A new single-fibre laser Doppler flowmeter based on digital signal processing

Cai, Hongming; Pettersson, Hans; Rohman, H.; Larsson, Sven‐Erik; Öberg, Peter

doi:10.1016/1350-4533(95)00008-9

Cited by 9 publications

(9 citation statements)

References 13 publications

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“…Laser Doppler systems are difficult to calibrate in vivo (Oberg 1990), consequently a number of in vitro techniques have been developed (Mito 1992, Cai et al 1996, Liebert et al 1998). These models do not reflect the scale, complexity or variability of skin tissue, site to site or subject to subject.…”

Section: Methodsmentioning

confidence: 99%

“…If the scattering system is implemented as a solid block with embedded particles, a rotational or linear actuator is required to provide motion. For example, Mito (1992) used a simple rotating turntable to obtain a Doppler signal, whereas Cai et al (1996) employed a complex linear drive table. A major benefit of using a rotational scattering block is the ease of reproducibility and control of particle velocity.…”

Section: Scattering Media For Calibrationmentioning

confidence: 99%

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An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot

Cobb¹,

Claremont²

2001

Medical Engineering & Physics

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An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot. Jonathan Edwin CobbPlantar ulceration is a complication of the diabetic foot prevalent in adults with type 11 diabetes mellitus. Although neuropathy, microvascular disease and biornechanical factors are all implicated, the mechanism by which the tissue becomes pre-disposed to damage remains unclear. Recent theories suggest that the nutritional supply to the tissue is compromised, either by increased flow through the arteriovenous anastomoses ('capillary steal' theory) or through changes in the micro vascu I ature (haemodynamic hypothesis). Clinical data to support these ideas has been limited to assessment of the unclad foot under rest conditions. A limitation of previous studies has been the exclusion of static and dynamic tissue loading, despite extensive evidence that these biornechanical factors are essential in the development of plantar ulceration. The present study has overcome these problems by allowing assessment of plantar blood flow, in-shoe, during standing and walking.The system comprises a laser Doppler blood flux sensor operating at 780nm, load sensor, measurement shoe, instrumentation, and analysis software. In-vitro calibration was performed using standard techniques. An in-vivo study of a small group of diabetic subjects indicated differences in the blood flux response between diabetic neuropaths, diabetics with vascular complications and a control group. For example, following a loading period of 120s, relative increases in response from rest to peak were: Control (150% to 259%), Vascular (-70% to 242%), Neuropathic (109%-174%) and recovery times to 50% of the peak response were: Control (33s to 45s), Vascular (43s to >120s), Neuropathic (>120s). Dynamic re-perfusion rates (arbitrary units per millisecond) obtained for the swing phase of gait were: Control (6.1 a. u/ms to 7.9 a. u/ms), Vascular (4 a. u/ms to 6.2 a. u/ms), Neuropathic (2.3 a. u/ms to 4.5 a. u/ms).

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Section: Methodsmentioning

confidence: 99%

Section: Scattering Media For Calibrationmentioning

confidence: 99%

An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot

Cobb¹,

Claremont²

2001

Medical Engineering & Physics

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“…A number of different techniques have previously been employed to study skin microcirculation such as capillaroscopy [13, 14], cold challenge tests [15–17], laser Doppler flowmetry (LDF) [18–22], thermography [16, 23, 24], and measurement of transcutaneous oxygen tension [25–27]. However, to date, no diagnostic test has been universally implemented for aiding in the diagnosis of primary RP [6].…”

Section: Introductionmentioning

confidence: 99%

“…LDF is a valuable, noninvasive method of analyzing microcirculatory changes in RP [18–22, 28]. It measures the flux of blood cells in a designated area, making it well suited to monitor transient alterations in skin circulation, as well as determine general perfusion [29–32].…”

Section: Introductionmentioning

confidence: 99%

Postocclusive Hyperemia Measured with Laser Doppler Flowmetry and Transcutaneous Oxygen Tension in the Diagnosis of Primary Raynaud’s Phenomenon: A Prospective, Controlled Study

Maga

Henry

Kmiotek

et al. 2016

BioMed Research International

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The aim of this study was to measure the sensitivity and specificity of transcutaneous oxygen tension and postocclusive hyperemia testing using laser Doppler flowmetry in patients with primary Raynaud's phenomenon. One hundred patients and one hundred controls were included in the study. Baseline microvascular blood flow and then time to peak flow following occlusion were measured using laser Doppler flowmetry. Afterwards, the transcutaneous oxygen tension was recorded. The sensitivities of baseline microvascular blood flow, postocclusive time to peak flow, and transcutaneous oxygen tension were 79%, 79%, and 77%, respectively. The postocclusive time peak flow had a superior specificity of 90% and area under the curve of 0.92 as compared to 66% and 0.80 for baseline microvascular flow and 64% and 0.76 for transcutaneous oxygen tension. Time to postocclusive peak blood flow measured by laser Doppler flowmetry is a highly accurate test for differentiating patients with primary Raynaud's phenomenon from healthy controls.

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“…The high accuracy is shadowed by the complex sensor structure and the system adjustment process is difficult due to the Michelson's interferometer principle and the Coriolis effect. Doppler effect-based fiber-optic flow sensors are proposed for the medical field [5,6], such as a hemodromometer. Most of the above uses interference principle.…”

Section: Introductionmentioning

confidence: 99%

Optical fiber‐based macrobend free air flow sensor using a hinge joint: A preliminary report

Vijayan

Thakare

Karekar

et al. 2008

Micro & Optical Tech Letters

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7. As the three horns are highly optimized, we also checked that the return loss (RL) did not have any spikes in the band of interest. We have used CST MicroWave Studio to calculate a RL-sweep for each of the horns. As can be seen in Figure 10, the RL is better than 20 dB across each band for the three horns and do not show any spikes.Only two of the horns have been manufactured and tested to date and measurements agreed well with the theoretical predictions. ACKNOWLEDGMENTThe authors thank S.J. Barker for measuring the radiation patterns of the horns and A. Dunning for the return loss measurements.

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A new single-fibre laser Doppler flowmeter based on digital signal processing

Cited by 9 publications

References 13 publications

An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot

An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot

Postocclusive Hyperemia Measured with Laser Doppler Flowmetry and Transcutaneous Oxygen Tension in the Diagnosis of Primary Raynaud’s Phenomenon: A Prospective, Controlled Study

Optical fiber‐based macrobend free air flow sensor using a hinge joint: A preliminary report

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