Optical imaging system with multiple imaging channel optical sensing

An optical imaging system for use with an infusion tube including: at least one light source for emitting at least two of first, second, or third spectrums of light; an optics system including a single lens for receiving and transmitting at least two of the first spectrum light transmitted through a first portion of the chamber, the second spectrum light transmitted through a second portion of the chamber, or the third spectrum light transmitted through a third portion of the chamber. The system includes a sensor receiving the at least two of the spectrums from the lens and generating and transmitting data characterizing the at least two of the spectrums. The system includes a memory element storing computer readable instructions and a processor to execute the instructions to generate, using the data, at least two of first, second, or third images of the first, second, and third portions, respectively.

TECHNICAL FIELD

The present disclosure relates generally to an infusion pump with chromatic multiplexing, in particular, the pump uses single or multiple light sources, a single lens, mirrors, and beam combiners to enable use of a single color image sensor to provide distinct images for multiple distinct portions of the pump.

BACKGROUND

Monochrome image sensors are generally less costly than color image sensors. However, for simultaneously received multiple images, monochrome sensors cannot be used to separate the respective images, for example to generate, display, or operate upon the respective images, using conventional signal processing. For example, when a pixel in the monochrome sensor receives light, the sensor cannot determine which of the respective images the light pertains to.

SUMMARY

According to aspects illustrated herein, there is provided an optical imaging system for use with an infusion tube having a drip chamber including a first portion with a drip tube, a second portion with an exit port, and a third portion located between the first and second portions, the optical imaging system including: at least one light source for emitting at least two of first, second, or third spectrums of light; an optics system including a single lens for receiving and transmitting at least two of the first spectrum of light transmitted through the first portion, the second spectrum of light transmitted through the second portion, or the third spectrum of light transmitted through the third portion. The optical system includes a single image sensor for receiving the at least two of the first, second, or third spectrums of light from the single lens and generating and transmitting data characterizing the at least two of the first, second, or third spectrums of light received from the single lens. The imaging system includes a memory element for storing computer executable instructions; and at least one processor configured to execute the computer executable instructions to generate, using the data, at least two of first, second, or third images of the first, second, or third portions, respectively.

According to aspects illustrated herein, there is provided an optical imaging system for use with an infusion tube having a drip chamber including a first portion with a drip tube, a second portion with an exit port, and a third portion located between the first and second portions, the optical imaging system including: a single light source for emitting at least two of first, second, or third spectrums of light; and an optics system including a single lens for receiving and transmitting at least two of: the first spectrum of light transmitted through the first portion; the second spectrum of light transmitted through the second portion; and the third spectrum of light transmitted through the third portion; and a single color image sensor for: receiving the at least two of the first, second, or third spectrums of light from the single lens; and generating and transmitting data characterizing the at least two of the first, second, or third spectrums of light received from the single lens. The imaging system includes a memory element for storing computer executable instructions, and at least one processor configured to execute the computer executable instructions to generate, using the data, at least two of first, second, or third images of the first, second, or third portions, respectively.

According to aspects illustrated herein, there is provided an optical imaging system for use with an infusion tube having a drip chamber including a first portion with a drip tube, a second portion with an exit port, and a third portion located between the first and second portions. The optical imaging system includes: at least one of a first light source for emitting a first spectrum of light only, a second light source for emitting a second spectrum of light only, or third source of light for emitting a third spectrum of light only; and an optics system including a single lens for receiving and transmitting at least one of: the first spectrum of light transmitted through the first portion; the second spectrum of light transmitted through the second portion; and the third spectrum of light transmitted through the third portion. The optical system includes a single color image sensor for receiving the at least one of the first, second, or third spectrums of light from the single lens and generating and transmitting data characterizing the at least one of the first, second, or third spectrums of light received from the single lens. The imaging system includes a memory element for storing computer executable instructions, and at least one processor configured to execute the computer executable instructions to generate, using the data, at least one of first, second, or third images of the first, second, or third portions, respectively. The first, second, and third spectrums of light are free of overlapping wavelengths amongst each other.

According to aspects illustrated herein, there is provided a method of imaging an infusion tube having a drip chamber including a first portion with a drip tube, a second portion with an exit port, and a third portion located between the first and second portions, including: storing, in a memory element, computer executable instructions; emitting at least two of first, second, or third spectrums of light from at least one light source; receiving and transmitting, using a single lens at least two of: the first spectrum of light transmitted through the first portion; the second spectrum of light transmitted through the second portion; or the third spectrum of light transmitted through the third portion; receiving, using a single image sensor, the at least two of the first, second, or third spectrums of light from the single lens; generating and transmitting, using the single image sensor data characterizing the at least two of the first, second, or third spectrums of light received from the single lens; and executing, using the at least one processor, the computer executable instructions to generate, using the data, at least two of first, second, or third images of the first, second, or third portions, respectively.

According to aspects illustrated herein, there is provided a method of imaging an infusion tube having a drip chamber including a first portion with a drip tube, a second portion with an exit port, and a third portion located between the first and second portions, including: storing computer executable instructions in a memory element; emitting, using a single light source, at least two of first, second, or third spectrums of light: receiving and transmitting, using a single lens at least two of: the first spectrum of light transmitted through the first portion; the second spectrum of light transmitted through the second portion; or the third spectrum of light transmitted through the third portion; receiving, using a single color image sensor, the at least two of the first, second, or third spectrums of light from the single lens; generating and transmitting, using a single color image sensor, data characterizing the at least two of the first, second, or third spectrums of light received from the single lens; and executing, using at least one processor, the computer executable instructions to generate, using the data, at least two of first, second, or third images of the first, second, or third portions, respectively.

According to aspects illustrated herein, there is provided a method of imaging an infusion tube having a drip chamber including a first portion with a drip tube, a second portion with an exit port, and a third portion located between the first and second portions, including: storing computer executable instructions in a memory element; and emitting at least one of a first spectrum of light only using a first light source, a second spectrum of light only using a second light source; or a third spectrum of light only using a third light source. The method includes: receiving and transmitting, using a single lens at least one of: the first spectrum of light transmitted through the first portion; the second spectrum of light transmitted through the second portion; or the third spectrum of light transmitted through the third portion; receiving, using a single color image sensor, the at least one of the first, second, or third spectrums of light from the single lens; generating and transmitting, using the single color image sensor, data characterizing the at least one of the first, second, or third spectrums of light received from the single lens; and executing, using at least one processor, the computer executable instructions to generate, using the data, at least one of first, second, or third images of the first, second, or third portions, respectively. The first, second, and third spectrums of light are free of overlapping wavelengths amongst each other.

DETAILED DESCRIPTION

FIG. 1is a schematic representation of definitions for an infusion pump.

FIG. 2is a schematic block representation of infusion pump100with optical imaging system102. Pump100includes specially programmed microprocessor104, drip chamber106for connection to output tube108, and drip tube110for connecting the drip chamber to a source of fluid112, for example, an IV bag. The drip tube includes end114disposed within the drip chamber. The imaging system includes illumination system118and optical system120. System118includes lighting element122for transmitting light through wall123of the drip chamber to or around drop124of the fluid suspended from the end of the drip tube, for example, one or both of the drip and end114are illuminated. System118also controls illumination properties of the light transmitted to the drop. System120receives, for example using optical sensor126, light transmitted through the drop, or through or around end114and transmits, to the microprocessor, data129regarding the received light. Pump100also includes pumping mechanism127. In one embodiment, the mechanism includes top and bottom flow restrictors and uses peristaltic actuators, such as rollers, to displace fluid through tube108.

FIGS. 3A through 3Fillustrate example embodiments of system118inFIG. 2. As shown inFIG. 3A, light rays128from a collimated illumination system are parallel. As shown inFIG. 3B, light rays130from a diffuse illumination system are emitted in a cone-shaped pattern from each light emitting point on an illumination plane. As shown inFIG. 3C, light rays132from illumination source122pass through telecentric lens134and are formed into ray bundles136. The rays in bundles136are very nearly parallel. The ray bundles provide sharp definition of image edges and minimize depth distortion As shown inFIG. 3D, a structured lighting element shapes illumination, for example, rays138, so as to control unwanted or stray light and to accentuate edges of an objecting being illuminated. A structured lighting element can include barrier139, disposed between an illumination source and an object being illuminated, for example, drop124, to shape the illumination, for example, by blocking or altering light emanating from the source.

FIG. 3Eillustrates the use of laser interference to project stripe patterns measure drop124. Illumination source122includes laser light sources187. Sources187project light patterns consisting of many stripes at once, or of arbitrary fringes. This technique enables the acquisition of a multitude of samples regarding an image of drop124, simultaneously. As seen from different viewpoints, the projected pattern appears geometrically distorted due to the surface shape of the object. In one embodiment, patterns of parallel stripes are used; however, it should be understood that other patterns can be used. The displacement of the stripes allows for an exact retrieval of the three dimensional (3D) coordinates of details on an object's surface, for example, the surface of drop124. Laser interference works with two wide planar fronts189from laser beams191. The interference of the fronts results in regular, equidistant line, or interference, patterns193. Different pattern sizes can be obtained by changing the angle between the beams. The method allows for the exact and easy generation of very fine patterns with unlimited depth of field.FIG. 3Eis a top view of pump100and sources187are shown disposed radially about axis195for drop tube110. However, it should be understood that other configurations of sources187with respect to the pump are possible, for example, parallel to axis195.

FIG. 3Fillustrates the use of projection lens196in system118. InFIG. 3F, system118illumination source transmits light197through lens196. Surface198of the lens is modified as known in the art, for example, etched or through deposition of chrome or other materials, to produce a pattern on the surface. Light197passing through the lens projects an image of the pattern on and about drop124. In one embodiment, projected pattern199is in the form of a constant-interval bar and space square wave, such as a Ronchi Ruling, or Ronchi grating.

The illumination source for a structured lighting element can be collimated, diffuse, or telecentric. Structured illumination can control unwanted or stray light and accentuate image edges. In one embodiment, the illumination system includes a telecentric lighting element. In one embodiment, the illumination system includes a structured lighting element.

Returning toFIG. 2, microprocessor104includes data processing segment140and data acquisition and control segment142. The pump also includes control panel144, for example, any graphical user interface known in the art. Output from the optical system, for example, data129from sensor126, is inputted to segment142. Panel144, or other operator input, is used to input a desired flow rate through the drip chamber, as well as other necessary data such as drug type and treatment information. Microprocessor104can be any microprocessor known in the art.

Pump100uses optical sensing of pendant drops, that is drops hanging from or suspended from end114, to measure fluid flow through the drip chamber to the output tube and to provide input to a closed-loop pump control process controlled by the microprocessor. Fluid from source112flows through drip tube to end114of the drip tube. The fluid forms drop124at end114and when conditions in the drip tube, discussed infra, are suitable, the drop falls from end114into fluid146in the drip chamber. In general, a pendant drop increases in volume in proportion to the outflow of fluid146from the drip chamber through tube108. That is, an increase in the volume of the pendant drop during a time frame is equal to the volume of fluid passing from the drip chamber to tube108in the time period. The preceding relationship is based on the following assumptions: the fluid from the source is not compressible; source112, the drip tube, the drip chamber, tube108, and a patient to whom tube108is connected are closed to outside atmosphere. Each measurement of the drop volume is processed to provide a fluid volume (or mass) measurement. Successive measurements of drop volume over known intervals of time are used by the microprocessor to calculate the flow rate of fluid through the system.

Thus, in one embodiment, operation of pumping mechanism127is controlled by the microprocessor using the desired set point for flow through the drip chamber and data regarding a measured flow rate of fluid through the drip chamber. For example, the microprocessor executes a feedback loop which compares the desired flow rate with the measured flow rate, and adjusts the pumping mechanism to correct any deviations between desired and measured flow rates.

FIGS. 4A through 4Care schematic representation of embodiments for optical system120. The embodiments shown inFIGS. 4A through 4Cform real, conjugate images, for example, of drop124on a focal plane array formed by sensor126.FIGS. 4A and 4Buse refractive optics, such as single lens148or combinations150of lenses, respectively.FIG. 4Cshows refractive optics, such as combination150of lenses, and reflective optics, such as fold mirror152. Lens148, combination150, and mirror152can be any lens, combination of lenses, or mirror known in the art. Combination150may include different lenses inFIGS. 4B and 4C.

Returning toFIG. 2, in one embodiment, optical sensor126is a focal plane array formed by any means known in the art, including, but not limited to a charge coupled device (CCD), a CMOS detector, or a hybrid imaging array such as InGaAs bonded to a CMOS readout integrated circuit. System120includes optics, such as lens148, focused on the location of drop124. It should be understood that other optics can be used in system120. In one embodiment, chamber106is substantially optically clear and system118directs light though the walls of the chamber to the optical system, for example, sensor126. The light can provide back or side illumination of the drop. In one embodiment, system102is configured such that drop124and the focal plane array are optical conjugates and the focal plane array records an actual image of the drop. The imaging system captures drop images at a rate sufficient to observe the growth and detachment of a single drop.

In one embodiment, pump100satisfies two key metrics with respect to imaging drop124. First, the frame rate (images per second) is sufficient to capture a sequence of images as the drop grows in size and detaches. Second, the exposure time (the amount of time the light is collected on the sensor for each specific image) is short enough to freeze the motion of the drop. Pump100generates images with clear edge definition, sufficient magnification (in terms of number of pixels across the drop), and a minimum number of artifacts such as glare.

In one embodiment, imaging system102and the microprocessor produce an accurate image of the drop that is then analyzed as described infra to determine the volume of the drop. Since the fluid drop has a uniform density, and any bubbles (occlusions) or entrainments are sufficiently small to be negligible, in one embodiment, only the outer surface of the drop is measured to calculate the volume of the drop. The preceding measurement is accomplished by imaging the drop with sufficient spatial resolution to accurately measure the boundary surface. A numeric integral over this boundary then provides the droplet volume.

FIGS. 5A through 5Cillustrate imaging processing definitions. In one embodiment, a reference/alignment frame and an image scale (pixels per mm) are established by locating end point114of the drip tube orifice, as shown inFIG. 5A. The end point has a known size and hence provides scale calibration. The end point also represents the top boundary of the drop, which is used in volume calculations described infra. In one embodiment, apex154of the drop (a point furthest from the fixed/reference point) is identified and used in the determination of the volume of the drop. For example, the optical system, for example, sensor126, receives the light transmitted into or through the drip tube and transmitting, to the microprocessor, data regarding the received light. In one embodiment, the microprocessor is for determining, using the data, a boundary of end point114and using the boundary of end point114as a reference point for determining a volume, shape, or location of the drop, as further described infra.

In one embodiment, as further described infra, the direction of gravity (gravity vector156) with respect to drop124is determined. A reference point, for example, the boundary of end point114, and the gravity vector are used to establish a reference frame for the image processing.

In one embodiment, volume of drop124is calculated by using the microprocessor to receive data129and generate an image of the drop from the data. The microprocessor locates an outer edge of the drop in the image to define boundary157of the drop. The microprocessor integrates an area enclosed by the boundary and calculates a volume of revolution for the drop with respect to axis159for the drop that intersects the end of the drip tube, assuming symmetry of the drop with respect to the axis.

The above calculation of the volume of drip124can be calculated using at least two broad approaches. The first approach, termed Boundary Constrained Volume and shown inFIG. 5B, uses the outer location of the drop image to calculate the total volume. Each horizontal row158of pixel data from the image has associated with it an outer left and right boundary. The area between these boundaries is treated as the two dimensional projection of a circular disk volume (the symmetric volume of rotation of the area). The drop image is integrated from end point114to the apex by summing the volume of each row. Boundary Constrained Volume obtains maximum resolution for each row of data.

The second approach is termed Fit Constrained Volume and is shown inFIG. 5C. That is, the volume of drop124is determined by fitting a parametric function to the boundary image of the drop and integrating the parametric function, again, assuming rotational symmetry. There are a number of possible fitting algorithms, as discussed below, but the result of any fit is a set of parameters to the assumed function that represents entire boundary157. Fit Constrained Volume smoothes out row detail.

In one embodiment, the microprocessor creates a plurality of temporally successive images of the drop from data129and calculates a respective volume for the drop in each successive image or calculates respective time periods between detachment of successive drops from the end of the drip tube. By temporally successive images, we mean a series of images taken over a time period in chronological order. The microprocessor calculates a rate of increase for the volume of the drop using the respective volumes or the respective time periods. As noted above, flow out of the drip tube is substantially equal to the increase in the volume of the drop; therefore, the time periods between drops detaching from the end of the drip tube can be correlated to the volume increases of the successive drops. For example, in one embodiment, the microprocessor calculates a respective volume for the drop in each successive image, for example, using operations described infra and supra; calculates changes in the respective volumes; and calculates a flow rate of fluid to the output tube based on the changes in the respective volumes. In one embodiment, the microprocessor controls mechanism127to match the calculated flow rate with a desired flow rate, for example, stored in the microprocessor.

In one embodiment, the microprocessor is for generating a free flow alarm or an out of bound condition alarm when the rate of increase for the volume of the drops exceeds a predetermined value, for example, stored in the microprocessor. In one embodiment, the microprocessor is for operating mechanism127to shut off flow to the output tube when the free flow alarm or the out of bound condition alarm is generated. In one embodiment the microprocessor generates a downstream occlusion alarm when the rate of increase of the volume of the drop is less than a predetermined value. In one embodiment, the microprocessor determines that a drop is absent from the end of the drip tube for a specified period of time and generates an empty bag alarm or an air-in-line alarm.

In one embodiment, the pump includes processor163used to operate mechanism127to shut off flow to the output tube when the free flow alarm or the out of bound condition alarm is generated. That is, as a safety and redundancy factor, a second microprocessor is used in the pump.

The drop is initially hanging from a fixed point in the drip chamber, for example, end114. In one embodiment, the microprocessor is for identifying when the drop detaches from the fixed point in the drip chamber as a means of determining when the drop has reached maximum volume. The microprocessor makes the preceding identification by creating a plurality of temporally successive images of the drop and analyzing these images. By temporally successive images, we mean a series of images taken over a time period in chronological order.

In one embodiment, the microprocessor identifies, in each successive image, a respective point in the boundary, for example, apex154, and determines a distance of each respective point from end114. The microprocessor then identifies two successive images of the drop in which the distance, noted above, in the second image in the succession is less than the distance in the first image in the succession. This decrease of the distance indicates that the drop detached from the fixed point in the interval between the first and second images, which further indicates that the drop reached a maximum size in the first image. The microprocessor calculates the volume of the drop using the first image.

FIG. 6illustrates image160of drop124including circle162at least partly included within outer boundary164of the drop.FIG. 6illustrates a specific example of the Fit Constrained Volume approach. In one embodiment, the microprocessor identifies respective circles162within each temporally successive image. The circles are partially defined by a respective outer boundaries164of the temporally successive images. The microprocessor identifies a respective location, with respect to the fixed point in the drip chamber, for each respective circle and calculates a volume of the drop from the data and using the respective circles.

In one embodiment, identifying the respective location for said each respective circle includes identifying the image corresponding to the largest size of the drop, for example, the last image before the drop detaches from the end point of the drip tube. For example, the microprocessor identifies a respective point on each respective circle at a furthest distance from the fixed point in the drip chamber, for example, end point114. The microprocessor then determines which of the respective points is furthest from the fixed point and identifies an image including the respective point furthest from the fixed point. That is, the microprocessor identifies the largest drop by identifying the drop having the largest circle. In one embodiment, the largest drop is identified by determining a first image in which the distance of the apex from the fixed point decreases with respect to the distance of the apex from the fixed point for a second image immediately preceding the first image. This decrease indicates that the drop detached from the fixed point in the interval between the first and second images, which further indicates that the drop reached a maximum size in the first image. The microprocessor calculates the volume of the drop using the image including the respective point furthest from the fixed point.

In one embodiment, the microprocessor identifies the respective outer boundaries for each of the temporal images such that each outer boundary includes a respective edge of the drop furthest from the fixed point in the drip chamber and the respective circle includes the respective edge. That is, the microprocessor aligns the circles described supra with the actual edges of the drops such that the points of the circles furthest from the fixed point, for example, end114, are part of the edge of the drop. In one embodiment, the microprocessor identifies respective circular arcs corresponding to the respective edges and including the respective circular arcs in the respective circles.

In one embodiment, identifying the image corresponding to the largest size of the drop, for example, the last image before the drop detaches from the end point of the drip tube, includes using the center points of the circles. For example, the microprocessor calculates respective center points166for the circles and calculates the positions of the center points with respect to the fixed point, for example, end point114. The microprocessor then determines which of the center points is furthest from the fixed point and identifies an image including the center point furthest from the fixed point. That is, the microprocessor identifies the largest drop by identifying the drop having the largest circle. The microprocessor calculates the volume of the drop using the image including the center point furthest from the fixed point.

FIG. 7is a flow chart illustrating operation of pump100with an optical imaging system.FIG. 7illustrates an example algorithm usable by pump100. It should be understood that other algorithms are usable by the pump. The image of drop124is filtered and thresholded to create a binary image. Filter operations can include median filtering (to remove isolated glare), background and image uniformity correction (to remove noise sources due to dark noise, read noise, pixel non-uniformity, and illumination non-uniformity), and edge definition (using techniques such as convolution or unsharp masking). The resulting images are thresholded to yield binary images. A binary image consists of values that are either black or white, with no intermediate grayscale values. The images are also processed (in parallel with the above operations) to find the reference location, for example, end point114, using techniques such as feature detection, pattern matching, or transform techniques such as the Radon transform. The end point location is used to form an image mask. A mask isolates a region of an image for further processing. Use of a mask increases computational speed, as well as eliminates artifact information from being further processed.

In one embodiment, the binarized, masked images are then processed row-by-row to find the extreme right- and left-boundaries. This boundary-constrained fit is one estimate of the drop edge shape. In one embodiment, the images are also processed using a fit-constrained algorithm. Such an algorithm applies constraints based on assumptions about the drop shape as discussed supra and infra. The constraints are used in a non-linear least squares optimization scheme to minimize the error between the parameterized constraint function(s) and the set of binarized edge images.

The two different edge approximations are provided to an Edge Estimator algorithm that compares fit-constrained images to boundary-constrained images. In the simplest instantiation, the images are compared row-by-row. The boundary-constrained images are considered to be the “correct” result unless they deviates from the fit-constrained images by more than a certain parameter (this parameter is adjusted during calibration). If the deviation is too large, the value from the fit-constrained image is used to replace that of the boundary-constrained image for that row. The above is intended to illustrate the concept behind the estimator. In actual use, more sophisticated algorithms are used to simultaneously optimize the difference between the two initial estimates. An example of such an algorithm is a Kalman filter, but other algorithms familiar to those skilled in the art may also be utilized.

The output from the Edge Estimator also provides the location of the apex of the drop, which is for example, used to calculate the time-dependent gravity vector. This operation requires access to prior estimates of the apex value (to calculate the change), and hence a number of prior values are stored in a buffer. The gravity vector is required for some of the parametric fit functions that are used in the fit-constrained edge estimation algorithms. Hence, the gravity vector is used in a feedback loop for the edge fit algorithms.

FIGS. 8A and 8Bare schematic details for pump100implementing an operation for determining gravity vector156. In one embodiment, system118illuminates end point114and drop124and the optical system, for example, sensor126, receives light emanating from the end point and light emanating from the drop and transmits data129regarding the received light. The microprocessor generates, using the data, respective images of the drop and the end of the drip tube and locates an apex of the drop, the apex being a portion of the drop at a furthest distance from the end of the drip tube. The microprocessor determines, using the location of the apex, an orientation of the drop with respect to the end of the drip tube and calculates, using the orientation of the drop with respect to the end of the drip tube, an orientation of the drip chamber. In one embodiment, the microprocessor compares the orientation of the drip chamber to a set point, for example, a certain orientation with respect to plumb stored in the microprocessor, and generates an out of bound condition alarm when the orientation equals the set point or varies from the set point by a specified amount. For example, if the drip chamber is too far out of plumb, operation of pump100may be compromised and the alarm is generated.

For example, inFIG. 8Aline168for the actual orientation of the drop and axis170for the drip chamber are co-linear, Since the drop must necessarily align with the forces of gravity (is plumb), the drip chamber is in a plumb orientation inFIG. 8A. Also, line168is aligned with gravity vector156. InFIG. 8B, lines168and170are not co-linear and the drip chamber is not plumb. Thus, in one embodiment, the microprocessor generates lines168and170and compares the respective locations or orientation of the lines. That is, the microprocessor calculates the orientation of the drip chamber with respect to the gravity vector. In one embodiment, when data129is used to generate respective images over a period of time (temporally sequential images), the gravity vector is determined by measuring in the images of the end of the drip tube and the drop, the location of the apex of the pendant drop as it grows over time and tracking the time-dependent directional change of the apexes over a series of these measurements. In one embodiment, the boundary of end114is calculated as described supra and the boundary is used as reference plane for calculating the orientation of the drop and/or the drip chamber.

In one embodiment, the illumination system controls illumination properties of the light illuminating the end of the drip tube and the drop and the microprocessor: identifies respective boundaries of the end of the drip tube and the drop from the respective images; fits a parametric function to the respective boundaries; and integrating the parametric function to obtain a volume of the drop, for example, as described above.

In one embodiment, the end point location, gravity vector, and optimal edge estimate are input to a volume calculation routine that integrates the edge image using the “circular disk” assumption discussed above. The location of the end of the drip tube is used to determine the upper limit of integration, while the gravity vector is used to determine the direction of the horizontal (at right angles to the gravity vector). These end and gravity data values are provided along with the volume as output from the algorithm. In one embodiment, the algorithm also passes out the parameters of the edge fit, as well as statistical data such as fit variances. In one embodiment, the preceding information is used in the digital signal processing chain discussed below.

A number of methods can be used to fit a constraint to the measured image. In one embodiment, a “pendant drop” approach, involves solving the Laplace-Young equation (LYE) for surface tension. A drop hanging from a contact point (the end point) has a shape that is controlled by the balance of surface tension (related to viscosity) and gravity. The assumption is only strictly valid when the drop is in equilibrium; oscillations (due to vibration or pressure fluctuations) will distort the drop shape from the Laplace-Young prediction. However, small oscillations will not cause the fit to fail; in fact, the deviation from a fit is itself a good indicator of the presence of such oscillations.

In one embodiment, a Circular Hough Transform (CHT) is used on the image to identify the component of the image that represents the curved bottom of the drop. While not strictly a “fit”, the CHT provides a parametric representation of the drop that is characterized by the value and origin of the radius of a circle. The CHT algorithm is representative of a constraint that is determined or applied in a mathematical transform space of the image. Other widely-used transforms, familiar to those skilled in the art, are the Fourier and wavelet transforms, as well as the Radon transform.

The parametric fitting procedures described above apply strong constraints on the possible location of the edge of the drop. Along with the assumption of continuity (a fluid edge cannot deviate from its neighbors over sufficiently short distances), and the requirement that the drop edge terminate at the drip tube orifice, the procedures are used to augment and correct the boundary-constrained image, as discussed above. Other fitting procedures work similarly to those discussed herein.

FIGS. 9A and 9Bare schematic details of pump100using light injection. Drip tube110, drip chamber106, tube108, drop124, imaging system120, and sensor126are as described forFIG. 2. Illumination system118includes illumination source172for transmitting, or injecting, light174into the drip tube. The light reflects off a plurality of portions of internally facing surface176of the drip tube and the reflected light is transmitted through the end point114of the drip tube into interior177of drop124such that the interior is uniformly illuminated. The optical system receives light178transmitted from the interior of the drop and transmits, to the computer processor, data regarding the received light. The data regarding the received light can be operated upon using any of the operations noted supra. For example, in one embodiment, the illumination system is for controlling illumination properties of the light transmitted to the drop, and the optical system is for receiving light from the drop. The microprocessor is for: generating an image from the data, the image including a boundary of the drop; fitting a parametric function to the boundary of the drop; and integrating the parametric function to obtain a volume of the drop.

Thus, light174is formed into a beam, which is injected into the transparent drip tube so as to undergo significant internal reflection (i.e., equal to or greater than the so-called “critical angle”). The cylindrical bore of the tube causes the internal reflections to diverge inside the tube (filling the bore of the tube), while imperfections in the tube surface introduce light scattering. The result is that the drop is illuminated internally. Under these conditions the imaging optics in system120receive only light that is scattered from the drop surface (there is no direct ray path for the light to reach the lens). In addition to a high contrast edge image, this approach enables the use of a very compact illumination element.

FIG. 10Ais a schematic detail of pump100with a meniscus detection arrangement. Drip tube110, drip chamber106, tube108, and fluid146are as described forFIG. 2. Imaging system102includes light source, for example, a laser, for transmitting light182at an acute angle with respect to longitudinal axis184for the drip chamber, into the drip chamber such that the light reflects, at the acute angle, off a surface186of fluid pooled within the drip chamber. System102also includes sensor, or position sensitive detector,188for receiving reflected light182and transmitting, to the computer processor, data regarding the received light. The microprocessor is for calculating a position of surface186using the data regarding the received light.

The location on sensor188receiving light182depends on the location of surface186. Levels190A and190B show two possible levels for fluid146and hence, two possible locations for surface186. As seen inFIG. 10B, light182A and182B reflecting from levels190A and190B, respectively, strike different portions of sensor188. The microprocessor uses the difference between the locations on sensor188to determine the level of fluid146, that is, the meniscus, in the drip chamber. Sensor188can be any positional sensitive detector known in the art, for example, a segmented sensor or a lateral sensor. In one embodiment, the microprocessor generates an empty bag alarm or an air-in-line alarm for an instance in which the light transmitted from light source188is not received by the optical system, for example, the drip chamber is empty or level186is so low that light182does not strike fluid146.

A segmented positional sensitive detector includes multiple active areas, for example, four active areas, or quadrants, separated by a small gap or dead region. When a symmetrical light spot is equally incident on all the quadrant, the device generates four equal currents and the spot is said to be located on the device's electrical center. As the spot translates across the active area, the current output for each segment can be used to calculate the position of the spot. A lateral positional sensitive detector includes a single active element in which the photodiode surface resistance is used to determine position. Accurate position information is obtained independent of the light spot intensity profile, symmetry or size. The device response is uniform across the detector aperture, with no dead space.

FIG. 10Bis a schematic detail of pump100with a meniscus detection arrangement. In one embodiment, imaging system102includes mirror192on the opposite side of the drip tube to reflect light182back through the drip tube and beam splitter194to direct the reflected light to sensor188. This configuration enables placement of all the electronics for the optical components on the same side of the tube.

The following provides further detail regarding meniscus level measurement. The drip chamber remains partially filled with fluid at all times during operation. The air trapped in the drip chamber is in pressure equilibrium with the fluid above and below it. The difference in pressure across the air gap drives fluid out of the bottom of the drip chamber and through downstream tubing108. Fluid enters and leaves the drip tube chamber continuously as the drop grows in volume, and hence the meniscus level of the fluid remains nearly constant. However, changes in the meniscus level can occur for several reasons: transient changes may occur when a drop detaches and falls into the fluid below; or fluctuations may occur due to pressure oscillations in the fluid (due to pump vibration, motion of the tubing set, or motion of the patient). These transient changes will fluctuate around a mean meniscus value, and hence do not indicate changes in flow rate over times long compared to the characteristic fluctuation times.

Variations that change the mean meniscus level over longer times may occur due to changes in the external pressure environment (e.g., in a traveling vehicle or aircraft), changes in backpressure arising from medical issues with the patient, or due to occlusions or other malfunctions in the pumping process. These long-term meniscus level changes represent a concomitant change in the overall flow rate, and may be used to provide a refinement to the flow measurements described supra. Hence, it may be desired to monitor the level of the meniscus during the infusion, and to use the information derived therein as an indicator of operational problems with the infusion system, or as an adjunct to the primary optical flow measurement.

The method described above for measuring the level of fluid146uses the reflection of a light beam from the top surface of the fluid in the drip chamber. The axis of the reflected beam is shifted (deflected) laterally as the fluid level changes, for example, as shown by light182A and182B. The amount of deflection depends only on the fluid level change, and on the incident angle of the beam. Although a laser light source is shown in the figure, the technique is compatible with any light beam. Further, although the beam is shown freely propagating, the system may also incorporate lens elements to control the beam.

In one embodiment (not shown), sensor126(the imaging focal plane array) is used both for imaging drop124and measuring the meniscus of fluid146via beam splitters and other simple optics. Sensor126can be shared in at least two ways: a portion of the sensor that is not used for pendant drop imaging can simultaneously record the deflected beam; or illumination system118for pendant drop imaging and meniscus level measurement can be alternated in time, such that the sensor alternately records the drop image and the deflected beam image. For example, pump100can combine the imaging systems102shown inFIGS. 2 and 10A/10B or shown inFIGS. 2 and 9A.

Thus, in one embodiment, system102includes a first light source, such as light source172for transmitting light into the drip tube such that the light reflects off an internally facing surface of the drip tube, and the reflected light is transmitted through the end of the drip tube into an interior of a drop of the IV fluid hanging from the first end of the drip tube. System102also includes a second light source, such as light source188, transmitting light, at an acute angle with respect to a longitudinal axis for the drip chamber, into the drip chamber such that the light reflects, at the acute angle, off a surface for IV fluid disposed within the drip chamber. Optical sensor126is for: receiving the reflected light transmitted from the interior of the drop; receiving the reflected light from the second light source; and transmitting, to the computer processor, data regarding the received light from the first and second light sources. The microprocessor is for calculating a volume of the drop using the data regarding the light received from the first light source, and calculating a position of the surface of the using the data regarding the light received from the second light source, as described supra.

FIG. 11is a schematic block representation of pump assemblies200A and200B with respective optical imaging system in a primary and secondary configuration. The assemblies include the components for pump100described supra, with the exception of the processor and control panel. In general, the description above regarding the operation of pump100is applicable to the operation of assemblies200A and200B. Assembly200A is connected to primary fluid source112A. Pump200B is connected to primary fluid source112B. Sources112A and112B are arranged in a primary/secondary infusion configuration. For example, a primary medication in source112A is administrated in coordination with a secondary medication in source112B. As is known in the art, in a primary/secondary configuration, the medication in the secondary source is infused before the medication in the primary source. Tubings108A and108B from pump mechanisms127A and127B, respectively, are connected to common tubing202.

In one embodiment, a single processor and control panel, for example, processor104and panel144are used for assemblies200A and200B. The processor operates assembly200B according to appropriate protocols until the regime for the fluid in source112B is completed. Then, the processor automatically deactivates assembly200B as required and begins the infusion of the fluid in source112A. In one embodiment (not shown), each assembly has a separate processor and control panel or each assembly has a separate processor and a common control panel.

FIG. 12is a top-level block diagram illustrating operation of pump100with an optical imaging system. In one embodiment, the volume measurement, and fit metrics if applicable, described above are fed into a digital signal processing algorithm that calculates the flow rate and provides feedback to the pump control system. Plant210includes source112, the drip chamber, the drip tube, and pump mechanism127. The microprocessor outputs the Volume and Fit Metrics212, which are filtered by digital filter214in a portion of the microprocessor to provide measured flow rate216. The measured flow rate is compared with the desired flow rate, for example, input into the microprocessor via panel144, closing the feedback loop for pump100.

FIG. 13is a block diagram illustrating example signal processing and feedback control for pump100with an optical imaging system. Mechanism127includes drive218and motor220. Imaging data from system102is processed by image processing block222to generate a Measured Drop Volume, and the results are input to filter block224. The output of the filter block is the Measured Flow Rate. The Measured Flow Rate is compared to the Desired Flow Rate by comparator226, providing the Error Flow Rate (error estimate). The Error Flow Rate feeds into a staged series of PID (Proportional, Integral, Derivative) control algorithms228. Each PID block operates on a successively faster time scale. Block228A controls the flow rate, block228B controls the pump motor speed, and block228C controls the pump motor current. The speed control incorporates feedback from motor position encoder230. The current control incorporates feedback from a motor current sensor in motor220.

FIG. 14is a block diagram illustrating example digital filtering in pump100with an optical imaging system. Filter232can be any filter known in the art, for example, the general class of FIR/IIR filters known to those skilled in the art. A simple example is an FIR filter that implements a time average over a number of samples.

FIG. 15is a schematic representation of example spatial filtering in pump100with an optical imaging system. The goal of high resolution and edge definition for images of drop124are attained by illumination techniques, optical techniques, or both, for example, as described supra. In one embodiment, spatial filtering techniques are used in the optics for system120. For example, mask240at the back focal plane of imaging system102modifies (via optical Fourier transform) the image generated by the optical system, for example, sensor126. A DC block filter is shown inFIG. 15. This filter blocks the central cone of the transmitted light and enhances edge images (associated with scattered light).

In one embodiment, the sensitivity of sensor126is matched to the illumination spectrum of the light source in system118. In one embodiment, sensor126is a low-cost visible light sensor (400-1000 nm wavelength) and source122generates light that is outside the range of human visual perception (i.e., 800-1000 nm). In this case the operator will not be distracted by the bright illumination source.

It should be understood that pump100can be any pump mechanism or pump application known in the art and is not limited to only IV infusion pump applications. In the case of a gravity-fed system, the pumping mechanism can be replaced by a valve or flow restrictor, and still be compatible with the configurations and operations described supra.

FIG. 16is a schematic representation of optical imaging system300with multiple imaging channel optical sensing. In an example embodiment, system300is used with infusion tube302including drip chamber304. Drip chamber304includes portion306with drip tube308, portion310including exit port312, and portion314between portions306and310. Output tube316can be connected to exit port312for flowing fluid out of drip chamber304. Drip tube308is for connection to source of fluid317, for example, medication bag317. System300includes at least one light source318for emitting spectrums S1, S2, and S3of light, and optical system319.

Light source318can be any light source known in the art, including, but not limited to a light-emitting diode (LED), an array of LEDs, a laser diode, an incandescent lamp, or a fluorescent lamp.

By “characterize” we mean that the respective data describes, or quantifies, the spectrum of light, for example, providing parameters enabling generation of an image using the respective data. By “emitting light” we mean that the element in questions generates the light. By “transmitted by” we mean passing light through the element in question, for example, light emitted by light source318passes through portions306,310, and314.

In an example embodiment, sensor322is a color image sensor. In an example embodiment, light source318is a single light source.

In an example embodiment, portion306includes drop338pendant from drip tube308and image332includes an image of drop338. Processor330is configured to execute instructions331to determine a volume of pendant drop338using image332. The volume can be used in control schemes to regulate flow of fluid through infusion tube302.

In an example embodiment, portion314includes meniscus342for fluid in drip chamber304and image336includes an image of meniscus342. Processor330is configured to execute instructions331to determine a position of meniscus342using image336. The position can be used in control and alarm schemes to regulate flow of fluid through infusion tube302. In an example embodiment, air bubble344is present in portion310and processor330is configured to execute instructions331to determine a volume of air bubble344using image334. The volume can be used in alarm schemes to ensure safe operation of infusion tube302.

In an example embodiment, light source318emits red, blue, and green spectrum light. In an example embodiment, S1T consists of one of the red, blue, or green spectrum light, S2T consists of one of the red, blue, or green spectrum light not included in S1T, and S3T consists of one of the red, blue, or green spectrums of light not included in S1T or S2T. Thus each of S1T, S2T, and S3T consists of one of red, blue, or green light not included in the other of S1T, S2T, and S3T. That is, each of S1T, S2T, and S3T is different from the others. By “red spectrum light” we mean light including wavelengths between about 610 nm and 675 nm, with peak intensity at about 625 nm. By “blue spectrum light” we mean light including wavelengths between about 410 nm and 480 nm, with peak intensity at about 470 nm. By “green spectrum light” we mean light including wavelengths between about 500 nm and 575 nm, with peak intensity at about 525 nm. Thus, the respective spectrums for red, blue, and green light do not have overlapping wavelengths.

In an example embodiment, system300includes mirror346for reflecting one only of S1T, S2T, and S3T. For example, mirror346A reflects S1T. In an example embodiment, system300includes mirror346A for reflecting one only of S1T, S2T, or S3T, and mirror346B for reflecting another only of S1T, S2T, or S3T, for example, S3T. In an example embodiment, system300includes beam combiner348A for reflecting two only of S1T, S2T, or S3T. For example, inFIG. 16, beam combiner348A reflects S1T and S3T and transmits S2T.

The following provides further detail regardingFIG. 16. As described below, various filtering operations are used to generate S1T, S2T, and S3T. Mirror346A receives the combined red, blue, and green spectrums emitted by source318and transmitted by portion306of drip chamber304, but reflects only spectrum S1T. Mirror346B receives the combined red, blue, and green spectrums emitted by source318and transmitted by portion310of output tube316, but reflects only spectrum S3T. Thus, mirrors346A and346B are color-filtering.

In an example embodiment, sensor322is not monochrome, that is, sensor322is a color image sensor. Beam combiner348A transmits only spectrum S2T emitted by source318and transmitted by portion314of drip chamber304. Specifically, beam combiner348A receives the combined red, blue, and green spectrums emitted by source318and transmitted by portion314of drip chamber304, but only transmits spectrum S2T. The beam combiner also reflects spectrum SiT reflected by mirror346A and spectrum S3T reflected by mirror346B. Note that the reflecting operations of beam combiner348A can be implemented using broad-band reflection, since mirrors346A and346B have filtered out spectrums S2T and S3T and spectrums S1T and S2T, respectively.

FIG. 17is a schematic representation of optical imaging system400with multiple imaging channel optical sensing. The discussion regarding system300is applicable to pump400except as follows. In an example embodiment: optics system319includes a mirror for transmitting to one of portions306,310, or314one only of S1, S2, or S3; or optics system319includes a mirror for reflecting to one of portions306,310, or314, one only of S1, S2, or S3. For example: mirror346C transmits S1to portion306and reflects S2and S3; mirror346D transmits S3and reflects S2to portion314; and mirror346E reflects S3to portion310. In an example embodiment, mirror346E is a broad-band reflecting mirror.

Mirror346F is for reflecting spectrum S1T transmitted by portion306of drip chamber304to beam combiner348A. In an example embodiment, mirror346F is a broad-band reflecting mirror. Mirror346G is for reflecting spectrum S3T transmitted by portion310of drip chamber304to beam combiner348A. In an example embodiment, mirror346G is a broad-band reflecting mirror. Since the light entering beam combiner348A has been separated into discrete spectrums, for example, light from mirror346G is only spectrum S2T, broad-band transmitting and reflecting operations can be used in beam combiner348A.

FIG. 18is a schematic representation of optical imaging system500with multiple imaging channel optical sensing. The respective discussions regarding systems300and400are applicable to system500except as follows. In an example embodiment, optical system319replaces a beam combiner with mirrors346H and346I. Mirror346H transmits S1T reflected by mirror346F and reflects S2T (from mirror346D). Mirror346I transmits S3T (from mirror346E) and reflects S1T (transmitted by mirror346H) and S2T (reflected by mirror346H).

InFIG. 16, length L1of light source318must be sufficient to span portions306,310, and314, since light source318must emit light directly through portions306,310, and314. However, inFIGS. 17 and 18length L1of light source318is considerably less, for example, equal only to length L2of portion306. InFIGS. 17 and 18, light source318is emitting light directly through portion306; however, combinations of mirrors are used to reflect light to portions310and314. Thus, a smaller and less expensive device can be used for light source318inFIGS. 17 and 18.

FIG. 19is a schematic representation of optical imaging system600with multiple imaging channel optical sensing. The discussion regarding system300is applicable to system600except as follows. System600includes three light sources: light source318A for emitting only spectrum S1, light source318B for emitting only spectrum S2, and light source318C for emitting only spectrum S3. Optical system319includes mirror346J for reflecting S1T and mirror346K for reflecting S3T. Beam combiner348B transmits S2T and reflects S1T and S3T. In an example embodiment, one or both of mirrors346J and346K are broad-band reflecting mirrors. In an example embodiment, beam combiner348B has broad-band transmitting and reflecting functionality.

In respective example embodiments for system300,400,500, and600, two-channel imaging is performed for only two of portions306,310, or314and imaging is not performed on the remaining portion306,310, or314.

FIG. 20is a schematic representation of optical imaging system700with two-channel optical imaging and a single light source. In system700, chromatic multiplexing is implemented for only two of portions306,310, or314. System700can use system400as a starting point. The following describes differences between systems400and700as shown. InFIG. 20, two-channel optical imaging is implemented for portions306and314. Mirrors346E and346G are removed. Mirror346D no longer is required to transmit S3. Beam combiner348A is no longer required to reflect S3T. Otherwise, the operations regarding portions306and314are the same as described forFIG. 17. In an example embodiment, imaging of portion310is implemented by adding lens702to receive light S1T/S2T/S3T transmitted through portion310from light source318. Lens702transmits S1T/S2T/S3T to image sensor704, which generates data326. Processor330generates image334from data326. Image sensor704can be monochromatic, since chromatic multiplexing is not being implemented for portion310.

Other combinations of two-channel optical sensing are possible for system700as is apparent to one skilled in the art. For example, mirror346D can be removed such that two-channel optical sensing is performed for portions306and310only. Operations as described for portions306and310forFIG. 17are substantially the same. Lens702receives S1T/S2T/S3T transmitted by portion314and transmits S1T/S2T/S3T to image sensor704, which generates data328. Processor330generates image336from data328. Image sensor704can be monochromatic. For example, mirror346F can be removed such that two-channel optical sensing is performed for portions310and314only. Operations as described for portions310and314forFIG. 17are substantially the same. Lens702receives S1T/S2T/S3T transmitted by portion306and transmits S1T/S2T/S3T to image sensor704, which generates data324. Processor330generates image332from data324. Image sensor704can be monochromatic. It should be understood that other configurations of components in system400are possible to implement two-channel optical imaging. In an example embodiment, two-channel imaging is performed for only two of portions306,310, or314and imaging is not performed on the remaining portion306,310, or314. That is, a second lens and image sensor are not employed to image the remaining portion306,310, or314.

System300can be modified for two-channel operation as is apparent to one skilled in the art. For example, two-channel operation can be implemented for portions306and314only by removing mirror346B. Operations as described for portions306and314forFIG. 16are substantially the same. S1T/S2T/S3T from portion310is received by a second lens (not shown) and transmitted to a second image sensor (not shown) that can be monochromatic. The second sensor generates data326for generating image334. For example, two-channel operation can be implemented for portions310and314only by removing mirror346A. Operations as described for portions310and314forFIG. 16are substantially the same. S1T/S2T/S3T from portion306is received by a second lens (not shown) and transmitted to a second image sensor (not shown) that can be monochromatic. The second sensor generates data324for generating image332. For example, two-channel operation can be implemented for portions306and310only. Operations as described for portions306and310forFIG. 16are substantially the same. S1T/S2T/S3T from portion314is received by a second lens (not shown) and transmitted to a second image sensor (not shown) that can be monochromatic. The second sensor generates data328for generating image336. It should be understood that other configurations of components in system300are possible to implement two-channel optical imaging. In an example embodiment, two-channel imaging is performed for only two of portions306,310, or314and imaging is not performed on the remaining portion306,310, or314. That is, a second lens and image sensor are not employed to image the remaining portion306,310, or314.

System500can be modified for two-channel operation as is apparent to one skilled in the art. For example, to implement two-channel operation for portions306and314only, mirror346E can removed. Operations as described for portions306and314forFIG. 18are substantially the same. S1T/S2T/S3T from portion310is received by a second lens (not shown) and transmitted a second image sensor (not shown) that can be monochromatic. The second sensor generates data326for generating image334. For example, to implement two-channel operation for portions310and314only, mirror346F can removed. Operations as described for portions310and314forFIG. 18are substantially the same. S1T/S2T/S3T from portion306is received by a second lens (not shown) and transmitted a second image sensor (not shown) that can be monochromatic. The second sensor generates data324for generating image332. For example, to implement two-channel operation for portions306and310only, mirrors346D and346H can removed. Operations as described for portions306and310forFIG. 18are substantially the same. S1T/S2T/S3T from portion314is received by a second lens (not shown) and transmitted a second image sensor (not shown) that can be monochromatic. The second sensor generates data328for generating image336. It should be understood that other configurations of components in system500are possible to implement two-channel optical imaging. In an example embodiment, two-channel imaging is performed for only two of portions306,310, or314and imaging is not performed on the remaining portion306,310, or314. That is, a second lens and image sensor are not employed to image the remaining portion306,310, or314.

System600can be modified for two-channel operation as is apparent to one skilled in the art. For example, to implement two-channel operation for portions306and314only, mirror346K can removed. Operations as described for portions306and314forFIG. 19are substantially the same. S3T from portion310is received by a second lens (not shown) and transmitted a second image sensor (not shown) that can be monochromatic. Light source318C can be broadband (emit S1/S2/S3). The second sensor generates data326for generating image334. For example, to implement two-channel operation for portions310and314only, mirror346J can removed. Operations as described for portions310and314forFIG. 19are substantially the same. SIT from portion306is received by a second lens (not shown) and transmitted a second image sensor (not shown) that can be monochromatic. Light source318A can be broadband (emit S1/S2/S3). The second sensor generates data324for generating image332. For example, to implement two-channel operation for portions306and310only, S2T from portion314is received by a second lens (not shown) and transmitted a second image sensor (not shown) that can be monochromatic. Light source318B can be broadband (emit S1/S2/S3). The second sensor generates data328for generating image336. Operations as described for portions306and310forFIG. 19are substantially the same. It should be understood that other configurations of components in system600are possible to implement two-channel optical imaging. In an example embodiment, two-channel imaging is performed for only two of portions306,310, or314and imaging is not performed on the remaining portion306,310, or314. That is, a second lens and image sensor are not employed to image the remaining portion306,310, or314.

For the sake of brevity, portions of the following discussion are directed to system300inFIG. 16; however, it should be understood that the discussion is applicable toFIGS. 17 through 19as well. Further, the following discussion is directed to embodiments in which multiple channel optical sensing is implemented for all three of portions306,310, and314. However, it should be understood that the discussion is applicable to the two-channel embodiments discussed above. Using a single lens, such as lens320, and image sensor, such as sensor322, in place of three lens and sensors, reduces cost and complexity of system300. All three spectrums S1, S2, and S3, transmitted by lens320are received simultaneously by single image sensor322. However, if sensor322is a monochrome sensor, conventional signal processing cannot be used to generate images332,334, and346. For example, a monochrome sensor cannot distinguish among the red, blue, and green and cannot use conventional signal processing to separate spectrums S1T, S2T, and S3T to generate images332,334, and346. Advantageously, system300uses a color imaging sensor for sensor322, which is able to distinguish among spectrums S1T, S2T, and S3T.

Since a single, separate, respective color from the red, blue, and green spectrums is used for each of spectrums S1T, S2T, and S3T, imager322is able to transmit data324,326, and328for single respective spectrums and hence, a single respective image of each of portions306,310, or314can be generated using conventional signal processing operations. For example, spectrums S1T, S2T, and S3T can consist of red, blue, and green spectrum light, respectively. The red-responsive pixels of the sensor pick up spectrum S1T, the blue-responsive pixels of the sensor pick up spectrum S2T, and the green-responsive pixels of the sensor pick up spectrum S3T.

Thus, the red-responsive pixels record an image of drop338, the blue-responsive pixels record an image of meniscus342, and the green-responsive pixels record an image of portion310. Thus, each group of responsive pixels (for example, the red-responsive pixels) remain unresponsive to, in essence filtering out, images from the other images corresponding to the remaining groups of responsive pixels (for example, the blue and green-responsive pixels). Thus, there is no overlap of spectrums or images included in data transmitted to processor330and conventional signal processing can be used to generate images332,334, and346.

The use of broad-band reflecting mirrors/reflecting operations rather than color filtering reflecting and transmitting can reduce the cost of respective optics systems319inFIGS. 17 through 19.

In an example embodiment (not shown), a single lens, such as lens320, and a single monochrome image sensor are used in a time multiplexing arrangement in an infusion pump. For example, usingFIG. 19as a reference, each of light sources318A/B/C emits the same spectrum of light. The emitted light is transmitted through portions of an infusion tube, such as infusion tube302, analogous to portions306,310, and314described supra. Via an arrangement similar to mirrors346A/346B and beam combiner348A, the light, transmitted through the analogous portions, is transmitted to the single lens, which transmits the light to a processor, such as processor330. As noted above, a monochrome sensor cannot distinguish, using conventional signal processing, three simultaneously received images. However, in the example embodiment, the three light sources are sequentially energized such that only one light source is energized per image frame of the image sensor. For example, in a first frame, the light source emitting light transmitted through the portion analogous to portion306is energized, in the next frame, the light source emitting light transmitted through the portion analogous to portion310is energized, and in the next frame the light source emitting light transmitted through the portion analogous to portion314is energized. The processor receives only one image per frame and is able to transmit respective data for each image in each frame to the processor. The processor in turn is able to generate separate images for each of the analogous portions of the pump. The use of a monochrome image sensor and three backlights emitting the same spectrum reduces the cost of the pump in the example embodiment.

The following discussion provides further detail regardingFIGS. 16 through 19. It should be understood that the following discussion is applicable to the two-channel embodiments discussed above. In an example embodiment, lens elements (not shown) can be added to respective image paths (paths traversed by light from a light source to an image sensor) for systems300through600to compensate for unequal image paths. In an example embodiment, a spectrum of light in the near infra red range (for example, between 700 nm and 1,000 nm) can be used to illuminate portions306,310, or314. In an example embodiment, light source318and/or light sources318A/B/C are LEDs and the LEDs are pulsed to improve operating efficiency or create a strobe effect which eliminates motion blur of moving artifacts. The pulsing is synchronized with the shutter speed of image sensor322. In an example embodiment, the general configuration ofFIG. 18, which does not use a beam combiner, is modified by using three light sources as shown inFIG. 19. The resulting combination uses fewer mirrors than shown inFIG. 18, reducing the cost of the embodiment.

Thus, it is seen that the objects of the invention are efficiently obtained, although changes and modifications to the invention should be readily apparent to those having ordinary skill in the art, without departing from the spirit or scope of the invention as claimed. Although the invention is described by reference to a specific preferred embodiment, it is clear that variations can be made without departing from the scope or spirit of the invention as claimed.