This work presents an overview of progress and developments in the field of fiber optic sensor technology, highlighting the major issues underpinning recent research and illustrating a number of important applications and key areas of effective fiber optic sensor development.

http://snake.persiangig.com/document/sensor1.pdf

Fiber optic sensor technology: an overview

Robotic medical instrument systems and associated methods utilizing an optical fiber sensors such as Bragg sensor optical fibers. In one configuration, an optical fiber is coupled to an elongate instrument body and includes a fiber core having one or more Bragg gratings. A controller is configured to initiate various actions in response thereto. For example, a controller may generate and display a graphical representation of the instrument body and depict one or more position and/or orientation variables thereof, or adjust motors of an instrument driver to reposition the catheter or another instrument. Optical fibers having Bragg gratings may also be utilized with other system components including a plurality of working instruments that are positioned within a sheath lumen, an instrument driver, localization sensors, and/or an image capture device, and may also be coupled to a patient's body or associated structure that stabilizes the body.

Robotic instrument systems and methods utilizing optical fiber sensors

A medical sensor may be adapted to account for factors that cause irregularities in pulse oximetry measurements or other spectrophotemetric measurements. Sensors are provided with surface features that reduce the amount of outside light or shunted light that impinge the detecting elements of the sensor. The sensor is adapted to reduce the effect of outside light or shunted light on pulse oximetry measurements.

Medical sensor and technique for using the same

Heart rate measurement based on a time-lapse image.

A non-invasive optical sensor which uses the motion signal to calculate the physiological characteristic being measured. For pulse oximetry, a least squares or a ratio-of-ratios technique can be applied to the motion signal itself. This is made possible by selecting a site on the patient where variations in motion produce signals of two wavelengths which are sufficiently correlated. In particular, it has been determined that a sensor placed on a nail, in particular a thumbnail, exhibits the characteristics of having the red and infrared signals correlated when used for pulse oximetry, and the resulting signals correlate to arterial oxygen saturation.

Motion compatible sensor for non-invasive optical blood analysis

The Fiber Optic Respiratory Plethysmograph (FORP) is a non-invasive instrument for respiratory and heart monitoring in humans, based on the design of the Respiratory Inductive Plethysmograph (RIP. The FORP uses two sensors at thoracic and abdominal levels that measure circumferences rather than the cross sectional areas measured by the RIP. Each sensor is made of a specifically looped optical fiber that responds to elongation with variation in light transmission, via the macrobending loss effect. The design and construction of the original version of the FORP has been reported previously 1. This paper presents the results of a new figure-of-eight construction for the fiber loops. The resulting system shows greater signal range, increased linearity and less hysteresis than former constructions. Results are presented detailing the calibration of the respiratory measurements against a spirometer using a range of calibration protocols, one based on isovolume breathing and others on a Least Mean Square (LMS) fit. Additional improvements to signal processing and the increased sensitivity of the new design now make it practicable to detect torso motion arising from cardiac activity. This paper also presents results showing the simultaneous monitoring of respiratory and cardiac signals, using only the FORP transducers.

Construction and calibration of a new design of fiber optic respiratory plethysmograph (FORP)

The macro-bending loss effect in optical fibres has been used to redevelop a sensor for the measurement of thoracic and abdominal circumferences in non-invasive respiratory monitoring. The new sensor uses a novel figure-of-eight loop configuration, which results in increased linearity of response, less mechanical resistance and hysteresis, as well as other benefits. The performance of the new sensor as applied to respiratory monitoring is examined, and indicates a higher resolution and sensitivity than the old. This enhanced performance enables measurement of respiratory and cardiac function using the same transducing fibre.

https://iopscience.iop.org/article/10.1088/0967-3334/26/5/001/pdf

Improved fibre optic respiratory monitoring using a figure-of-eight coil.

A new instrumental method for measuring the physical properties of a liquid has been developed. The instrument, called a capacitive drop tensiometer (CDT), is based on the drop volume principle in combination with a capacitive transducer. A delivery head with a specialized wetting design was constructed for forming drops. The capacitive transducer uses the delivery head as one of its plates and a cylindrical ring plate, which surrounds the delivery head and the space occupied by the drop that is formed, as another. Excellent linearity is achieved by optimizing the design, with an accuracy of drop volume measurement of approximately . The system is suitable for measuring both drops in equilibrium and those in the process of growing. Its capability of real-time measurement makes it particularly useful for volatile liquids, in which instance the measurement of drop volume using a flowmeter or a pump is no longer reliable. The CDT can also be used to determine concentration. It was found that the concentration curve is linear for aqueous glycerol solutions although not so for aqueous ethanol solutions. The CDT's ability to measure surface tension was also explored and experimental results are presented here.

https://iopscience.iop.org/article/10.1088/0957-0233/10/1/007/pdf

The capacitive drop tensiometer: a novel multianalysing technique for measuring the properties of liquids

An apparatus for use in characterising liquids by obtaining a fingerprint of the liquid. This allows one to measure a property of a liquid, and thereby distinguish between liquids. The apparatus comprises means for directing acoustic energy at a sample of the liquid, which is preferably in the form of a drop, and means for deriving a signal related to the interaction of the acoustic energy with the liquid sample. The drop may change in volume or shape during the measurements, to derive additional properties of the liquid. The apparatus and method of the invention are used in distinguishing and analysing a variety of liquid samples.

J. Mason

Papers

Construction and calibration of a new design of fiber optic respiratory plethysmograph (FORP)

Improved fibre optic respiratory monitoring using a figure-of-eight coil.

The capacitive drop tensiometer: a novel multianalysing technique for measuring the properties of liquids

Apparatus and method for measuring a property of a liquid

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