Mr. Greg Smith Profile

Greg Smith

at Gowerlabs Ltd

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Publications (7)

Proceedings Article | 9 December 2021 Paper

Evaluating a new generation of wearable high-density diffuse optical tomography (HD-DOT) technology via retinotopic mapping in the adult brain

Ernesto Vidal-Rosas, Hubin Zhao, Reuben Nixon-Hill, Greg Smith, Luke Dunne, Samuel Powell, Robert Cooper, Nicholas Everdell

Proceedings Volume 11920, 1192019 (2021) https://doi.org/10.1117/12.2615354

KEYWORDS: 3D modeling, Brain mapping, Visualization, Brain, Hemodynamics, Head, Diffuse optical tomography, Positron emission tomography, Functional magnetic resonance imaging, 3D image processing

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Proceedings Article | 9 December 2021 Paper

Towards cot-side mapping of the sensorimotor cortex in preterm and term infants with wearable high-density diffuse optical tomography

Elisabetta Maria Frijia, Hubin Zhao, Liam Collins-Jones, Greg Smith, Nicholas Everdell, Topun Austin, Robert Cooper

Proceedings Volume 11920, 119201C (2021) https://doi.org/10.1117/12.2615363

KEYWORDS: Sensors, Sensorimotor cortex, Diffuse optical tomography, Data modeling, Brain mapping, Brain, 3D acquisition, Video, Spatial resolution, Silicon

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Proceedings Article | 9 December 2021 Paper

ANIMATE: wearable, flexible, and ultra-lightweight high-density diffuse optical tomography technologies for functional neuroimaging of newborns

Hubin Zhao, Elisabetta Maria Frijia, Ernesto Vidal Rosas, Liam Collins-Jones, Greg Smith, Reuben Nixon-Hill, Samuel Powell, Nicholas Everdell, Robert Cooper

Proceedings Volume 11920, 119201A (2021) https://doi.org/10.1117/12.2615357

KEYWORDS: Neuroimaging, Diffuse optical tomography, Connectors, Sensors, Imaging arrays, Mechanical engineering, Light emitting diodes, Imaging systems, Absorbance, Traumatic brain injury

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SPIE Journal Paper | 9 April 2021 Open Access

Evaluating a new generation of wearable high-density diffuse optical tomography technology via retinotopic mapping of the adult visual cortex

Ernesto Vidal-Rosas, Hubin Zhao, Reuben Nixon-Hill, Greg Smith, Luke Dunne, Samuel Powell, Robert Cooper, Nicholas Everdell

NPh, Vol. 8, Issue 02, 025002, (April 2021) https://doi.org/10.1117/12.10.1117/1.NPh.8.2.025002

KEYWORDS: Diffuse optical tomography, Visualization, Neurophotonics, Visual cortex, Head, Brain, Hemodynamics, 3D modeling, Signal to noise ratio, Imaging systems

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SPIE Journal Paper | 26 March 2021 Open Access

Design and validation of a mechanically flexible and ultra-lightweight high-density diffuse optical tomography system for functional neuroimaging of newborns

Hubin Zhao, Elisabetta Frijia, Ernesto Vidal Rosas, Liam Collins-Jones, Greg Smith, Reuben Nixon-Hill, Samuel Powell, Nicholas Everdell, Robert Cooper

NPh, Vol. 8, Issue 01, 015011, (March 2021) https://doi.org/10.1117/12.10.1117/1.NPh.8.1.015011

KEYWORDS: Neuroimaging, Imaging systems, Connectors, Absorption, Sensors, Neurophotonics, Brain, Absorbance, Optical properties, Near infrared

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Significance: Neonates are a highly vulnerable population. The risk of brain injury is greater during the first days and weeks after birth than at any other time of life. Functional neuroimaging that can be performed longitudinally and at the cot-side has the potential to improve our understanding of the evolution of multiple forms of neurological injury over the perinatal period. However, existing technologies make it very difficult to perform repeated and/or long-duration functional neuroimaging experiments at the cot-side. Aim: We aimed to create a modular, high-density diffuse optical tomography (HD-DOT) technology specifically for neonatal applications that is ultra-lightweight, low profile and provides high mechanical flexibility. We then sought to validate this technology using an anatomically accurate dynamic phantom. Approach: An advanced 10-layer rigid-flexible printed circuit board technology was adopted as the basis for the DOT modules, which allows for a compact module design that also provides the flexibility needed to conform to the curved infant scalp. Two module layouts were implemented: dual-hexagon and triple-hexagon. Using in-built board-to-board connectors, the system can be configured to provide a vast range of possible layouts. Using epoxy resin, thermochromic dyes, and MRI-derived 3D-printed moulds, we constructed an electrically switchable, anatomically accurate dynamic phantom. This phantom was used to quantify the imaging performance of our flexible, modular HD-DOT system. Results: Using one particular module configuration designed to cover the infant sensorimotor system, the device provided 36 source and 48 detector positions, and over 700 viable DOT channels per wavelength, ranging from 10 to ∼45 mm over an area of approximately 60 cm2. The total weight of this system is only 70 g. The signal changes from the dynamic phantom, while slow, closely simulated real hemodynamic response functions. Using difference images obtained from the phantom, the measured 3D localization error provided by the system at the depth of the cortex was in the of range 3 to 6 mm, and the lateral image resolution at the depth of the neonatal cortex is estimated to be as good as 10 to 12 mm. Conclusions: The HD-DOT system described is ultra-low weight, low profile, can conform to the infant scalp, and provides excellent imaging performance. It is expected that this device will make functional neuroimaging of the neonatal brain at the cot-side significantly more practical and effective.

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