Miniaturization of Laser Doppler Vibrometers—A Review

Li, Yanlu; Dieussaert, Emiel; Baets, Roel

doi:10.3390/s22134735

Cited by 21 publications

(8 citation statements)

References 138 publications

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“…The Doppler frequency shift of the reflected light, which is proportional to the instantaneous velocity of the DUT, can be retrieved from the combined signals with proper demodulation algorithms. Generally, heterodyne methods and homodyne methods [7] can be used. In the on-chip LDV, we are using a homodyne method because of the lack of an efficient frequency shifter on the chip.…”

Section: System Design and Measurement Setupmentioning

confidence: 99%

Laser Doppler vibrometry sensors implemented in a silicon photonic integrated circuit for measuring cardiovascular signals on bare skin

Aasmul

Bakoz³

et al. 2023

Diagnostic and Therapeutic Applications of Light in Cardiology 2023

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Laser Doppler vibrometer (LDV) sensors can measure skin vibrations originating from propagating superficial arterial pulse waves, which can be used to assess arterial stiffness and identify stenosis and heart failure. A key challenge is to get sufficient diffusely reflected power from bare skin in order to avoid the use of a retroreflective patch. Here we report a prototype, enabled by silicon photonics, that can directly measure the vibrations of bare human skin. We demonstrate a resolution better than 10 pm/sqrt(Hz) when the skin surface is placed at the focal plane of the sensing beams. This result holds great promise for the targeted cardiovascular applications.

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Section: System Design and Measurement Setupmentioning

confidence: 99%

Laser Doppler vibrometry sensors implemented in a silicon photonic integrated circuit for measuring cardiovascular signals on bare skin

Aasmul

Bakoz³

et al. 2023

Diagnostic and Therapeutic Applications of Light in Cardiology 2023

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“…Laser Doppler vibrometers (LDVs) have also been used to detect photoacoustic signals. [12][13][14] These systems are typically based on free-space or fiber optics, which can be expensive and bulky. In this work, we present a photonic integrated circuit (PIC)-based homodyne LDV for compact, optical-based detection of photoacoustic signals.…”

Section: Introductionmentioning

confidence: 99%

Silicon photonics based laser doppler vibrometer for non-contact photoacoustic sensing

Dieussaert

Baets

2023

Smart Photonic and Optoelectronic Integrated Circuits 2023

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Non-contact detection of photoacoustic signals is important for various applications, particularly in medical sensing and imaging, where contact methods can be uncomfortable or risky for the patient. Techniques using optical detection of vibrations, such as laser doppler vibrometers (LDVs), have been proven to be a key component for enabling non-contact photoacoustic sensing. However, most LDV systems rely on fiber-based or free-space optics, which can be unwieldy and expensive, especially for multiple location sensing. In this work, we present a compact, photonic integrated circuit (PIC)-based homodyne LDV system for the detection of photoacoustic signals. The system is fabricated on a silicon-on-insulator platform, which has the potential to be low-cost in case of medium or large volume production. To generate the photoacoustic signals, we used a 532 nm pulsed laser directed towards a target embedded in a silicone phantom designed to mimic the acoustic properties of human tissue. The target consists of an ink-solution-filled channel, which absorbs the excitation light and generates acoustical signals within the phantom through the photoacoustic effect. After performing a series of measurements with different ink concentrations, we found a good correlation between the photoacoustic signals detected by the on-chip detectors and the absorption of the target. Our system was able to detect ink solutions with absorption values as low as 5 cm −1 , an order of magnitude lower than the typical absorption of whole blood at 532 nm. These results demonstrate that PIC-based LDVs can be used to realize compact and low-cost non-contact detection for photoacoustic biomedical sensing applications.

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“…[18] It allows high frequency (up to GHz), high sensitivity (accuracy down to picometer), and fast speed 3D mapping in real-time, which has been employed in a wide field, such as ve- locity monitoring and ultrasound mapping. However, it requires specialized and often costly equipment, and the miniaturization of such techniques [19] and the line-of-sight [20] limit in free-space optics remain challenging for wider biomedical applications. Efficient fabrication of free-standing ME membranes with tailorable size is another problem to be addressed for the purpose of integration with sophisticated devices of various geometries.…”

Section: Introductionmentioning

confidence: 99%

Low‐Field Actuating Magnetic Elastomer Membranes Characterized using Fibre‐Optic Interferometry

Li,

Coote,

Subburaman

et al. 2023

Adv Funct Materials

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Smart robotic devices remotely powered by magnetic field have emerged as versatile tools for wide biomedical applications. Soft magnetic elastomer (ME) composite membranes with high flexibility and responsiveness are frequently incorporated to enable local actuation for wireless sensing or cargo delivery. However, the fabrication of thin ME membranes with good control in geometry and uniformity remains challenging, as well as the optimization of their actuating performances under low fields (milli‐Tesla). In this work, the development of ME membranes comprising of low‐cost magnetic powder and highly soft elastomer through a simple template‐assisted doctor blading approach, is reported. The fabricated ME membranes are controllable in size (up to centimetre‐scale), thickness (tens of microns) and high particle loading (up to 70 wt.%). Conflicting trade‐off effects of particle concentration upon magnetic responsiveness and mechanical stiffness are investigated and found to be balanced off as it exceeds 60 wt.%. A highly sensitive fibre‐optic interferometric sensing system and a customized fibre‐ferrule‐membrane probe are first proposed to enable dynamic actuation and real‐time displacement characterization. Free‐standing ME membranes are magnetically excited under low field down to 2 mT, and optically monitored with nanometer accuracy. The fast and consistent responses of ME membranes showcase their promising biomedical applications in nanoscale actuation and sensing.

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Miniaturization of Laser Doppler Vibrometers—A Review

Cited by 21 publications

References 138 publications

Laser Doppler vibrometry sensors implemented in a silicon photonic integrated circuit for measuring cardiovascular signals on bare skin

Laser Doppler vibrometry sensors implemented in a silicon photonic integrated circuit for measuring cardiovascular signals on bare skin

Silicon photonics based laser doppler vibrometer for non-contact photoacoustic sensing

Low‐Field Actuating Magnetic Elastomer Membranes Characterized using Fibre‐Optic Interferometry

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