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Advanced Optical Technologies for Non-Invasive Sensing and Biomedical Monitoring

A Special Issue of Applied Sciences (ISSN 2076-3417) belonging to the section "Optics and Lasers".

Deadline for manuscript submissions: 1 June 2027 | Viewed by 822

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Guest Editor
Department of Electrical & Computer Engineering and Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
Interests: contactless physiological measurement systems; occupant monitoring and driver monitoring systems in vehicles; brain imaging for traumatic brain injury and monitoring patients; active illumination for remote sensing systems; super-continuum and other fiber laser technologies
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Special Issue Information

Dear Colleagues,

A broad range of optical devices serve as key enabling technologies for non-invasive sensing and biomedical monitoring; for example, one of the most common diagnostic tools used healthcare is the pulse oximeter, which uses photoplethysmography (PPG) to measure blood flow and derive heart rate and blood oxygen level data. With light sources such as light emitting diodes (LEDs) and vertical cavity surface emitting lasers (VCSELs) becoming commodity items with reduced cost and size and higher efficiency, more and more non-invasive sensing and biomedical monitoring techniques and devices are being deployed. For example, smart watches and rings use LED-based PPG devices to measure heart rate, pulse oximetry, and other physiological parameters. Moreover, camera-based system equipped with VCSEL active illuminators are being used for remote PPG (rPPG) or imaging PPG (iPPG), where contactless vital sign monitoring may be done at a distance. For wearables as well as contactless healthcare diagnostics, new techniques may be required to enable motion compensation, independence from ambient light, and measurements that are agnostic to skin color or tone.

This Special Issue seeks, therefore, contributions that describe advances in optical technologies for non-invasive sensing and biomedical monitoring. Optical techniques may be used to measure physiological parameters including heart rate, respiratory rate, blood oximetry and blood pressure. Additionally, contributions are sought that use machine learning and artificial intelligence processing to analyze the data for indications of ailments, such as atrial fibrillation or hypertension. The optical technologies may be incorporated into wearables such as smart watches or rings, tools that can be worn or placed in clothing, or even extended reality (XR) eyewear. Papers are also sought that explore the use of optical methodologies that can serve as wellness tools, and with proper regulatory approval, even in medical diagnostics. Finally, submissions that explore monitoring devices that advance personalized medicine with AI processing for anomalous occurrence detection are also welcome.

Prof. Dr. Mohammed N. Islam
Guest Editor

Manuscript Submission Information

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Keywords

  • contactless vital sign monitoring
  • non-invasive optical monitoring
  • physiological measurements
  • heart rate
  • respiratory rate
  • photoplethysmography (PPG)
  • remote PPG
  • imaging PPG
  • wearable optical sensors
  • machine learning and AI processing and sensor fusion of vital signs
  • contactless blood pressure or hypertension
  • oximetry
  • facial blood flow
  • chest motion
  • 3D cameras for vital signs
  • extended-reality eyewear for vital sign measurements

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Published Papers (1 paper)

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Research

15 pages, 30854 KB  
Article
Improvement of Bidirectional Schlieren Images Using Wavelet Transform for Optical Flow Application in Fluid Flows
by Jean M. González-Rangel, Carlos E. Hernández-Montañez, Montserrat G. Rivera-Ortiz, David Moreno-Hernández and Adrián Martínez-González
Appl. Sci. 2026, 16(11), 5631; https://doi.org/10.3390/app16115631 - 4 Jun 2026
Cited by 1 | Viewed by 409
Abstract
The Schlieren technique is a powerful tool used in its early years for flow visualization. However, over time, the optical system has been modified for measuring temperature and velocity fields in fluid flows. A tool utilized for measuring velocity fields in Schlieren images [...] Read more.
The Schlieren technique is a powerful tool used in its early years for flow visualization. However, over time, the optical system has been modified for measuring temperature and velocity fields in fluid flows. A tool utilized for measuring velocity fields in Schlieren images is the optical flow method. A requirement for successfully applying optical flow to Schlieren images is that the images contain sufficient contrast to satisfy the mathematical defining condition. On the other hand, a common Schlieren technique uses a single knife-edge cutoff to create contrast images, allowing refractive-index gradients to be imaged in only one direction. However, fluid movement occurs in both directions, leaving the flow information incomplete to study. In this work, we use a bidirectional Schlieren method to calculate velocity fields of a low-speed unstable fluid flow. The Schlieren images are processed using the continuous wavelet transform to enhance their contrast for optical flow applications. To generate the flow at low speed, we use a flapping plate at a fixed frequency. The results show that the continuous wavelet transform improves the image characteristics of Schlieren images for optical flow applications, and the bidirectional Schlieren method provides more information about the behavior of the unstable flow than the classical Schlieren system. On the other hand, to validate some experimental results, we compared them with a numerical simulation in ANSYS Fluent 2024r. The comparison results are in good agreement. Full article
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