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A special issue of Photonics (ISSN 2304-6732). This special issue belongs to the section "Biophotonics and Biomedical Optics".

Deadline for manuscript submissions: closed (15 September 2024) | Viewed by 16426

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Special Issue Editors

Dr. Chen Bai

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Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China
Interests: optical microscopy; computational imaging; biophotonics; deep learning; compressive sensing
Special Issues, Collections and Topics in MDPI journals

Dr. Yuecheng Shen

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Guest Editor

School of Electrical and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
Interests: optical imaging; wavefront shaping; imaging/focusing through scattering media
Special Issues, Collections and Topics in MDPI journals

Dr. Yichen Ding

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Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX 75080, USA
Interests: optical microscopy; tomography; image post-processing; machine learning; interactive visualization

Dr. Haixia Wang

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Guest Editor

The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou 510630, China
Interests: nano–bio interface; protein corona; bioimaging; nanoprobe; drug delivery

Special Issue Information

Dear Colleagues,

Optical microscopy has brought revolutionary progress to life science and medical research. In recent years, bio-photonics has emerged and become an interdisciplinary subject which utilizes the principles and technologies of photonics to explore life sciences. One of the development priorities of bio-photonics is to apply various optical systems and technologies for recognition and multimodal imaging at high temporal and spatial resolution. By utilizing these techniques, the structures and functions of biological tissues can be visualized to achieve disease diagnosis at macro–micro scales. With the rapid development of optoelectronic technologies, computational imaging and artificial intelligence, the performance of bio-photonics and related multimodal imaging has been progressing significantly, providing a powerful tool for clinical and biomedical research. Therefore, advanced bio-photonic technology has a very important application prospect in the fields of life science exploration, clinical diagnosis, and functional imaging. In order to focus on the latest research progress in optical microscopy and multimodal imaging technology, and to promote interdisciplinary integration and the development of bio-photonics, we welcome original research articles and reviews for submission to this Special Issue. Research areas may include (but are not limited to) the following:

Quantitative phase imaging
Three-dimensional imaging
Super resolution imaging
Optical focusing and imaging within or through scatters
Multi-photon imaging
Multi-mode and multi-functional imaging
Artificial intelligence and deep learning for bio-photonics
Compressed ultrafast microscopy
Spatial light modulation and PSF engineering for microscopy
Polarization of light in biomedical applications
Light-field microscopy
Hyperspectral imaging
Photoacoustic tomography

We look forward to receiving your contributions.

Dr. Chen Bai
Dr. Yuecheng Shen
Dr. Yichen Ding
Dr. Haixia Wang
Guest Editors

Manuscript Submission Information

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Keywords

digital holography
light-sheet microscopy
structured illumination microscopy
two/multi-photon microscopy
fluorescence microscopy
computational imaging
spatial light modulation
polarization imaging
photoacoustic tomography

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Published Papers (12 papers)

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Research

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19 pages, 3105 KiB

Open AccessArticle

Predictive Model of the Effects of Skin Phototype and Body Mass Index on Photobiomodulation Therapy for Orofacial Disorders

by Alice Cassemiro, Lara Jansiski Motta, Paulo Fiadeiro and Elsa Fonseca

Photonics 2024, 11(11), 1038; https://doi.org/10.3390/photonics11111038 - 5 Nov 2024

Viewed by 463

Abstract

Monte Carlo techniques have been extensively used for planning laser-based clinical procedures such as photobiomodulation. However, the effects of several biological tissue characteristics regarding its morphological structure and physiological parameters have not been carefully addressed in many applications. Specifically, many questions remain concerning the effect of skin phototype and body mass index on the effectiveness of photobiomodulation for extraoral therapies. To address these questions, a Monte Carlo simulation model of the effects of body mass index-dependent skin structure on different Fitzpatrick skin types was developed, specifically tailored for the morphological characteristics of cheek tissue. The model describes the settings of a typical oral photobiomodulation treatment protocol for pain relief, namely the use of 660 nm and 808 nm laser wavelengths and a therapeutic dose of

2.0 {J / cm}^{2}

on the masseter muscle. The simulations were used to train a machine learning predictive model aimed at accelerating the treatment planning stage and assessing the importance of patient-specific parameters. A multiple-regression approach was adopted to predict muscle dose and treatment time for effective delivered dose. Body mass index had little effect on epidermal energy deposition, but an important impact on muscle dose parameters. Phototype also influenced muscle dose, but to a lesser extent than body mass index. The results of this study can be used to develop customized dosimetry phototherapy protocols to promote more effective and safe clinical outcomes. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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9 pages, 2469 KiB

Open AccessArticle

Thermoacoustic Imaging Using Single-Channel Data Acquisition System for Non-Invasive Assessment of Liver Microwave Ablation: A Feasibility Study

by Ling Song, Wanting Peng, Qiang Lu, Lian Feng, Zeqi Yang, Lin Huang and Yan Luo

Photonics 2024, 11(9), 807; https://doi.org/10.3390/photonics11090807 - 29 Aug 2024

Viewed by 836

Abstract

Microwave ablation (MWA) plays a crucial role in non-surgical liver cancer treatment, but the existing efficacy evaluation tools lack the characteristics of being real-time, non-invasive, and efficient. As an emerging imaging technology, thermoacoustic imaging (TAI) has attracted extensive clinical attention for its excellent merits, which combine the advantages of high contrast in microwave imaging and high resolution in ultrasound imaging. Particularly, the application of a circular scanned single-channel data acquisition system maximizes the capture of thermoacoustic signals, thereby providing more comprehensive image information and rendering reconstructed images closer to reality. This study aimed to verify the feasibility of TAI in non-invasive evaluation of the efficacy of MWA on ex vivo porcine liver and in vivo rabbit liver. During the experiments, ultrasound is used to cross-verify the results of TAI to ensure the accuracy and reliability of the method. Additionally, by altering the thickness of porcine liver tissue to increase the distance (from 0 mm to 80 mm) between the horn antenna and the target (soy sauce tube), TAI is used to observe the change of the image signal-to-noise ratio to preliminarily explore the imaging depth of TAI. The results of ex and in vivo experiments can not only promote the clinical application of TAI, but also be expected to provide a more accurate and reliable efficacy assessment method for MWA in liver cancer treatment. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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10 pages, 1635 KiB

Open AccessArticle

Effect of Small Angle Misalignments on Ocular Wavefront Zernike Coefficients

by Ebrahim Safarian Baloujeh, Francisco J. Ávila and José M. González-Méijome

Photonics 2024, 11(9), 795; https://doi.org/10.3390/photonics11090795 - 27 Aug 2024

Viewed by 585

Abstract

Purpose: To assess the possible impact of minor changes in fixation on wavefront measurements as a potential constraint in detecting subtle temporal variations in ocular wavefront error. Methods: Twelve healthy subjects with an average age of 36.3 ± 8.8 were instructed to put their heads in the aberrometer’s chin-rest and look at a fixation target that was embedded in the device. The fixation targets were readily observable to the participants without accommodation, thanks to the aberrometer’s Badal system. When each eye was staring at the target, its wavefront aberration was recorded three times and then averaged for further analysis. The averaged Zernike coefficients were rescaled to the smallest value of the maximum round pupil found among all eyes (4.41 mm), and this procedure was repeated for each target. Results: Alteration of the fixation targets caused changes to the Zernike coefficients of defocus (C(2,0)), vertical trefoil (C(3,–3)), vertical coma (C(3,–1)), horizontal coma (C(3,1)), oblique trefoil (C(3,3)), primary spherical aberration (C(4,0)), and secondary spherical aberration (C(6,0)), but the changes were not statistically significant. Nevertheless, an alteration in the target’s size and shape exhibited a significant correlation across all of the aforementioned coefficients in both eyes (p < 0.05). The total RMS of aberrations and the RMS of the spherical-like aberrations were both lowest while choosing the larger Maltese cross, and the bigger E-letter minimized the RMS of HOA and comatic aberrations. Conclusion: The aberrometric changes occur as a consequence of altering the fixational gaze and are within the range of the changes found after performing a near-vision task, so they might potentially act as a confounding factor when attempting to identify such small variations in the ocular wavefront. Using a smaller E-letter (5 arcmin) as an internal fixation target resulted in the least standard deviation of measurements, fixational stability, and higher accuracy in ocular wavefront measurements. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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16 pages, 2896 KiB

Open AccessArticle

On the Origin of the Photoplethysmography Signal: Modeling of Volumetric and Aggregation Effects

by Denis G. Lapitan, Andrey P. Tarasov, Maria E. Shtyflyuk and Dmitry A. Rogatkin

Photonics 2024, 11(7), 637; https://doi.org/10.3390/photonics11070637 - 3 Jul 2024

Viewed by 969

Abstract

This study aimed to examine the mechanisms of the photoplethysmography (PPG) signal formation using Monte Carlo simulations of light transport in biological tissues and experimental observations. Based on a three-layer skin model in backscattering geometry, we sequentially simulated volumetric blood changes and the aggregation/disaggregation of erythrocytes in the dermal layer and estimated their contribution to the registered PPG signal. The calculations were conducted for two wavelengths: 525 nm and 810 nm. For green light, absorption predominates over scattering in the formation of a PPG signal, whereas, for near-infrared light, scattering prevails over absorption. This theoretical result was verified using the Modified Beer–Lambert law and clinical in vivo PPG data of seven healthy subjects. Changes in the size of the scatterers during erythrocyte aggregation and disaggregation can significantly contribute to the PPG signal at near-infrared light. Thus, for the green waveband, the classical volumetric model can be considered dominant in the PPG signal formation. In contrast, for the near-infrared range, both volumetric and aggregation effects must be considered as being approximately equal. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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11 pages, 2687 KiB

Open AccessArticle

Optical Manipulation of Fibroblasts with Femtosecond Pulse and CW Laser

by Xia Zhang, Yi Wu, Siao Cai and Guoying Feng

Photonics 2024, 11(3), 248; https://doi.org/10.3390/photonics11030248 - 11 Mar 2024

Viewed by 1369

Abstract

Using tight focusing light, optical tweezers (OT) are tools that can manipulate and capture microscopic particles and biological cells as well as characterize a wide range of micro and nanomaterials. In this paper, we focused on fibroblasts, which are widely used in the biomedical area for a variety of purposes, including promoting human wound healing and preventing the early proliferation of tumor cells. We first built an optical tweezer experimental platform, using an 808 nm continuous-wave laser as the capture light source, to confirm that the device can precisely control the movement of single or multiple particles as well as fibroblasts. Then, a 1030 nm femtosecond laser was employed as the capture light source to study the manipulation of microparticles and fibroblasts at different powers. Lastly, a protracted manipulation protocol was used to prevent the fibroblasts from adhering to the wall. This method can be used to isolate and precisely block adherent growth of fibroblasts in cell populations. This experimental result can be further extended to other biological cells. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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14 pages, 3928 KiB

Open AccessArticle

Probing Layered Tissues by Backscattering Mueller Matrix Imaging and Tissue Optical Clearing

by Qizhi Lai, Tongjun Bu, Tongyu Huang, Yanan Sun, Yi Wang and Hui Ma

Photonics 2024, 11(3), 237; https://doi.org/10.3390/photonics11030237 - 5 Mar 2024

Viewed by 1198

Abstract

Polarization imaging is a label-free and non-invasive technique that is sensitive to microstructure and suitable for probing the microstructure of living tissues. However, obtaining deep-layer information from tissues has been a challenge for optical techniques. In this work, we used tissue optical clearing (TOC) to increase optical penetration depth and characterize the layered structures of tissue samples. Different tissue phantoms were constructed to examine changes in the polarization features of the layered structure during the TOC process. We found that depolarization and anisotropy parameters were able to distinguish between single-layer and double-layer phantoms, reflecting microstructural information from each layer. We observed changes in polarization parameter images during the TOC process and, by analyzing different regions of the images, explained the sensitivity of these parameters to double-layer structures and analyzed the influence of oblique incident illumination. Finally, we conducted TOC experiments on living skin samples, leveraging the experience gained from phantom experiments to identify the double-layer structure of the skin and extract features related to layered structures. The results show that the combination of backscattering polarization imaging and tissue optical clearing provides a powerful tool for the characterization of layered samples. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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9 pages, 3910 KiB

Open AccessCommunication

A Miniaturized Electrothermal-MEMS-Based Optical Coherence Tomography (OCT) Handheld Microscope

by Qian Chen, Hui Zhao, Tingxiang Qi, Hua Wang and Huikai Xie

Photonics 2024, 11(1), 17; https://doi.org/10.3390/photonics11010017 - 26 Dec 2023

Cited by 1 | Viewed by 1685

Abstract

Swept-source optical coherence tomography (SS-OCT), benefiting from its high sensitivity, relatively large penetration depth, and non-contact and non-invasive imaging capability, is ideal for human skin imaging. However, limited by the size and performance of the reported optical galvanometer scanners, existing portable/handheld OCT probes are still bulky, which makes continuously handheld imaging difficult. Here, we reported a miniaturized electrothermal-MEMS-based SS-OCT microscope that only weighs about 25 g and has a cylinder with a diameter of 15 mm and a length of 40 mm. This MEMS-based handheld imaging probe can achieve a lateral resolution of 25 μm, a 3D imaging time of 5 s, a penetration depth of up to 3.3 mm, and an effective imaging field of view (FOV) of 3 × 3 mm². We have carried out both calibration plate and biological tissue imaging experiments to test the imaging performance of this microscope. OCT imaging of leaves, dragonfly, and human skin has been successfully obtained, showing the imaging performance and potential applications of this probe on human skin in the future. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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18 pages, 4822 KiB

Open AccessArticle

Influence of the Spectral Composition of Illuminating Light Sources on Biometric and Phytochemical Characteristics of Ocimum basilicum L.

by Mariya Degtereva, Yevgeniy Levin, Anastasia Gubina, Aleksandr Degterev, Ivan Lamkin, Georgii Konoplev, Sergey Tarasov, Andrei Whaley, Anastasiia Whaley, Ivan Suloev, Alexandra Danilova, Konstantin Gusev and Denis Maimistov

Photonics 2023, 10(12), 1369; https://doi.org/10.3390/photonics10121369 - 13 Dec 2023

Cited by 2 | Viewed by 1830

Abstract

Precise adaptation of the greenhouse lighting spectrum to basic photophysiological processes can effectively and directionally stimulate plant growth and development. The optimal spectrum depends on the plant species and the stage of development and could be assessed empirically. The aim of this study is to determine the LED illumination spectrum that provides a significant improvement in the growth rate and accumulation of biologically active compounds for basil plants (Ocimum basilicum L.) under hydroponic cultivation compared to more traditional lighting sources. The following light sources with various emission spectra were used: an LED lamp within a spectral range of 400–800 nm (B:G:R 15%:5%:80%); a high-pressure sodium lamp (HPS) (B:G:R 5%:45%:50%); a compact fluorescent lamp (B:G:R 20%:40%:40%); a grow LED strip (B:G:R 15%:40%:45%); a white LED lamp (B:G:R 30%:45%:25%); a customized LED lighting setup in color ratios 100%B, 75%B + 25%R, 50%B + 50%R, 25%B + 75%R, 100%R, and natural lighting. A photosynthetic photon flux density (PPFD) of 150 μmol∙m⁻²∙s⁻¹ was provided with all the sources. It was demonstrated reliably that employing the LED strip as an illumination device gives a 112% increase in basil plant yield compared to the HPS; the transpiration coefficient for the LED strip is six times lower than for the HPS. The content of flavonoids in the basil aerial parts on the 30th, 50th, and 70th days of development is 3.2 times higher than for the HPS; the metabolite composition is also more uniform for LED strip lighting. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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9 pages, 3127 KiB

Open AccessEditor’s ChoiceCommunication

Experimental Generation of Structured Light Beams through Highly Anisotropic Scattering Media with an Intensity Transmission Matrix Measurement

by Qiannan Lei, Haokai Gong, Shijie Tu, Yangjian Cai and Qian Zhao

Photonics 2023, 10(7), 737; https://doi.org/10.3390/photonics10070737 - 27 Jun 2023

Cited by 1 | Viewed by 1693

Abstract

Structured light beams have played important roles in the fields of optical imaging and optical manipulation. However, light fields scatter when they encounter highly anisotropic scattering media, such as biological tissue, which destroys their original structured fields and turns them into speckle fields. To reconstruct structured light beams through highly anisotropic scattering media, we present a method based on intensity transmission matrix which only relates the input and output light intensity distributions. Compared with the conventional method which relies on the measurement of complex-valued transmission matrix, our scheme is easy to implement, fast and stable. With the assistance of spatial filters, three kinds of structured light beams, Bessel-like beams, vortex beams and cylindrical vector beams, were constructed experimentally through a ZnO scattering layer. The present method is expected to promote optical applications through highly anisotropic scattering media. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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11 pages, 3306 KiB

Open AccessCommunication

Axial Resolution Enhancement of Optical Sectioning Structured Illumination Microscopy Based on Three-Beam Interference

by Chao Xiao, Xing Li, Jia Qian, Wang Ma, Junwei Min, Peng Gao, Dan Dan and Baoli Yao

Photonics 2023, 10(6), 682; https://doi.org/10.3390/photonics10060682 - 12 Jun 2023

Cited by 1 | Viewed by 1866

Abstract

As a branch of 3D microscopy, optical sectioning structured illumination microscopy (OS-SIM) has the advantages of fast imaging speed, weak photobleaching and phototoxicity, and flexible and compatible configuration. Although the method of using the one-dimensional periodic fringe pattern projected on the sample can remove the out-of-focus background from the in-focus signal, the axial resolution of the final reconstructed 3D image is not improved. Here, we propose a three-beam interference OS-SIM, namely TBOS, instead of the common-used dual-beam interference OS-SIM (DBOS). The three-beam interference scheme has been adopted in 3D super-resolution SIM (3D-SR-SIM), where the fringe phase shifting needs to be along each of the three orientations. In contrast, TBOS applies phase shifting only in one arbitrary direction. We built a TBOS SIM microscope and performed the 3D imaging experiments with 46 nm diameter fluorescent microspheres and a mouse kidney section. The axial resolution of the 3D image obtained with TBOS was enhanced by a factor of 1.36 compared to the DBOS method, consistent with the theoretical analysis and simulation. The OS-SIM with enhanced axial resolution for 3D imaging may find a wide range of applications in the biomedical field. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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10 pages, 2273 KiB

Open AccessCommunication

Extending the Imaging Depth of Field through Scattering Media by Wavefront Shaping of Non-Diffraction Beams

by Tongyu Han, Tong Peng, Runze Li, Kaige Wang, Dan Sun and Baoli Yao

Photonics 2023, 10(5), 497; https://doi.org/10.3390/photonics10050497 - 26 Apr 2023

Cited by 4 | Viewed by 1969

Abstract

Increasing the depth of field (DOF) is a crucial issue for imaging through scattering media. In this paper, an improved genetic algorithm is used to modulate the wavefront of light through scattering media, by which high-quality refocusing and imaging through scattering media are achieved. Then, the DOF of the imaging system is effectively extended by further modulating the refocused beam into a non-diffraction beam. Two kinds of non-diffraction beams, i.e., a Bessel beam and Airy beam, were produced as a demonstration. The experimental results show that compared to the Gaussian beam, the DOF of the imaging system by combining the wavefront shaping and non-diffraction Bessel beam or Airy beam can be improved by a factor of 1.1 or 1.5, respectively. The proposed method is helpful for the technical development of high-quality imaging through scattering media with a large DOF. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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Review

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13 pages, 2844 KiB

Open AccessReview

Leveraging Optical Coherence Tomography and Angiography Artifacts to Identify Clinicopathological Correlates in Macular Disorders

by Luca Scuderi, Serena Fragiotta, Chiara Ciancimino, Marco Mafrici, Marco Mazzola, Monica Varano, Tommaso Rossi and Mariacristina Parravano

Photonics 2024, 11(10), 991; https://doi.org/10.3390/photonics11100991 - 21 Oct 2024

Viewed by 635

Abstract

Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA) are pivotal imaging techniques in diagnosing and managing macular disorders, providing high-resolution cross-sectional images of the retina. Although OCT artifacts are often deemed undesirable, they can paradoxically offer valuable insights into retinal pathology. This review explores the potential of OCT and OCTA artifacts to serve as indicators of pathological correlates in various macular conditions. The study emphasizes the importance of recognizing and leveraging these artifacts to refine clinicopathologic correlates characterizing several macular disorders, including age-related macular degeneration, diabetic retinopathy, and retinal vascular occlusive disease. OCT artifacts can reflect the ultrastructure and composition of pathological features, and their recognition can thus expand the understanding of the pathogenesis and improve the diagnostic interpretation of macular disorders. With the widespread use of OCT and OCTA technologies, identifying artifacts with clinicopathologic significance is of paramount importance and may have significant implications for management and prognosis. Full article

(This article belongs to the Special Issue Technologies and Applications of Biophotonics)

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