Sampling device

A sampling device is disclosed. The device comprises a capillary tube having a first orifice for collecting and dispensing a liquid at one end of the tube and a second orifice at the other end of the tube. A chamber encloses the second orifice. The device has a small opening to the outside atmosphere, other than the first orifice, communicating with the capillary tube. Also included is substantially non-compressible means movable with respect to said opening for concomitantly sealing said opening and forcing air from said chamber through said capillary tube.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to devices for collecting and dispensing of liquids, 
particularly those liquids which are in a puddled form or in an open 
container. The device is particularly suited for the collection of blood 
from a blood drop. 
Pipetting devices are known which employ capillary action to take a sample 
into the device. Such devices generally have a compressible (squeeze) 
bulb, usually with an opening in its wall. With the opening unobstructed, 
the sample fills a capillary tube. A finger is placed over the opening and 
the bulb is compressed to force the sample out of the tube. Manipulation 
of the squeeze bulb is, however, cumbersome. Such pipetting devices are 
not particularly useful in doctor's offices and diagnostic laboratories 
for taking small samples of, for example, blood from a puddle obtained by 
pricking a patient's finger. 
Syringes for taking samples are also known. The syringe requires mechanical 
movements to fill the syringe with a sample and also to dispense the 
sample. Accurate sampling with a syringe usually requires a relatively 
expensive device. Ideally, the sampling portion of a sampling device 
should not be reusable. Consequently, the one-time use of a relatively 
expensive syringe is undesirable, but often unavoidable. In addition, the 
appearance of a syringe with a long needle often results in patient 
stress. 
There is a need, therefore, for a sampling device which allows sampling 
without mechanical movement and dispensing of a precise amount of sample 
by means of mechanical movement. 
2. Description of the Prior Art 
A rinsing pipette is disclosed in U.S. Pat. No. 3,233,785. An apparatus for 
measuring precise microquantities of fluid samples is described in U.S. 
Pat. No. 4,003,262. A telescoping serum separator and dispenser is 
disclosed in U.S. Pat. No. 4,052,320. In U.S. Pat. No. 4,136,036 there is 
disclosed a collection and dispensing device for non-pressurized liquids. 
A device for the extraction of capillary blood is disclosed in U.S. Pat. 
No. 4,396,024. 
SUMMARY OF THE INVENTION 
The present invention is a sampling device for collecting and dispensing of 
liquids. The sampling device comprises a capillary tube which has a first 
orifice for collecting and dispensing a liquid at one of its ends and a 
second orifice at its other end. A chamber encloses the second orifice. 
The device has an opening to the outside atmosphere, other than the first 
orifice, communicating with the capillary tube. Also included is 
substantially non-compressible means movable with respect to the opening 
for concomitantly sealing the opening and forcing air from the chamber 
through the capillary tube. 
The sampling device of the present invention thus has the advantage of 
allowing sampling of a liquid without mechanical movement such as that 
found in a syringe. Additionally, the present device has the advantage of 
having a simple action, similar to the action of a syringe, for dispensing 
a precise amount of sample. The use of cumbersome, and often inaccurate, 
squeeze bulbs is avoided. Also avoided is a syringe-like appearance.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS 
The device of the present invention is useful for collecting and dispensing 
samples of liquid. In its broadest aspect the sampling device comprises a 
collection tube which has a capillary passage extending the entire length 
of the collection tube. The capillary passage has a collecting and 
dispensing orifice at one end of the tube and a second orifice at its 
other end. A chamber encloses the second orifice at the other end of the 
tube. The device has a small opening to the outside atmosphere other than 
that provided by the first orifice. The opening communicates with the 
capillary passage in the capillary tube and provides for pressure 
equalization between the interior and exterior of the chamber. Adjacent 
the chamber is substantially non-compressible, usually rigid, movable 
means. Generally, this means provides for concomitantly sealing the 
opening usually by moving at least one wall of the chamber relative to the 
opening. This movable means and the tube are in a first position which 
allows pressure equalization through the opening of the chamber and allows 
liquid to fill the capillary passage by means of capillary action. The 
movable means and the tube are manipulatable to a second position which 
prevents pressure equalization through the opening and defines a chamber 
volume which is greater than a predetermined volume of the capillary 
passage. Further movement of the means forces the defined volume of air 
from the chamber through the capillary passage and results in a dispensing 
of liquid in the capillary passage. 
The sampling device of the present invention is particularly suited for 
collecting and dispensing serum and whole blood samples. However, any 
liquid which is capable of wetting the capillary surface so as to permit 
capillary migration in the capillary passage of the collection tube may be 
collected and dispensed using a sampling device in accordance with the 
present invention. Such other liquids include, but are not limited to, 
water, aqueous solutions, solvents such as alcohols, ethers, hydrocarbons, 
dimethylsulfoxide, formamides, esters, acids, amines, and the like. 
In one aspect of the present invention, the sampling device comprises a 
housing having a chamber with a collection tube telescopically mounted 
therein. The collection tube has a capillary passage which extends from 
one end of the tube to the other. The capillary passage has a collecting 
and dispensing orifice at one end of the tube. The housing has a small 
opening extending to the outside atmosphere providing for pressure 
equalization which results from gas communication between the chamber and 
the extreme atmosphere. Sealing means are provided between the collection 
tube and the housing to prevent such pressure equilibration when the 
collection tube is moved past the opening. Liquid is drawn into the 
capillary by capillary action when the tube is in an extended position 
allowing such pressure equalization; liquid is ejected when the tube is 
moved into the chamber and pressure equalization is prevented, provided a 
chamber volume is defined which is greater than the volume of liquid to be 
ejected. 
The term "capillary action" is used herein to refer to the force or 
phenomena obtained when the free surface of liquid being collected wets 
the confining walls of the capillary passage and the liquid surface, 
because of surface tension, moves along the confining walls of the 
capillary passage. More liquid is drawn into the capillary passage until a 
head of liquid is achieved in which gravity prevents further increase in 
liquid volume, until the source of liquid is removed, or until the entire 
capillary is filled. 
The collection tube is telescopically mounted in the chamber in the housing 
in a first or extended position wherein pressure equalization with the 
atmosphere exists in the chamber as a result of the opening. The housing 
and the tube are movable to a second position wherein such pressure 
equalization is prevented by blocking of the opening and, if necessary, 
the use of sealing means between the tube and the housing. Simultaneously, 
a chamber volume is defined which is sufficient to permit the further 
movement of the tube to a retracted position and to provide a displacement 
of air sufficient to pressurize the chamber and forcibly eject the liquid 
from the capillary passage. 
The sampling devices in accordance with the present invention can be 
further illustrated by reference to the attached drawings. 
FIG. 1 is illustrative of one embodiment of a sampling device in accordance 
with the present invention. Collection tube 10 is provided with capillary 
passage 11, which has collecting and dispensing orifice 12 at one end of 
tube 10. Capillary passage 11 is formed by walls 13 of collection tube 10 
and generally has a uniform cross-section. Collection tube 10 is 
preferably narrowed at the inlet orifice to provide for a more precise 
contact of orifice 12 with the liquid sample to be collected and to 
minimize wetting of the external surface of 10 and inaccuracy due to 
carryover. The other end (14) of the collection tube is mounted in a bore 
in housing 15 which forms chamber 16. The size of chamber 16 is designed 
to accommodate the end portion 14 of collection tube 10. Opening 17 
extends from the exterior to the interior of housing 15, and has a 
diameter which will be sufficient to provide gas communication and 
pressure equalization between the exterior of 15 and chamber 16. Housing 
15 with chamber 16 is formed by walls 18. 
The inner dimensions of chamber 16 and the outer dimensions of collection 
tube 10, particularly above opening 17, will be such as to substantially 
limit the amount of gas which will escape around the tube. Thus, tube 10 
must fit chamber 16 accordingly or sealing means 19 must be provided above 
17 to prevent significant pressure loss when 10 is moved past opening 17 
further into chamber 16. Exemplary of such sealing means are O-rings 
having suitable flexibility to allow collection tube 10 to be moved within 
chamber 16. Rubber O-rings may be used. However, other means for providing 
the gas tight seal between end 14 of collection tube 10 and chamber 16 
above opening 17 will be suggested to those skilled in the art. For 
example, one may use a circumferential ridge on the inner wall of the 
chamber or one may use a suitable grease to achieve the sealing function. 
Additionally, guide means 20 may be provided in chamber 16 below opening 17 
in order to frictionally maintain tube 10 in chamber 16 in the event that 
a frictional fit is not realized without such guide means. The guide means 
may take the form of two or more longitudinal ribs in chamber 16 in a 
generally parallel relationship with the tube. The dimensions and 
composition of the sealing means will be such as to frictionally maintain 
tube 10 in chamber 16 and allow movement of tube 10 in chamber 16. 
The inner dimensions of chamber 16 and the position of opening 17 therein, 
may be generally characterized according to the function which one desires 
to achieve in using the sampling device. When capillary passage 11 is 
filled with a liquid, it is desired to dispense such fluid through orifice 
12. This may be achieved by manipulating the device generally by causing 
the housing to move in the direction of orifice 12, from the position 
shown in FIG. 1 to a position wherein pressure equalization is no longer 
achieved through opening 17 between the interior and exterior of housing 
15. Thus, the inner dimensions of chamber 16 and the location of opening 
17 should be such as to (a) allow accommodation of collection tube 10 and 
(b) permit collection tube 10 to be moved within housing 15 to a position 
which blocks fluid communication through opening 17 and (c) further permit 
the liquid in capillary passage 11 to be dispensed through orifice 12. 
Liquid is forced from capillary passage 11 when the collection tube passes 
opening 17 thus blocking pressure equalization. Air trapped in chamber 16 
pushes the liquid in capillary passage 11 out of the collection tube 
through orifice 12. Thus, one characteristic of the sampling device of the 
present invention is that collecting and dispensing a liquid is achieved 
through the same orifice. 
The sampling device of the present invention provides collecting and 
dispensing of precise predetermined amounts of a liquid. Collection of the 
liquid is obtained without precision pumping and positive displacement is 
provided to give a quantitative measure. 
Capillary passage 11 will have dimensions which correspond exactly to the 
predetermined amount of liquid one desires to have dispensed. The 
particular volume of the capillary passage for any given device will 
depend upon the intended use of the device and the liquid to be sampled. 
The length of the passage should be less than the minimum height of the 
capillary action for the liquid to be sampled. Normally, a capacity of 0.1 
to 100 microliters is considered to be a practical range. Often, the 
capacity of the passage will be less than 100 microliters, frequently less 
than 50 microliters, more usually less than 25 microliters. Volumes of 
liquids about 1.0 to 15.0 microliters can be conveniently measured. 
The inner dimensions of chamber 16 and the placement of opening 17 within 
16 will be such as to provide, after pressure equalibration is prevented 
through opening 17, a volume of air which is greater than the volume of 
liquid to be dispensed and thus is greater than the total volume of the 
capillary passage. Such a situation may be achieved, e.g., by sealing 
opening 17 at an early stage of movement of housing 15 in the direction of 
orifice 12. For the embodiment depicted in FIGS. 1 and 2, opening 17 may 
be close to the end of tube 10 enclosed by the chamber. Further movement 
of collection tube 10 toward orifice 12 allows one to dispense the entire 
precisely measured, predetermined amount of liquid from the capillary 
passage. 
The walls of the capillary tube must have a thickness sufficient to achieve 
the forcing of the defined volume of air through the capillary passage and 
thus dispense the liquid contained therein. The capillary tube may be 
thin-walled with an outside diameter equal to about twice the inside 
diameter or it may be thick-walled with an outside diameter much greater 
than the inside diameter. The diameter of the capillary passage generally 
will be less than 2 mm, preferably less than 1 mm and normally greater 
than 0.1 mm. 
For example, if one desires to obtain a sample of exactly 5 microliters of 
a liquid, the volume of capillary passage 11 will be exactly 5 
microliters. The volume of inner chamber 16 located beyond opening 17 
should have dimensions which define a volume in excess of 5 microliters so 
that air trapped in the chambers will be forced out through capillary 
passage 11. Any residual liquid that might otherwise remain on the walls 
of capillary passage 11 after dispensation is also ejected. 
Sampling devices of the present invention can be manufactured from any 
suitable material. Illustrative of the considerations for the selection of 
a suitable material are (a) non-reactivity with and insolubility in the 
liquid sample to be collected, (b) sufficient rigidity to allow for the 
manipulation of the device in accordance with the invention, (c) 
wettability, (d) transparency, and (e) low temperature coefficient of 
expansion relative to the required accuracy of the device. Housing 14 and 
collection tube 10 may be made of the same material or they may be made of 
different material. The collection tube is preferably made of glass but 
may be made of any material that is substantially rigid or 
non-compressible, wettable, non-reactive, and insoluble with a low 
temperature coefficient of expansion. Preferably, the entire device will 
be made of transparent material to allow visual confirmation that the 
sample is fully drawn into and fully dispensed. The collection tube may be 
constructed of non-wettable material provided the capillary surface is 
coated with a wettable surfactant. The surfactant, of course, should not 
be reactive with the liquid being collected. The housing normally will not 
contact the liquid. The housing may be made of a substantially 
non-compressible material which allows a suitable interaction with the 
collection tube according to the function desired of the present device. 
The collection tube 10 should be movable within housing 15. Materials from 
which the sampling device of the present invention may be made include 
glass, synthetic rigid polymers or plastics, e.g., vinyl 
chloride-vinylidene chloride copolymer, polyesters, polystyrene, acrylics, 
and the like. 
Another embodiment of the sampling device of the present invention is 
depicted in FIGS. 4-6. The numbering convention used in FIGS. 4-6 has been 
designed so that the second digit of the number is the same as the second 
digit of the number of the corresponding element found in the sampling 
device depicted in FIGS. 1-3. Capillary tube 30 with capillary passage 31 
has orifice 32 at one end. The capillary passage is defined in tube 30 by 
wall 33. The other end (34) of capillary tube 30 is mounted in housing 35, 
which has chamber 36 defined by wall 39. Opening 37 in this particular 
embodiment is in the form of a longitudinal notch in wall 38 extending 
from the base of the wall to a point above top portion 34 of tube 32. 
Opening 37 provides pressure equalization between the exterior of the 
device and chamber 36. The device further includes sealing means 39. 
Capillary tube 30 is mounted in housing 35 in a first or extended position 
such that pressure equalization exists between the exterior of the device 
and the interior of chamber 36. In this way a liquid sample can be drawn 
into capillary passage 31 by the force of capillary action when the device 
is in a first, in this case, extended position. Collection tube 30 is 
movable within chamber 36 to a second position where pressure equalization 
is prevented through opening 37. Movement of collection tube 30 within 
chamber 36 beyond the second position and past sealing means 39 to a 
retracted position forces any liquid contained in capillary passage 31 out 
of the collection tube through inlet 32. 
As mentioned earlier, the sampling device of the present invention is 
particularly suited for collecting puddled liquids such as blood from a 
blood drop produced by a pin prick. There are a number of situations in 
which collection of such sample is desirable. For example, in diagnostic 
methods collection of precise amounts of a sample of liquid may be 
required. The present device is particularly suited for use in conjunction 
with the collection of samples for performing an assay. 
The sampling device of the present invention is suitable for use in 
conjunction with a diagnostic immunochemical test device. The present 
sampling device can be used separately from such test device to collect a 
sample. However, the present sampling device may also be an integral part 
of the test device. 
An example of such a device is depicted in FIG. 7. The numbering convention 
used in FIG. 7 has been designed so that the second digit of the number is 
the same as the second digit of the number of the corresponding element 
found in the sampling device depicted in FIG. 1. Capillary tube 60 with 
capillary passage 61 has orifice 62 at one end. The capillary passage is 
defined in tube 60 by wall 63. The other end (64) of capillary tube 60 is 
mounted in housing 65, which housing serves a dual function. Housing 65 
also accommodates a diagnostic test device such as an immunochemical strip 
which is found on the front of the test device and is not shown. Housing 
65 has chamber 66 which is defined by wall 68 of housing 65. Small opening 
67 provides pressure equalization between the exterior of the device and 
chamber 66. Capillary tube 60 is mounted in housing 65 in a first position 
such that pressure equalization exists between the exterior of the device 
and the interior of chamber 66. In this way a liquid sample, in this case 
a blood sample, is drawn into capillary passage 61 by the force of 
capillary action. Collection tube 60 is movable within chamber 66 to a 
second position where pressure equalization is prevented through opening 
67. Movement of collection tube 60 within chamber 66 beyond the second 
position and through sealing means 69 forces any liquid contained in 
capillary passage 61 out of the collection tube through inlet 62. 
The device depicted in FIG. 7 provides a number of advantages over a system 
where the sampling device and the test device are provided separately. The 
first advantage is that there is one less device to be dealt with in 
carrying out a diagnostic test. In addition, there would be a cost 
reduction in the manufacture of such a dual test device since one need not 
manufacture two separate devices, one for collecting and dispensing a 
sample and one for conducting the diagnostic test. 
Another embodiment of the sampling device of the present invention is 
depicted in FIG. 8 and FIG. 9. Referring now to FIG. 8 and FIG. 9, 
collection tube 70 has capillary passage 71 with orifice 72 at one end of 
collection tube 70. Capillary passage 71 is formed in 70 by wall 73. The 
other end of collection tube 70 is a chamber 74 which may be a separate 
part (not shown) or an integral part (shown) of collection tube 70. 
Chamber 74 is defined by wall 75 which has a small opening 76 extending 
from the exterior of 74 to its interior. Chamber 74 has a base 77 in which 
capillary passage 71 terminates at 78. Chamber 74 has an opening 79 at its 
top to accomodate plug 80, which is movably mounted in chamber 74. The 
dimensions of chamber 74, passage 71 and plug 80 are such as to achieve 
the collecting and dispensing of a liquid. Plug 80 is in a first position 
wherein pressure equalization is allowed through opening 76 from the 
interior of chamber 74 to the exterior of chamber 74 and liquid may enter 
capillary passage 71. Plug 80 is movable to a second position through 
sealing means 81 wherein pressure equalization through opening 76 is 
prevented. As a result any liquid in capillary passage 71 is forced out of 
the passage through orifice 72. 
It is within the scope of the present invention to include a prepackaged 
breakable capsule within the chamber of the present sampling device. The 
prepackaged breakable capsule could contain, for example, a predetermined 
amount of a diluent such as an aqueous buffer which would wash out the 
liquid in the capillary passage and dilute the liquid quantitatively. The 
capsule could be fabricated from a suitable breakable material which would 
be compatible with the ultimate use of the sampling device including the 
liquid to be sampled. Exemplary of suitable materials for the capsule are 
glass, breakable plastic, and the like. FIG. 10 depicts the device of FIG. 
1 which further contains capsule 90 in chamber 16. 
There are also additional advantages which are generally realized by 
employing the sampling device of the present invention. The present 
sampling device does not resemble a syringe in that it lacks a needle-like 
member. Syringes and needles tend to have a disturbing effect on a 
patient's peace of mind. Secondly, the present sampling device provides a 
minimum number of manipulative steps to achieve sample collecting and 
dispensing. The method for collecting and dispensing a sample in 
accordance with the present invention involves contacting a sample with 
the collecting and dispensing orifice of the present sampling device. No 
mechanical action is required. The sample is allowed to traverse the 
capillary passage by capillary action. The device is then manipulated from 
a first position to a second position which prevents pressure equilization 
between the interior and exterior of the chamber. Further manipulation of 
the device results in removal of the sample from the capillary passage. 
Basically, then, only two manipulative steps are involved. 
Another advantage of the sampling device of the present invention is that 
no external collection force, such as suction and the like, is required to 
collect the sample. This advantage is particularly important for a 
non-syringe-like device for use in collecting very small amounts of a 
liquid from a small sample. A further advantage of the present device is 
that it is small and capable of being designed for both precise and 
imprecise volume collection of a sample. Where a precise or accurate 
amount of a sample must be dispensed into a system, the present device may 
be designed to provide such a quantitative amount. 
The use of the sampling device of the present invention is illustrated in 
FIGS. 11-13. Referring to FIG. 11, the sampling device as depicted in FIG. 
1 is contacted with a blood drop on the finger of a patient obtained by 
pricking the patient's finger. In FIG. 11 the blood is shown traversing 
the capillary passage by capillary action. When capillary action no longer 
draws blood into the capillary passage, and, thus, a predetermined volume 
is obtained, the sampling device is removed from the source of the sample 
and placed in a container as shown in FIG. 12. In this case, the container 
is filled with a liquid medium with which the dispensed blood will mix. 
FIG. 13 depicts the blood sample now mixing with the contents of the tube. 
The blood sample was forced from the sampling device of the invention by 
movement of housing 15 in the direction of orifice 12. This may be 
accomplished, e.g., by placing the collecting and dispensing end of the 
collection tube against the bottom of the container and pushing downward 
on the top of portion of the device. 
The invention has been described in detail with particular reference to the 
above embodiments. It will be understood, however, that variations and 
modifications can be effected within the spirit and scope of the invention 
.