arXiv subjects

Gannon Lemaster

Publications and source records attributed to Gannon Lemaster.

2 recordsLinked to original sources

arXiv2026

Ultrafast light-sheet optical tweezers for in situ parallelized biomechanical characterization of cells and soft tissues

Quantitative characterization of the mechanical properties of cells and tissues is essential for understanding disease progression and tissue regeneration. Optical tweezers (OT) enable the direct application of biologically relevant forces; however, OT has been limited to single axial indentations of cells, thereby restricting throughput. Furthermore, the use of quadrant photodiodes is insufficient for assessing the large displacements required for biomechanical characterization of tissues. We present light-sheet optical tweezers as a force transducer (LOFT), an approach that improves the throughput by at least 3x through simultaneous multiparticle trapping and parallelized characterization under sub-nN forces. LOFT is achieved by uniquely integrating light-sheet illumination for extended trapping, femtosecond-pulsed lasers to augment the optical gradient force, and videography-based particle tracking for observation of force transduction. The platform is validated through single-cell indentation experiments. We then apply LOFT to myocardial tissue, revealing significant biomechanical differences between healthy and infarcted regions; the interpretation of which is further supported by quantitative multiphoton imaging using the same optical source and platform. This work represents the first demonstration of OT for the mechanical testing of intact soft tissues, and establishes LOFT as a versatile, multifunctional platform for high-throughput, minimally invasive, mechanical characterization of complex biological systems in situ.

physics.optics↗

arXiv2024

Smartphone tristimulus colorimetry for skin-tone analysis at common pulse oximetry anatomical sites

Significance: Smartphones hold great potential in point-of-care settings due to their accessibility and computational capabilities. This is critical as clinicians increasingly seek to quantify skin-tone, a characteristic which has been shown to impact the accuracy of pulse oximetry readings, particularly for dark skin tones, and hence, disproportionately affect patient outcomes. Aim: This study presents a smartphone-based imaging technique for determining individual typology angle (ITA) and compares these results to those obtained using an industry-standard tristimulus colorimeter, particularly for the finger, a common site for pulse oximetry measurements. Approach: We employ a smartphone-based imaging method to extract ITA values from four volunteers with diverse skin-tones. The study provides recommendations for minimizing errors caused by ambient light scattering, which can affect skin-tone readings. Results: The smartphone-based ITA (SITA) measurements with camera flash disabled and minimal ambient lighting correlates well with the industry-standard colorimeter without the need for auxiliary adapters and complex calibration. The method presented enables wide-field ITA mapping for skin-tone quantification that is accessible to clinicians. Conclusions: Our findings demonstrate that smartphone-based imaging provides an effective alternative for assessing skin-tone in clinical settings. The reduced complexity of the approach presented makes it highly accessible to the clinical community and others interested in carrying out pulse oximetry across a diversity of skin-tones in a manner that standardizes skin-tone assessment.

physics.med-ph↗