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Surface Plasmon Resonance Optical Sensor: A Review on Light Source Technology
The notion of surface plasmon resonance (SPR) sensor research emerged more than eight decades ago from the first observed phenomena in 1902 until the first introduced principles for gas sensing and biosensing in 1983. The sensing platform has been hand-in-hand with the plethora of sensing technology advancement including nanostructuring, optical technology, fluidic technology, and light source technology, which contribute to substantial progress in SPR sensor evolution. Nevertheless, the commercial products of SPR sensors in the market still require high-cost investment, component, and operation, leading to unaffordability for their implementation in a low-cost point of care (PoC) or laboratories. In this article, we present a comprehensive review of SPR sensor development including the state of the art from a perspective of light source technology trends. Based on our review, the trend of SPR sensor configurations, as well as its methodology and optical designs are strongly influenced by the development of light source technology as a critical component. These simultaneously offer new underlying principles of SPR sensor towards miniaturization, portability, and disposability features. The low-cost solid-state light source technology, such as laser diode, light-emitting diode (LED), organic light emitting diode (OLED) and smartphone display have been reported as proof of concept for the future of low-cost SPR sensor platforms. Finally, this review provides a comprehensive overview, particularly for SPR sensor designers, including emerging engineers or experts in this field.
Journal Article
Opto-VLSI devices and circuits for biomedical and healthcare applications
\"The text comprehensively discusses the latest Opto-VLSI devices and circuits useful for healthcare and biomedical applications. It further emphasizes the importance of smart technologies such as artificial intelligence, machine learning, and the internet of things for the biomedical and healthcare industries\"-- Provided by publisher.
BOOK
Validation of Polar OH1 optical heart rate sensor for moderate and high intensity physical activities
Optical measurement techniques and recent advances in wearable technology have made heart rate (HR) sensing simpler and more affordable.
The Polar OH1 is an arm worn optical heart rate monitor. The objectives of this study are two-fold; 1) to validate the OH1 optical HR sensor with the gold standard of HR measurement, electrocardiography (ECG), over a range of moderate to high intensity physical activities, 2) to validate wearing the OH1 at the temple as an alternative location to its recommended wearing location around the forearm and upper arm.
Twenty-four individuals participated in a physical exercise protocol, by walking on a treadmill and riding a stationary spin bike at different speeds while the criterion measure, ECG and Polar OH1 HR were recorded simultaneously at three different body locations; forearm, upper arm and the temple. Time synchronised HR data points were compared using Bland-Altman analyses and intraclass correlation.
The intraclass correlation between the ECG and Polar OH1, for the aggregated data, was 0.99 and the estimated mean bias ranged 0.27-0.33 bpm for the sensor locations. The three sensors exhibited a 95% limit of agreement (LoA: forearm 5.22, -4.68 bpm; upper arm 5.15, -4.49; temple 5.22, -4.66). The mean of the ECG HR for the aggregated data was 112.15 ± 24.52 bpm. The intraclass correlation of HR values below and above this mean were 0.98 and 0.99 respectively. The reported mean bias ranged 0.38-0.47 bpm (95% LoA: forearm 6.14, -5.38 bpm; upper arm 6.07, -5.13 bpm; temple 6.09, -5.31 bpm), and 0.15-0.16 bpm (95% LoA: forearm 3.99, -3.69 bpm; upper arm 3.90, -3.58 bpm; temple 4.06, -3.76 bpm) respectively. During different exercise intensities, the intraclass correlation ranged 0.95-0.99 for the three sensor locations. During the entire protocol, the estimated mean bias was in the range -0.15-0.55 bpm, 0.01-0.53 bpm and -0.37-0.48 bpm, for the forearm, upper arm and temple locations respectively. The corresponding upper limits of 95% LoA were 3.22-7.03 bpm, 3.25-6.82 bpm and 3.18-7.04 bpm while the lower limits of 95% LoA were -6.36-(-2.35) bpm, -6.46-(-2.30) bpm and -7.42-(-2.41) bpm.
Polar OH1 demonstrates high level of agreement with the criterion measure ECG HR, thus can be used as a valid measure of HR in lab and field settings during moderate and high intensity physical activities.
Journal Article
Recent Development of Tunable Optical Devices Based on Liquid
Liquid opens up a new stage of device tunability and gradually replaced solid-state devices and mechanical tuning. It optimizes the control method and improves the dynamic range of many optical devices, exhibiting several attractive features, such as rapid prototyping, miniaturization, easy integration and low power consumption. The advantage makes optical devices widely used in imaging, optical control, telecommunications, autopilot and lab-on-a-chip. Here, we review the tunable liquid devices, including isotropic liquid and anisotropic liquid crystal devices. Due to the unique characteristics of the two types of liquids, the tuning principles and tuning methods are distinguished and demonstrated in detail firstly and then some recent progress in this field, covering the adaptive lens, beam controller, beam filter, bending waveguide, iris, resonator and display devices. Finally, the limitations and future perspectives of the current liquid devices are discussed.
Journal Article
Reconfigurable Micro/Nano‐Optical Devices Based on Phase Transitions: From Materials, Mechanisms to Applications
In recent years, numerous efforts have been devoted to exploring innovative micro/nano‐optical devices (MNODs) with reconfigurable functionality, which is highly significant because of the progressively increasing requirements for next‐generation photonic systems. Fortunately, phase change materials (PCMs) provide an extremely competitive pathway to achieve this goal. The phase transitions induce significant changes to materials in optical, electrical properties or shapes, triggering great research interests in applying PCMs to reconfigurable micro/nano‐optical devices (RMNODs). More specifically, the PCMs‐based RMNODs can interact with incident light in on‐demand or adaptive manners and thus realize unique functions. In this review, RMNODs based on phase transitions are systematically summarized and comprehensively overviewed from materials, phase change mechanisms to applications. The reconfigurable optical devices consisting of three kinds of typical PCMs are emphatically introduced, including chalcogenides, transition metal oxides, and shape memory alloys, highlighting the reversible state switch and dramatic contrast of optical responses along with designated utilities generated by phase transition. Finally, a comprehensive summary of the whole content is given, discussing the challenge and outlooking the potential development of the PCMs‐based RMNODs in the future.
Reconfigurable micro/nano‐optical devices (RMNODs) are particularly significant for their optical responses can be reversibly modulated, further enabling unprecedented opportunities for next‐generation photonic systems. This review systematically summarizes the RMNODs based on phase transitions, spanning from materials and phase change mechanisms to applications. The RMNODs consisting of chalcogenides, transition metal oxides, and shape memory alloys are emphatically introduced.
Journal Article
Three-dimensional super-resolution longitudinal magnetization spot arrays
We demonstrate an all-optical strategy for realizing spherical three-dimensional (3D) super-resolution (∼
λ
3
/22) spot arrays of pure longitudinal magnetization by exploiting a 4
π
optical microscopic setup with two high numerical aperture (NA) objective lenses, which focus and interfere two modulated vectorial beams. Multiple phase filters (MPFs) are designed via an analytical approach derived from the vectorial Debye diffraction theory to modulate the two circularly polarized beams. The system is tailored to constructively interfere the longitudinal magnetization components, while simultaneously destructively interfering the azimuthal ones. As a result, the magnetization field is not only purely longitudinal but also super-resolved in all three dimensions. Furthermore, the MPFs can be designed analytically to control the number and locations of the super-resolved magnetization spots to produce both uniform and nonuniform arrays in a 3D volume. Thus, an all-optical control of all the properties of light-induced magnetization spot arrays has been demonstrated for the first time. These results open up broad applications in magnetic-optical devices such as confocal and multifocal magnetic resonance microscopy, 3D ultrahigh-density magneto-optic memory, and light-induced magneto-lithography.
Magneto-optics: sub-wavelength magnetization
A scheme for making 3D arrays of subwavelength magnetization spots will benefit the high-density data storage and magnetic resonance microscopy. Zhong-Quan Nie and co-workers used two high-numerical-aperture lenses to focus and interfere a pair of circularly polarized Bessel Gaussian beams. They used spatial light modulators to modulate the wavefronts of the two beams in such a way that enhanced longitudinal magnetization components through constructive interference and simultaneously cancelled the azimuthal components by deconstructive interference. This generated an array of super-resolution spots of pure longitudinal magnetization. The number and location of the spots can be varied by changing the signal sent to the spatial light modulator. This is the first demonstration of all-optical control of all the properties of light-induced magnetization spot arrays and is promising for developing the light-induced magnetic data storage and lithography devices.
Journal Article
Plasmonic circuits for manipulating optical information
Surface plasmons excited by light in metal structures provide a means for manipulating optical energy at the nanoscale. Plasmons are associated with the collective oscillations of conduction electrons in metals and play a role intermediate between photonics and electronics. As such, plasmonic devices have been created that mimic photonic waveguides as well as electrical circuits operating at optical frequencies. We review the plasmon technologies and circuits proposed, modeled, and demonstrated over the past decade that have potential applications in optical computing and optical information processing.
Journal Article
Elastomeric lenses with tunable astigmatism
Microlenses fabricated using flexible elastomers can be tuned in focal length by application of controlled strain. By varying the strain azimuthally, the lenses may be deformed asymmetrically such that aberrations may be controlled. This approach is used to tune the astigmatism of the tunable lenses, and it is shown that the generated wavefront may be accurately controlled. The lens presented here has an initial focal length of 32.6 mm and a tuning range of +2.3 mm for approximately 10% applied strain. The range of directly tunable Zernike polynomials representing astigmatism is about 3 µm, while the secondary lens errors, which cannot be tuned directly, vary only by about 0.2 µm.
Photonics: tunable, elastic lenses
Hans Zappe and colleagues at the University of Freiburg in Germany have realized elastic lenses whose properties can be controlled by strain. Small, tunable polymer lenses are of interest for micro-optical applications, for example, in miniaturized imaging systems. The focal length of such a lens can be adjusted by an externally applied strain, as this changes the shape of the lens. The researchers used eight mechanical anchors placed around the circumference of the lens to apply different strains at various lens positions. This achieved a complex deformation pattern on the surface, which allowed control over not only the lens’ focal length, but also its astigmatism. Controlling such lens aberrations is important for micro-optical devices that, unlike the multiple-lens arrays used in microscope objectives, use as few lenses as possible.
Journal Article
Semiconductor nanocrystal quantum dots : synthesis, assembly, spectroscopy and applications
This is the first book to specifically focus on semiconductor nanocrystals, and address their synthesis and assembly, optical properties and spectroscopy, and potential areas of nanocrystal-based devices.
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