Abstract:
A microscope fluid applicator includes an immersion fluid reservoir for storing immersion fluid and an applicator tip coupled to the immersion fluid reservoir. The microscope fluid applicator is releasably engaged to a moveable turret on a microscope. The microscope fluid applicator may be secured to an objective lens port on a turret of a microscope via threads. Immersion fluid is ejected from the applicator tip onto a sample holder. The turret may be rotated to place an immersion fluid objective into the immersion fluid. The sample may then be viewed through the immersion fluid. Any excess immersion fluid that is dispensed from the applicator tip may be collected in a fluid collector to prevent contamination of the microscope optics and other components.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority to U.S. Provisional Patent Application No. 60/692,862 filed on Jun. 22, 2005. U.S. Provisional Patent Application No. 60/692,862 is incorporated by reference as if set forth fully herein. 
    
    
     FIELD OF THE INVENTION 
     The field of the invention generally relates to microscopic devices and methods. More specifically, the invention relates to an immersion fluid applicator for fluid immersion microscopy. 
     BACKGROUND OF THE INVENTION 
     Microscopes often employ an immersion fluid during optical imaging. The immersion fluid (e.g., oil or the like) increases the index of refraction (as compared to air), thereby increasing the resolution of the resulting image. Conventional microscopes include complicated and cumbersome stage holders that allow for removal of a sample, delivery of immersion fluid, and replacement of the sample. Current microscopic devices that allow for replacement of immersion fluid are expensive and often minimally effective. The problem of immersion fluid loss due to shear (from rotating microscope objectives) and surface tension is particularly acute during large area scans. 
     For example, in many applications, samples are contained in well plates (e.g., 96 well plates) that are scanned by one or more objectives located on an inverted microscope. Immersion fluid is manually placed or interposed between the objective lens and the sample container (e.g., well plate). When the immersion fluid is lost during the scanning operation, an operator manually replaces the immersion fluid. Typically, this is done by placing a dropper or bottle tip in the small gap located between the objective lens and the specimen holder. Unfortunately, it is difficult for the operator to place the immersion fluid within this small space or gap. In addition, this process is inherently risky because during the replacement process it is possible to overfill the space with too much fluid, thereby causing spillage of the immersion fluid onto non-immersion fluid optics. In addition, fluid droppers and immersion fluid bottles are difficult to manage and often get coated by the immersion fluid which eventually finds its way onto a user&#39;s hands and/or gloves and ultimately onto the microscope optics. Moreover, conventional replacement of immersion fluid is problematic because the sample or specimen may not be moved to its original position or location after re-loading of the immersion fluid. Finally, because this process is a manual operation, the replacement of immersion fluid can significantly slow the speed at which samples may be scanned and may be a potential bottleneck for the overall imaging process. 
     There thus is a need for an immersion fluid applicator and method that is capable of easily and reliably placing immersion fluid between a microscopic objective lens and a sample holder. The system and method may be implemented without using the cumbersome droppers and bottles that have heretofore been used. In one preferred aspect of the invention, the immersion fluid applicator may be automatically controlled to place immersion fluid between a microscopic objective lens and a sample holder. There is a further need for an immersion fluid applicator that is able to reduce the overall amount of time required to replace lost or used immersion fluid. 
     SUMMARY OF THE INVENTION 
     In a first aspect of the invention, a microscope fluid applicator includes an immersion fluid reservoir for storing immersion fluid, an applicator tip coupled to the immersion fluid reservoir, and means for securing the immersion fluid reservoir to a moveable turret (automatically moveable or manually moveable) on a microscope. The means for securing the immersion fluid may include, for example, threads or the like. 
     In another aspect of the invention, a microscope includes a turret having a plurality of objective lens ports therein. A microscope fluid applicator is located in one of the objective lens ports. The microscope fluid applicator includes an immersion fluid reservoir for storing immersion fluid, an applicator tip coupled to the immersion fluid reservoir, and means such as threads for securing the immersion fluid reservoir to a moveable turret on a microscope. 
     In another aspect of the invention, a microscope fluid applicator for use with a microscope includes an immersion fluid reservoir for storing immersion fluid. An applicator tip is coupled to the immersion fluid reservoir. The microscope fluid applicator is releasably engageable with a moveable turret on the microscope. For example, the microscope fluid applicator may be screwed into a port on the turret that is typically used for microscope objectives. The microscope fluid applicator may contain threads so the same can be readily loaded and un-loaded onto the turret. 
     In still another aspect of the invention, a microscope includes a moveable turret having a plurality of objective lens ports therein. A microscope fluid applicator is adapted for mounting in one or more of the objective lens ports. The microscope fluid applicator includes an immersion fluid reservoir for storing immersion fluid, an applicator tip coupled to the immersion fluid reservoir, and a threaded portion for securing the immersion fluid reservoir to the moveable turret on the microscope. 
     In yet another aspect of the invention, a method of applying immersion fluid to a sample holder for viewing with a microscope includes loading a microscope fluid applicator into a moveable turret of the microscope, the microscope fluid applicator containing immersion fluid therein. The moveable turret is rotated so as to position the microscope fluid applicator adjacent to the sample holder. Immersion fluid is then dispensed from the microscope fluid applicator onto the sample holder. The turret may then be moved (e.g., rotated) to position an immersion fluid objective over the sample holder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a microscope fluid applicator according to one aspect of the invention. 
         FIG. 2A  illustrates a microscope turret having an air objective, an immersion fluid objective, and a microscope fluid applicator. The air objective is shown adjacent to a sample holder. 
         FIG. 2B  illustrates a microscope turret having an air objective, an immersion fluid objective, and a microscope fluid applicator. The microscope fluid applicator is shown adjacent to a sample holder. 
         FIG. 2C  illustrates a microscope turret having an air objective, an immersion fluid objective, and a microscope fluid applicator. The immersion fluid objective is shown adjacent to a sample holder. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  illustrates a microscope fluid applicator  2  according to one aspect of the invention. The microscope fluid applicator  2  includes an immersion fluid reservoir  4  for storing immersion fluid  6  such as oil, water, or glycerin. An applicator tip  8  is coupled to the immersion fluid reservoir  4 . The applicator tip  8  may be tapered in the shape of a “beak” or the like that terminates in a distal tip  10 . For example, the “beak” may comprise a long, thin tube that is designed to minimize air bubbles in the system. In addition, the “beak” may be formed to control the flow rate and to control the fluid drop size that emerges from the applicator tip  8 . Of course, the applicator tip  8  need not necessarily have a beak-like shape. Other geometrical shapes and cross-sectional profiles are contemplated to fall within the scope of the invention. The distal tip  10  may be a pressure-sensitive tip such as those that operate in ball point or gel-type pens. In this regard, a ball valve  12  or the like may be located in the distal tip  10  to modulate the flow of immersion fluid  6  from the applicator tip  8 . For example, contact of the ball valve  12  (or the like) with a sample holder  20  (as shown in  FIGS. 2A-C ) will cause immersion fluid  6  to flow (either due to one or more of: gravitational forces, pressure, capillary forces, or other wicking force) onto the sample holder  20 . Other delivery modalities can also be realized. For example, the delivery of fluid  6  may be initiated by contact of the distal tip  10  with, for example, a cover slip on the sample holder  20 . 
     In one optional aspect of the invention, the applicator  2  may be moveable relative to the sample holder  20 . For example, the applicator  2  and/or sample holder  20  may be moveable in a vertical (or substantially vertical) direction such that size of the gap between the applicator tip  8  and the sample holder  20  may be adjusted. Either one or both of the sample holder  20  or applicator  2  (or turret  16  as described below) may be coupled to an adjuster that controls the size of the gap. For example, the adjuster may be a manually adjuster such as a knob, slide, or the like. Alternatively, the adjuster may be an automatically controlled motor or driver. 
     The applicator  2  may include a location sensing mechanism that identifies the proximity of, for example, the microscope stage or cover slip. For example, a precision encoder, laser-based sensor, or the like may detect the presence or position of the distal tip  10  with respect to the sample holder  20 . When the distance between the distal tip  10  of the applicator  2  and the sample holder  20  (or cover slip or stage) reaches a certain threshold distance, a pump or similar dispensing device may be actuated to dispense immersion fluid  6 . 
     In an alternative configuration, the immersion fluid  6  is pressurized, for example, by a pressurized gas or liquid which is located behind or proximal to the immersion fluid  6 . When the distal tip  10  (or valve contained therein) comes into contact with the surface of sample holder  20  (shown in  FIG. 2B ), immersion fluid  6  is delivered to the surface of the sample holder  20  to replenish immersion fluid  6  to the gap or space formed between the sample holder  20  and any objective lens (described below). 
     It should be understood that the sample holder  20  may include a slide, cover slip, or array of wells (e.g., a 96 well plate or the like). Alternatively, the immersion fluid  6  is pressurized only when the distal tip  10  of the applicator  2  engages with a sample holder  20 . In this regard, the pressure is self-generated by the applicator  2  upon engagement with the holder  20 . For example, plunger (not shown) or the like situated within the immersion fluid reservoir  4  may be coupled to an actuator that is depressed or otherwise triggered when the distal tip  10  of the applicator  2  is adjacent to the sample holder  20 . For example, the actuator may physically touch the sample holder  20 . Further movement of the actuator may trigger the release of immersion fluid  6  from the immersion fluid reservoir  4 . 
     The microscope fluid applicator  2  further includes an interface for securing the microscope fluid applicator  2  to a moveable turret  16  on a microscope (shown in  FIGS. 2A-2C ). In one aspect of the invention, the immersion reservoir  4  contains threads  18  such that the microscope fluid applicator  2  may be screwed into the objective lens port(s) of the microscope turret  16 . Of course, other means to secure the microscope fluid applicator  2  may also be used such as clips or other retaining members. 
     Still referring to  FIG. 1 , the microscope fluid applicator  2  may optionally include a fluid collector  30  for collecting excess immersion fluid  6  that may be ejected from the applicator  2 . The fluid collector  30  may take the form of a lumen, dam, well or the like (a dam is shown in  FIG. 1 ) that prevents immersion fluid  6  from contacting other areas of the microscope. For example, excess immersion fluid  6  may run down the side of the applicator tip  8  to be collected in the fluid collector  30 . In another aspect, a port or lumen  32  may drain back into an internal reservoir. In another example, the microscope fluid applicator  2  may contain multiple fluid reservoirs. For example, one reservoir may contain immersion fluid  6  while another reservoir contains a rinsing fluid which can flow out of the applicator  2  and pick-up excess oil from the sample holder  20  and flow back into the fluid collector  30 . 
     In one aspect of the invention, the microscope fluid applicator  2  may contain two lumens or chambers, one of which houses the immersion fluid reservoir  4  or cartridge and a second which collects any excess immersion fluid  6  which may flow from the applicator tip  8 . 
     The microscope fluid applicator  2  may be used on either an upright or inverted microscope. One or more portions of the microscope fluid applicator  2  may be disposable. For example, the applicator  2  may include a housing or the like which includes threads  18  for engaging a microscope turret  16 . A disposable bottle or cartridge (e.g., fluid reservoir  4 ) may be screwed or otherwise inserted into the housing. The disposable bottle or cartridge may incorporate an applicator tip  8  which may or may not be disposable. Alternatively, the entire microscope fluid applicator  2  may be disposable. 
     During operation of the microscope fluid applicator  2 , a user may load the applicator  2  into an existing objective lens port  15  on a turret  16  of a microscope.  FIGS. 2A-2C  illustrate one such microscope fluid applicator  2  loaded on a turret  16  containing an immersion fluid objective  22  and an air objective  24 . In this configuration, the air objective  24  may be used to first scan a sample or specimen loaded onto a sample holder  20  at a low resolution. Prior to switching to the higher resolution fluid objective  22 , the air objective  24  is rotated away from the sample holder  20  to bring the microscope fluid applicator  2  adjacent to the sample holder  20  (as shown in  FIG. 2B ). Immersion fluid  6  is then dispensed from the applicator  2  onto the sample holder  20  using one of the techniques described above. After immersion fluid  6  has been dispensed, the turret  16  is rotated once again to place the fluid objective  22  adjacent to the sample holder  20  such that immersion fluid  6  is interposed between the fluid objective  22  and the sample holder  20  (shown in  FIG. 2C ). The sample or specimen can now be viewed at higher resolution. It should be understood, however, that the invention described herein is not limited to applications having a first low-resolution air scan followed by a later higher-resolution immersion scan. 
     The microscope fluid applicator  2  takes advantage of the low tolerance engineering common to laboratory grade microscopes. In these microscopes, particularly automated designs, each objective in the turret  16  can be rotated into place with high precision and repeatability of alignment so that the specimen stays centered each time the objective (e.g., turret  16 ) is rotated out of place and returned to its original position. 
     As best seen in  FIGS. 2A-2C , the microscope fluid applicator  2  takes the immersion fluid bottle (or dropper) out of the hands of the user. With the microscope fluid applicator  2 , the user only needs to rotate the turret  16  containing the microscope fluid applicator  2  into position. In one aspect of the invention, the microscope fluid applicator  2  is then raised/lowered to dispense the immersion fluid  6  onto the sample holder  20 . This may be done either manually or by automatic actuation using, for example, the microscope&#39;s existing focus system. The turret  16  is then lowered (or raised as the case may be) and rotated to place the immersion fluid objective  22  into position (see  FIG. 2C ). For automated microscopes, the focus position of the turret  16  at which the microscope fluid applicator  2  will deliver a drop (or more) of immersion fluid  6  can be programmed into the hardware, firmware, or software of the associated controller (e.g., a computer control system). In addition, in one aspect of the invention, the delivery of immersion fluid  6  can be automated with a push of a button or switch. For example, in a computer-controlled system, a click of the mouse (or other input device) may trigger delivery of the immersion fluid  6 . Alternatively, a macro or algorithm may be employed in which the fluid delivery is done independent of any additional user input. For example, a computer control system may detect the proximity of the sample holder  20  relative to the distal tip  8  of the microscope fluid applicator  2  and automatically dispense the appropriate amount of immersion fluid  6 . 
     Still referring to  FIGS. 2A-2C , in one aspect of the invention, an air objective  24  is used for low-resolution scanning of the specimen. When it is desirable to switch to an immersion fluid objective  22  such as an oil immersion objective  22 , the microscope fluid applicator  2  is rotated below the specimen (or sample holder  20 ) and an aliquot of immersion fluid  6  is applied to the sample holder  20 . Finally, the immersion fluid objective  22  is rotated under the sample holder  20  and raised to make contact with the immersion fluid  6 . 
     The present invention may be incorporated into microscopes including, for example, research microscopes. This includes microscopes utilized for micro-fabrication, biomedical research, biotech research, cellular biology research, and bioengineering research. 
     While embodiments of the present invention have been shown and described, various modifications may be made without departing from the scope of the present invention. The invention, therefore, should not be limited, except to the following claims, and their equivalents.