imaging, Fluorescence intensity, Fluorescence, Spatial resolution, Miniaturization, Semiconductor lasers, Microscopes, Integrated optics

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SPIE Journal Paper | 1 November 2021 Open Access

Lung tissue phantom mimicking pulmonary optical properties, relative humidity, and temperature: a tool to analyze the changes in oxygen gas absorption for different inflated volumes

Andrea Pacheco, Konstantin Grygoryev, Walter Messina, Stefan Andersson-Engels

JBO, Vol. 27, Issue 07, 074707, (November 2021) https://doi.org/10.1117/12.10.1117/1.JBO.27.7.074707

KEYWORDS: Capillaries, Lung, Absorption, Optical properties, Tissue optics, Liquids, Humidity, Sensors, Data acquisition, Tissues

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Significance: Gas in scattering media absorption spectroscopy (GASMAS) enables noninvasive gas sensing in the body. It is developing as a tool for diagnosis and monitoring of respiratory conditions in neonates. Phantom models with relevant features to the clinical translation of GASMAS technology are necessary to understand technical challenges and potential applications of this technique. State-of-the-art phantoms designed for this purpose have focused on the optical properties and anthropomorphic geometry of the thorax, contributing to the source–detector placement, design, and optimization. Lung phantom mimicking the alveolar anatomy has not been included in the existent models due to the inherent complexity of the tissue. We present a simplified model that recreates inflated alveoli embedded in lung phantom. Aim: The goal of this study was to build a lung model with air-filled structures mimicking inflated alveoli surrounded by optical phantom with accurate optical properties (μa = 0.50 cm − 1 and μs′=5.4 cm−1) and physiological parameters [37°C and 100% relative humidity (RH)], and to control the air volume within the phantom to demonstrate the feasibility of GASMAS in sensing changes in pulmonary air volume. Approach: The lung model was built using a capillary structure with analogous size to alveolar units. Part of the capillaries were filled with liquid lung optical phantom to recreate scattering and absorption, whereas empty capillaries mimicked air filled alveoli. The capillary array was placed inside a custom-made chamber that maintained pulmonary temperature and RH. The geometry of the chamber permitted the placement of the laser head and detector of a GASMAS bench top system (MicroLab Dual O2 / H2O), to test the changes in volume of the lung model in transmittance geometry. Results: The lung tissue model with air volume range from 6.89 × 10 − 7 m3 to 1.80 × 10 − 3 m3 was built. Two measurement sets, with 10 different capillary configurations each, were arranged to increase or decrease progressively (in steps of 3.93 × 10 − 8 m3) the air volume in the lung model. The respective GASMAS data acquisition was performed for both data sets. The maximum absorption signal was obtained for configurations with the highest number of air-filled capillaries and decreased progressively when the air spaces were replaced by capillaries filled with liquid optical phantom. Further studies are necessary to define the minimum and maximum volume of air that can be measured with GASMAS-based devices for different source–detector geometries. Conclusions: The optical properties and the structure of tissue from the respiratory zone have been modeled using a simplified capillary array immersed in a controlled environment chamber at pulmonary temperature and RH. The feasibility of measuring volume changes with GASMAS technique has been proven, stating a new possible application of GASMAS technology in respiratory treatment and diagnostics.

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