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Gupta K, Shenoy MR. Compact setup to determine size and concentration of spherical particles in a turbid medium. APPLIED OPTICS 2021; 60:8174-8180. [PMID: 34613081 DOI: 10.1364/ao.435596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
We propose a compact setup to determine the size and concentration of spherical particles in a turbid medium. A pair of plane mirrors is used to multifold the undeviated laser beam, and measure it at a detector placed close to the sample, to determine the interaction coefficient. The size of particles is uniquely determined by comparison of the scattered light from the medium, measured at two separate detectors placed at two different angular positions, with that from Monte Carlo simulations. The methodology is verified using measurements with turbid samples comprising polystyrene spheres.
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Li H, Wang Z, Cao Y, Ma Y, Feng X. Optical difference in the frequency domain to suppress disturbance for wearable electronics. BIOMEDICAL OPTICS EXPRESS 2020; 11:6920-6932. [PMID: 33408970 PMCID: PMC7747917 DOI: 10.1364/boe.403033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/07/2020] [Accepted: 10/11/2020] [Indexed: 06/12/2023]
Abstract
Measurements based on optics offer a wide range of unprecedented opportunities in the biological application due to the noninvasive or non-destructive detection. Wearable skin-like optoelectronic devices, capable of deforming with the human skin, play significant roles in future biomedical engineering such as clinical diagnostics or daily healthcare. However, the detected signals based on light intensity are very sensitive to the light path. The performance degradation of the wearable devices occurs due to device deformation or motion artifact. In this work, we propose the optical difference in the frequency domain of signals for suppressing the disturbance generated by wearable device deformation or motion artifact during the photoplethysmogram (PPG) monitoring. The signal processing is simulated with different input waveforms for analyzing the performance of this method. Then we design and fabricate a wearable optoelectronic device to monitor the PPG signal in the condition of motion artifact and use the optical difference in the frequency domain of signals to suppress irregular disturbance. The proposed method reduced the average error in heart rate estimation from 13.04 beats per minute (bpm) to 3.41 bpm in motion and deformation situations. These consequences open up a new prospect for improving the performance of the wearable optoelectronic devices and precise medical monitoring in the future.
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Affiliation(s)
- Haicheng Li
- AML, Department of Engineering Mechanics, Tsinghua University, Beijing, 100084, China
- Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, China
| | - Zhouheng Wang
- AML, Department of Engineering Mechanics, Tsinghua University, Beijing, 100084, China
- Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, China
| | - Yu Cao
- AML, Department of Engineering Mechanics, Tsinghua University, Beijing, 100084, China
- Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, China
| | - Yinji Ma
- AML, Department of Engineering Mechanics, Tsinghua University, Beijing, 100084, China
- Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, China
| | - Xue Feng
- AML, Department of Engineering Mechanics, Tsinghua University, Beijing, 100084, China
- Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, China
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Blomqvist KH, Kärkkäinen L. Differential photoplethysmogram sensor with an optical notch filter shows potential for reducing motion artifact signals. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aac57c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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