Dr. Amanda Cheung Profile

Dr. Amanda Cheung

PhD Student at The Univ of British Columbia

SPIE Involvement:

Author

Publications (7)

SPIE Journal Paper | 25 July 2022 Open Access

Detection of hypoxia by near-infrared spectroscopy and pulse oximetry: a comparative study

Amanda Cheung, Lorna Tu, Andrew Macnab, Brian Kwon, Babak Shadgan

JBO, Vol. 27, Issue 07, 077001, (July 2022) https://doi.org/10.1117/12.10.1117/1.JBO.27.7.077001

KEYWORDS: Near infrared spectroscopy, Hypoxia, Oximetry, Oxygen, Oximeters, Sensors, Tissue optics, Tissues, Ear, Blood

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Proceedings Article | 2 March 2022 Presentation + Paper

A method for the fixation of an implantable spinal cord NIRS sensor

Amanda Cheung, Shahbaz Askari, Farnaz Sahragard, Katharina Raschdorf, Megan Webster, Audrey Warner, Jay Ethridge, Kitty So, Garret Frank, Julia Hill, Femke Streijger, Brian Kwon, Babak Shadgan

Proceedings Volume 11956, 1195606 (2022) https://doi.org/10.1117/12.2609065

KEYWORDS: Sensors, Near infrared spectroscopy, Spinal cord, Silicon, Fluoroscopy, Surgery, Photodetectors, Injuries, Light emitting diodes

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Proceedings Article | 2 March 2022 Presentation + Paper

Histological assessment of an implantable optical sensor and spinal cord tissue interface

Farnaz Sahragard, Amanda Cheung, Femke Streijger, Shahbaz Askari, Brian Kwon, Babak Shadgan

Proceedings Volume 11956, 1195607 (2022) https://doi.org/10.1117/12.2614081

KEYWORDS: Sensors, Spinal cord, Near infrared spectroscopy, Tissue optics, Injuries, Tissues, Photodetectors, Optical sensors, Light emitting diodes, Silicon

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Background: We developed an implantable optical sensor based on near-infrared spectroscopy (NIRS) to continuously monitor spinal cord oxygenation and hemodynamics in patients with acute spinal cord injury (SCI). As a safety assessment measure, we aimed to study the effect of near-infrared (NIR) light emission and contact compression of the NIRS sensor on spinal cord tissue structure. Our previous in-vitro heat tests indicated no heat generation by the NIRS sensor. This study evaluated whether the NIRS sensor resulted in any potential compression damage to the spinal cord using histological analysis. Methods: Six Yucatan mini-pigs received a T10 SCI. A custom implantable NIRS sensor (version 2) was placed extradurally on the spinal cord and fixed with magnets and cross-connectors. After seven days of continuous data collection at 100Hz, the sensor was removed to allow for histological examination of the spinal cord tissue. Cellular damage was observed in the spinal cord at the NIRS sensor placement site in two animals. The design, shape, and material of the NIRS sensor were significantly revised to reduce the sensor footprint, minimize the compression on the cord, increase the sensor flexibility, and improve its clinical application. An in-vivo pilot experiment was performed on a Yucatan miniature pig with a T10 SCI to evaluate potential compression damage of the spinal cord tissue from placement and direct contact of the refined NIRS sensor (version 5). A fibrin sealant, TISSEEL, was utilized to fix the version 5 NIRS sensor on the spinal cord. Result: There were no signs of cellular damage, indentation, and significant flattening on the dorsal surface of the spinal cord where the version 5 NIRS sensor was placed for up to 4.5 hours. Conclusion: The refined NIRS sensor did not cause any compression damage to the porcine spinal cord after implantation for 4.5 hours. Implanting this sensor on the spinal cord of SCI patients requires further in-vivo examinations to ensure the sensor is safe to use for up to 14 days.

Proceedings Article | 8 March 2021 Presentation + Paper

Testing the safety of a custom NIRS sensor designed to monitor spinal cord hemodynamics

Farnaz Sahragard, Amanda Cheung, Femke Streijger, Brian Kwon, Babak Shadgan

Proceedings Volume 11651, 116510L (2021) https://doi.org/10.1117/12.2585329

KEYWORDS: Sensors, Near infrared spectroscopy, Spinal cord, Safety, Hemodynamics, Tissues, Temperature metrology, In vitro testing, Injuries

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Background: A customized sensor, based on near-infrared spectroscopy (NIRS), was developed to non-invasively monitor spinal cord hemodynamics after acute spinal cord injury (SCI). However, the effect of direct contact and emission of the NIRS signals on the spinal cord tissue structure was not clear. This information is essential because even minimal heating or contact pressure from the NIRS sensor placed over the injured spinal cord may lead to further damage to the spinal cord tissue. Here, we evaluate the safety of the custom-made NIRS sensor as it is essential prior to its clinical translation. Methods: A custom-made multi-wavelength miniaturized NIRS sensor was placed extradurally on the spinal cord of six Yucatan mini-pigs who received a T10 SCI. After seven days of continuous data collection at 100 Hz, the sensor was removed and the spinal cord tissue was examined. Histological assessment of the spinal cord revealed evidence of cellular damage at the NIRS sensor placement in two animals. An in-vitro experiment was performed to evaluate the possibility of heat damage caused by the NIRS sensor. Using a digital thermometer with two probes, one directly touching the NIRS emitter and the other one at a control site one centimeter away from the emitter. The amount of heat generation of the NIRS emitter after seven days of continuous operation at 100 Hz was measured and compared with the control site. Results: In-vitro heat tests showed no heat generation by the NIRS sensor. The temperature measured from the emitter site of the NIRS sensor and control temperature probe was identical during the seven days. Conclusion: The custom-made NIRS sensor does not generate heat at the emitter site and physical damage observed with regards to histology is due to the compression applied from the sensor. By refining the sensor to be smaller and more flexible with an even surface, we will improve the safety of the NIRS sensor before translating this technology to human patients. The new sensor will be further examined.