U.S. patent application number 17/205001 was filed with the patent office on 2022-09-22 for pipette-fillable cartridge fluid detection.
This patent application is currently assigned to Funai Electric Co., Ltd.. The applicant listed for this patent is Funai Electric Co., Ltd.. Invention is credited to Bruce A Deboard, Bruce D. Gibson, Michael A. Marra, III.
Application Number | 20220297424 17/205001 |
Document ID | / |
Family ID | 1000005491705 |
Filed Date | 2022-09-22 |
United States Patent
Application |
20220297424 |
Kind Code |
A1 |
Deboard; Bruce A ; et
al. |
September 22, 2022 |
PIPETTE-FILLABLE CARTRIDGE FLUID DETECTION
Abstract
A digital dispense system and method of using a digital dispense
system. The digital dispense system includes a pipette-fillable
fluid cartridge having one or more fluid chambers therein and
having an ejection head attached thereto. The ejection head
contains a plurality of fluid ejectors thereon. The fluid ejectors
are in fluid flow communication with the one or more fluid chambers
of the pipette-fillable fluid cartridge. A fluid detection circuit
is disposed on the ejection head and associated with at least one
of the plurality of fluid ejectors for signaling the presence or
absence of fluid in the one or more fluid chambers.
Inventors: |
Deboard; Bruce A;
(Lexington, KY) ; Gibson; Bruce D.; (Lexington,
KY) ; Marra, III; Michael A.; (Lexington,
KY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Funai Electric Co., Ltd. |
Osaka |
|
JP |
|
|
Assignee: |
Funai Electric Co., Ltd.
Osaka
JP
|
Family ID: |
1000005491705 |
Appl. No.: |
17/205001 |
Filed: |
March 18, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B41J 2/14 20130101; B41J
2/04541 20130101 |
International
Class: |
B41J 2/045 20060101
B41J002/045; B41J 2/14 20060101 B41J002/14 |
Claims
1. A digital dispense system comprising: a pipette-fillable fluid
cartridge having one or more fluid chambers therein and having an
ejection head attached thereto, the ejection head containing a
plurality of fluid ejectors thereon, wherein the fluid ejectors are
in fluid flow communication with the one or more fluid chambers of
the pipette-fillable fluid cartridge; and a fluid detection circuit
disposed on the ejection head and associated with at least one of
the plurality of fluid ejectors for signaling the presence or
absence of fluid in the one or more fluid chambers.
2. The digital dispense system of claim 1, wherein the fluid
detection circuit is selected from the group consisting of (a) a
conductivity sense circuit, (b) a thermal sense circuit, and a
combination of (a) and (b).
3. The digital dispense system of claim 2, wherein the conductivity
sense circuit comprises a first electrode in electrical
communication with at least one of the plurality of fluid ejectors,
and a second electrode disposed in a fluid flow path to at least
one of the plurality of fluid ejectors.
4. The digital dispense system of claim 2, wherein the thermal
sense circuit comprises a voltage slope detect circuit for at least
one of the plurality of fluid ejectors.
5. The digital dispense system of claim 1, wherein the fluid
cartridge comprises two or more discrete fluid chambers.
6. The digital dispense system of claim 1, wherein the ejection
head comprises two or more arrays of fluid ejectors thereon and at
least one fluid ejector from each of the two or more arrays of
fluid ejectors is associated with the fluid detection circuit.
7. A method for dispensing fluid with a digital dispense system,
comprising: providing a pipette-fillable fluid cartridge having one
or more fluid chambers therein and having an ejection head attached
thereto, the ejection head containing a plurality of fluid ejectors
thereon, wherein the fluid ejectors are in fluid flow communication
with the one or more fluid chambers of the pipette-fillable fluid
cartridge; and a fluid detection circuit is disposed on the
ejection head and associated with at least one of the plurality of
fluid ejectors for signaling the presence or absence of fluid in
the one or more fluid chambers; filling at least one of the one or
more fluid chambers with a fluid to be dispensed; activating a
diagnostic function of the digital dispense system to determine if
the fluid to be dispensed is present in or absent from the at least
one of the one or more fluid chambers; and initiating a fluid
dispense sequence in an absence of an error or warning from the
diagnostic function.
8. The method of claim 8, wherein the fluid detection circuit is
selected from the group consisting of (a) a conductivity sense
circuit, (b) a thermal sense circuit, and a combination of (a) and
(b).
9. The method of claim 8 wherein the conductivity sense circuit
comprises a first electrode in electrical communication with at
least one of the plurality of fluid ejectors, and a second
electrode disposed in a fluid flow path to at least one of the
plurality of fluid ejectors.
10. The method of claim 8, wherein the thermal sense circuit
comprises a voltage slope detect circuit for at least one of the
plurality of fluid ejectors.
11. The method of claim 7, further comprising modifying the fluid
dispense sequence in the presence of an error or warning from the
diagnostic function that indicates an incorrect fluid in the at
least one of the one or more fluid chambers.
12. The method of claim 7, further comprising modifying the fluid
dispense sequence in the presence of an error or warning from the
diagnostic function that indicates that fluid is absent from at
least one of the one or more fluid chambers.
13. The method of claim 7, further comprising terminating the fluid
dispense sequence in the presence of an error or warning from the
diagnostic function that indicates that fluid is absent from at
least one of the one or more fluid chambers.
14. A digital dispense system comprising: a pipette fillable
cartridge having at least one fluid chamber therein and an ejection
head in fluid flow communication with the at least one fluid
chamber, wherein the ejection head contains a plurality of fluid
ejectors and a fluid detection circuit thereon; a processor
disposed in the digital dispense system configured with a fluid
detect algorithm, wherein the processor is in electrical
communication with the fluid detection circuit for activating an
error signal in the absence of fluid; and a user input device for
modifying or terminating a fluid dispense sequence upon error
signal activation.
15. The digital dispense system of claim 14, wherein the fluid
detect algorithm is programmed to use (a) fluid conductivity data,
(b) ejector thermal data, or a combination of (a) and (b) to
determine if a fluid is present in the at least one fluid
chamber.
16. The digital dispense system of claim 15, wherein the fluid
detect algorithm is programmed to (i) use fluid conductivity data
initially and to (ii) use ejector thermal data if fluid is not
found by (i).
17. The digital dispense system of claim 14, wherein the
pipette-fillable cartridge comprises two or more fluid chambers and
wherein the fluid detect algorithm is programmed to determine if a
fluid is absent from a predetermined one of the two or more fluid
chambers.
18. The digital dispense system of claim 14, wherein the fluid
detect algorithm is programmed to determine when the at least one
fluid chamber runs out of fluid.
Description
TECHNICAL FIELD
[0001] The disclosure is directed to a digital dispense device
having a pipette-fillable cartridge and in particular to a system
and method for determining the presence or absence of a fluid in a
chamber of a pipette-fillable fluid cartridge.
BACKGROUND AND SUMMARY
[0002] In the medical field, in particular, there is a need for
automated sample preparation and analysis. The analysis may be
colorimetric analysis or require the staining of samples to better
observe the samples under a microscope. Such analysis may include
drug sample analysis, blood sample analysis and the like. Assay
analysis of blood, for example, provides a number of different
factors that are used to determine the health of an individual.
When there are a large number of patients that require blood sample
analysis, the procedures may be extremely time consuming. For assay
analysis, such as drug screenings, it is desirable to deposit
miniscule amounts of target reagents to evaluate their effect and
performance on the samples. Traditionally, pipettes--manually or
electromechanically actuated--are used to deposit trace substances
into these assay samples. The total volume of a test fluid produced
for an assay is dictated by the ability to achieve a desired ratio
of reagents with respect to the least of the reagents. Due to the
small-scale volumetric limitations of pipettes, it is often
necessary to create an excess of testing fluid to achieve the
proper ratio of reagents.
[0003] It is well known that thermal inkjet technology is capable
of precisely distributing picolitre-sized droplets of a jetting
fluid. The precision and speed offered by inkjet technology makes
it a promising candidate for increasing throughput of assay samples
while decreasing the amount of wasted sample. In a conventional
thermal-jet printer, a jetting fluid is typically prefilled into a
printhead before reaching the end-user. However, it is impractical
to use a prefilled cartridge in the life-sciences field where it is
desirable to produce testing solutions on site.
[0004] Accordingly, a pipette-fillable cartridge may be used with
the digital dispense system. Pipette-fillable cartridges are filled
at the time of use with a pre-determined amount of fluid for
performing a chemical assay of a sample. In some cases, the fluid
is to be deposited in a well of a micro-well plate or onto a glass
slide. Since the amount of fluid to be dispensed is critical to the
assay analysis being performed, it is important to know if a fluid
and the right amount of fluid is pipetted into a fluid chamber of a
pipette-fillable cartridge. If the chamber is devoid of fluid, or
prematurely runs out of fluid before the assay is complete, the
sample may be ruined or provide inaccurate results. Accordingly,
what is needed is an apparatus and method for notifying a user that
a fluid chamber of a pipette-fillable cartridge may be devoid of
fluid.
[0005] In view of the foregoing, an embodiment of the disclosure
provides a digital dispense system and method of using a digital
dispense system. The digital dispense system includes a
pipette-fillable fluid cartridge having one or more fluid chambers
therein and having an ejection head attached thereto. The ejection
head contains a plurality of fluid ejectors thereon. The fluid
ejectors are in fluid flow communication with the one or more fluid
chambers of the pipette-fillable fluid cartridge. A fluid detection
circuit is disposed on the ejection head and associated with at
least one of the plurality of fluid ejectors for signaling the
presence or absence of fluid in the one or more fluid chambers.
[0006] In another embodiment, there is provided a method for
dispensing fluid with a digital dispense system. The method
includes providing a pipette-fillable fluid cartridge having one or
more fluid chambers therein and having an ejection head attached
thereto. The ejection head contains a plurality of fluid ejectors
thereon, wherein the fluid ejectors are in fluid flow communication
with the one or more fluid chambers of the pipette-tillable fluid
cartridge. A fluid detection circuit is disposed on the ejection
head and associated with at least one of the plurality of fluid
ejectors for signaling the presence or absence of fluid in the one
or more fluid chambers. At least one of the one or more fluid
chambers is filled with a fluid to be dispensed. A diagnostic
function of the digital dispense system is activated to determine
if the fluid to be dispensed is present in or absent from the at
least one of the one or more fluid chambers. A fluid dispense
sequence is activated in an absence of an error or warning from the
diagnostic function.
[0007] In another embodiment, there is provided a digital dispense
system that includes a pipette fillable cartridge having at least
one fluid chamber therein and an ejection head in fluid flow
communication with the at least one fluid chamber. The ejection
head contains a plurality of fluid ejectors and a fluid detection
circuit thereon. A processor is disposed in the digital dispense
system and is configured with a fluid detect algorithm. The
processor is in electrical communication with the fluid detection
circuit for activating an error signal in the absence of fluid. A
user input device is provided for modifying or terminating a fluid
dispense sequence upon error signal activation.
[0008] In some embodiments, the fluid detection circuit is selected
from (a) a conductivity sense circuit, (b) a thermal sense circuit,
and a combination of (a) and (b). In some embodiments, the
conductivity sense circuit includes a first electrode in electrical
communication with at least one of the plurality of fluid ejectors,
and a second electrode is disposed in a fluid flow path to at least
one of the plurality of fluid ejectors. In other embodiments, the
thermal sense circuit includes a voltage slope detect circuit for
at least one of the plurality of fluid ejectors.
[0009] In some embodiments, the fluid cartridge comprises two or
more discrete fluid chambers.
[0010] In some embodiments, the ejection head comprises two or more
arrays of fluid ejectors thereon and at least one fluid ejector
from each of the two or more arrays of fluid ejectors is associated
with the fluid detection circuit.
[0011] In some embodiments, the fluid dispense sequence is modified
in the presence of an error or warning from the diagnostic function
that indicates an incorrect fluid in the at least one of the one or
more fluid chambers.
[0012] In some embodiments, the fluid dispense sequence is modified
in the presence of an error or warning from the diagnostic function
that indicates that fluid is absent from the at least one of the
one or more fluid chambers.
[0013] In some embodiments, the fluid dispense sequence is
terminated in the presence of an error or warning from the
diagnostic function that indicates that fluid is absent from the at
least one of the one or more fluid chambers.
[0014] In some embodiments, the fluid detect algorithm is
programmed to use (a) fluid conductivity data, (b) ejector thermal
data, or a combination of (a) and (b) to determine if a fluid is
present in the at least one fluid chamber.
[0015] In some embodiments, the fluid detect algorithm is
programmed to (i) use fluid conductivity data initially and to (ii)
use ejector thermal data if fluid is not found by step (i).
[0016] In some embodiments, the pipette-fillable cartridge contains
two or more fluid chambers and the fluid detect algorithm is
programmed to determine if a fluid is absent from a predetermined
one of the two or more fluid chambers.
[0017] In some embodiments, the fluid detect algorithm is
programmed to determine when the at least one fluid chamber runs
out of fluid.
[0018] An advantage of the disclosed embodiments is that it
provides unique low-cost pipette-fillable cartridges that provide
feedback to a user if fluid chambers of the cartridge do not
contain fluid or an incorrect fluid is pipetted into a fluid
chamber. Other advantages of the embodiments enable a user to
determine if the correct amount of fluid was pipetted into a fluid
chamber for a particular analysis job. Feedback provided by the
system disclosed herein may be used to correct errors before
beginning a fluid dispense job.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view, not to scale, of a digital
dispense system according to an embodiment of the disclosure.
[0020] FIG. 2 is a perspective view, not to scale, of a tray and
microwell plate for use with the digital dispense system of FIG.
1.
[0021] FIG. 3 is a perspective view, not to scale, of a
pipette-fillable cartridge for use with the digital dispense system
of FIG. 1.
[0022] FIG. 4 is a plan view, not to scale, of an ejection head for
the pipette-fillable cartridge of FIG. 3.
[0023] FIG. 5 is an enlarged plan view, not to scale of a portion
of an ejector array on the ejection head of FIG. 4.
[0024] FIGS. 6 and 7 are schematic views not to scale of a fluid
detect circuit without and with fluid according to an embodiment of
the disclosure.
[0025] FIG. 8 is a schematic diagram of the fluid detect circuit of
FIGS. 6 and 7.
[0026] FIG. 9 is schematic diagram of a voltage change circuit for
use with the fluid detect circuit of FIGS. 6 and 7.
[0027] FIGS. 10 and 11 are schematic diagrams of thermal detect
circuits according to a second embodiment of the disclosure.
[0028] FIG. 12 is a schematic view of a digital output from the
thermal sense circuits of FIGS. 10 and 11.
[0029] FIG. 13 is block diagram of the digital dispense system of
FIG. 1
[0030] FIG. 14 is a process flow diagram for the fluid sense
circuits according to embodiments of the disclosure.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0031] With reference to FIGS. 1-2 there is shown a digital
dispense device 10 for accurately dispensing an amount of one or
more fluids onto a substrate. Unlike the high-end digital dispense
devices, the device 10 of the present invention is based on an
ejection head that moves back and forth in a first x direction and
a tray 14 for moving a substrate that moves back and forth in a
second y direction orthogonal to the first direction during the
fluid dispense operation. The tray 14 is adaptable to a wide
variety of substrates including, but not limited to, micro-well
plates, glass slides, electronic circuit boards and the like. FIG.
2 illustrates a tray 14 for holding a micro-well plate 38
containing wells 40 therein for use with the digital dispense
device 10 to dispense fluid into the wells 40 of the micro-well
plate or onto the glass slides. The tray 14 may include adapters
for different size micro-well plates or for holding slides or other
substrates for deposit of fluid thereon.
[0032] The dispense head cartridge containing a fluid ejection head
and a cartridge movement mechanism are contained in a rectangular
prism-shaped box 18. An activation switch 20 is included on the box
18 for activating the device 10. A rear side of the box 18 includes
an opening for movement of the tray 14 through the box 18 in the
second direction to dispense fluid onto a substrate. A USB port is
provided on the box 18 to connect the digital dispense system 10 to
a computer or a digital display device. Power is provided to the
system 10 through a power input port on the box 18.
[0033] A pipette-fillable cartridge 50 for use with the digital
dispense device 10 of FIG. 1 is illustrated in FIG. 3. The
cartridge 50 has a molded body 52 that provides one or more open
fluid chambers 54a-54f therein. The fluid chambers 54a-54f are
separated from one another by dividing walls 56A and 56B. Each of
the fluid chambers 54a-54f is associated with a fluid via for
providing fluid to an array of fluid ejectors on an ejection head.
With reference to FIG. 4, an ejection head 60 containing six fluid
vias 62 and associated arrays of fluid ejectors is shown. A greatly
magnified portion of the ejection head 60 is illustrated in more
detail in FIG. 5. Each fluid via 62 provides fluid from one of the
fluid chambers 54a-54f to arrays of fluid ejectors 64 disposed on
one or both sides of the fluid via 62. The fluid ejectors are
located in a fluid ejection chamber 66. Fluid is provided from the
fluid via 62 through a fluid channel 68 to the fluid ejection
chamber 66. Upon activation of the fluid ejector 64, fluid is
dispensed through an ejection nozzle 70 to a substrate which may be
the well 40 of the micro-well plate 38 or to a glass slide.
[0034] In order to determine if the fluid chambers 54a-54f contain
fluid, a fluid detection circuit selected from one or more of a
conductivity sense circuit and/or a thermal sense circuit may be
used. A conductivity detection device 80 is illustrated in a
simplified plan view in FIG. 6 of a single fluid ejection chamber
66 containing electrodes 82 and 84. Electrode 82 may be a tantalum
protective layer disposed over the fluid ejector 64. A second
electrode 84 is disposed in the fluid channel 68 for fluid from the
fluid via 62 to the fluid ejection chamber 66. Each of the
electrodes 82 and 84 may be made of a metal such as tantalum which
is resistant to the fluids dispensed by the digital dispense device
10. Accordingly, any suitable metal may be used as electrodes 82
and 84. At least one electrode 82 and one electrode 84 may be
provided for each array of fluid ejectors 64 on the ejection head
60.
[0035] FIG. 7 shows the conductivity detection device 80 in a
steady state with the fluid chamber 66 and fluid channel 68 filled
with fluid 86. As shown, the first electrode 82 and second
electrode 84 are now fluidly connected by means of a conductive
fluid 86. It is known from electrochemical principles that the
relationship between the fluid and the first and second electrodes
83 and 84 can be represented by an electrical circuit 90 with a
resistor, Rs, representing the solution resistance and the
capacitor, Cd, representing the double layer capacitance formed at
the electrode to fluid interface when biased as shown in FIG. 8. It
should be understood that in the case where a conductive liquid is
not present the double layer capacitor does not exist, and the
series resistance would appear as an open circuit 90.
[0036] In an exemplary embodiment, a voltage step is applied to the
circuit 90 and the resulting response is used to sense the presence
or absence of liquid. An exemplary circuit 92 for making a voltage
change measurement using the conductivity detection device 80 is
illustrated in FIG. 9. The circuit 92 provides a digital high
output when fluid is present in the conductivity detection device
80 and a digital low output when the detection device 80 is devoid
of fluid.
[0037] The circuit 92 may be grouped into seven functional blocks.
The bias block 94 develops a current bias used by the threshold
detection block 96. The sampling block 98 connects the sampling pad
to the sample current mirror 100 when the sense pin is at a high
state. The sample current mirror 100 then replicates the fluid
current sensed and the current flows into the threshold current
detection block 96. If the mirrored current sensed is greater than
the threshold current then fluid is present and the inverter block
102 produces a low state at the input of the latch block 104 and
the latch block detect pin will go to a high state. The latch is
required because of the transient charging nature of the current
that flows through the fluid. If fluid is not present then the
sampled current will be much less (almost zero) than the threshold
detect current. The inverter will then produce a high state which
also produces a low state at the latch detect output. The latch is
a memory element and its state will persist until its sense_reset
pin is forced to a high state. The high state of the sense_reset
pin will clear the latch's detect output pin to a low state. In
summary, a transient current pulse through the fluid causes the
latch to trigger and its detect output pin will be latched at a
high state or the "fluid sensed" state.
[0038] While the foregoing conductivity detection device 80 may be
applied to all of the fluid ejectors in an array of fluid ejectors
64, a single conductivity detection device 80 may be used for each
array of fluid ejectors 64. Accordingly, if fluid is not sensed by
the conductivity detection device 80 for a single array of fluid
ejectors, a warning signal may be sent by a processor in the
digital dispense system to a user as described in more detail
below.
[0039] For fluids that are non-conductive, the conductivity
detection device 80 may not be suitable for detecting the presence
or absence of fluid in a fluid chamber 54a-54f. Accordingly, a
backup fluid detection circuit may also be included on the ejection
head 60. In this embodiment, the fluid ejectors 64 are thermal
fluid ejectors that are used to heat a fluid and create a vapor
bubble in the fluid chamber 66. The formation of a bubble on a
surface of the thermal fluid ejectors is detected based on the
slope change in the current passing through the fluid ejector 64.
If no fluid is present on the surface of the thermal fluid ejector,
the rate at which the surface of the fluid ejector 64 is heated
will increase. By detecting a change in the rate of heating of the
ejector surface, the presence or absence of fluid can be
detected.
[0040] FIG. 10 is a block diagram of thermal sense circuit 200 for
a fluid detection device according another embodiment of the
disclosure. The thermal sense circuit 200 includes a differentiator
212, and A/D converter 214 and a controller 216. The theral sense
circuit 200 is configured to sense the voltage at the drain of the
power FET of the driving element of at least one fluid ejector 64
of a fluid ejector array. In FIG. 10, the fluid ejector 64 is shown
(represented as a resistor) including a corresponding driving
element 204. The driving element 204 is preferably a MOSFET driving
element, including a polysilicon gate 206, source 208, and drain
210. Each driving element is operable to selectively enable the
fluid ejector 64 according to a logic structure provided by a
controller 216 in the digital dispense system 10.
[0041] The differentiator 212 is electrically connected to the
drain 210 of the driving element 204. The differentiator 212 serves
to enhance the small slope change of a voltage that occurs at the
time of fluid bubble formation on the surface of the fluid ejector
64. For example, assume that a fluid ejector 64 having a sheet
resistance of 350 ohms/sqr and a negative temperature coefficient
of -320 ppm is used for the thermal sense circuit 200. At the time
of a bubble formation on the surface of the fluid ejector 64, there
is a slight increase in the slope of the fluid ejector current.
While the slope change is small, it is detectable using a measuring
socilloscope to determine the exact time when the change in fluid
ejector current occurs. The fluid sense circuit 200 senses the
current through the fluid ejector 64 in order to sense bubble
formation.
[0042] In another embodiment, the voltage at the drain of the power
FET is sensed. As with the measured current previously discussed,
the slope change of the voltage is small and is best enhanced by a
differentiation of the value by the differentiator 212. The
differentiator 212 may be any suitable differentiator circuit known
in the art and may include circuit components such as, for example,
capacitors and operational amplifiers.
[0043] The output of the differentiator 212 is sent to the A/D
converter 214, the output of which is then sent to the controller
216. The controller 216 may be configured to remove power from the
heater 202 if no fluid is detected. In this way, the thermal sense
circuit 200 may be used to determine the condition of the fluid
ejector. For example, by programming the controller 216 with preset
values for voltage slope change and times, the thermal sense
circuit 200 can determine whether a voltage slope change actually
occurs, and if so, whether the slope change matches the programmed
value and timing. Any deviation from the programmed values would
indicate that fluid is absent from the surface of the fluid ejector
64.
[0044] The controller 216 may be configured to disable a fire pulse
when the absence of fluid is dectected, or may be configured to
alert the user that the fluid chamber 54a-54f is devoid of fluid.
In this regard, when a slope change is detected, the differentiator
212 may output a logic high or digital 1. When this value is
inverted and then ANDed with the fire pulse the result is that the
signal is gated and the power FET device is turned off.
[0045] FIG. 11 is a block diagram of an alternative thermal sense
circuit 300 for a fluid detection circuit according another
exemplary embodiment of the disclosure. The thermal sense circuit
300 includes a sampling circuit 310 and a slope detect circuit
differentiator 312. As shown, the voltage is sampled at the
transistor drain node as described above, but in the present
embodiment the drain voltage is passed as an input to the sampling
circuit 310. The sampling circuit 310 can be a switched capacitor
circuit with an analog output or an A/D circuit with a digital
output. The output value from the sampling circuit 310 is fed into
the slope detect circuit differentiator 312 which performs a sample
to sample differentiation of the signal. A sudden change in slope
is detected within the slope detect circuit differentiator 312 and
converted to a digital output 314 as shown in FIG. 12. As in the
previous embodiment, the slope detect circuit differentiator 312
may output a logic high or digital 1 which is used to turn the
power MOS FET off and signal the user that the fluid chamber is
devoid of fluid.
[0046] It will be appreciated that one or both of the fluid detect
circuits may be used for the pipette-fillable cartridge 50
described above. The fluid detect circuits may be used individually
or seqentially, or the system may be programmed to use one fluid
detect circuit for one fluid and a different fluid detect circuit
for a different fluid. In some embodiments, a conductivity detect
circuit may be used first to detect the presence or absence of
fluid, and if no fluid is detected, a thermal sense circuit will
then be used to detect the presence or absence of fluid. If one or
more fluid chambers 54a-54f contain fluid, the fluid will flow into
the ejection head 60 from the fluid via 62 to fill the fluid
channel 68 and fluid chamber 66. Upon activation of the fluid
ejector 64, fluid will then be ejected through the fluid nozzle 70
to a substrate such as the well of the micro-well plate or onto a
glass slide. If no fluid is present in the fluid chamber, then the
fluid detect circuit will be activated to notify the user of a
problem.
[0047] FIG. 13 is a block diagram of a digital dispense system 10
having a user input block 400 for inputting fluid information,
fluid chamber information, fluid dispense location, fluid dispense
volume, fluid chamber volume, and substrate type into a memory 410
of the device 10. The processor 412 is configured with an algorithm
that uses the memory information and feedback from the fluid
detection circuits 80, 200 or 300 to control the fluid ejectors 64
on the ejection head 60.
[0048] As shown in FIG. 14, a first step 416 of the process 414 of
dispensing fluid by the digital dispense device 10 is to fill one
or more fluid chambers 54a-54f with fluid using a pipette. The user
also specifies the fluid chamber(s) that contain fluid and the
identification of which fluid is in which fluid chamber in step
418. Once the information is stored in the memory 410 (FIG. 13),
step 420 is initiated either manually or automatically to detect
whether or not fluid is present in the specified fluid chamber(s)
using one or both of the fluid detect circuits described above. If
the fluid is conductive, then the processor activates the
conductivity detection device 80 to determine if fluid is present.
If no fluid is detected because the specified fluid chamber(s) is
empty or the fluid is non-conductive, then the processor activates
the thermal sense circuit 200/300 to determine if fluid is present
in the specified fluid chamber(s). If fluid is detected in the
correct fluid chambers in step 422, then the dispense job commences
in step 424 until the job is complete and terminated in step 430.
However, if there is no fluid present in the specified fluid
chamber(s) or the fluid is determined to be in the incorrect fluid
chamber(s), an error signal is provided in step 426 requiring the
user to intervene in the process in step 428. The user may
terminate the dispense job in step 430, or correctly fill the
chambers in step 416 and/or specify which fluid is in which chamber
in step 418.
[0049] For example, if fluid is supposed to be pipetted into fluid
chamber 54a and the user mistakenly pipettes fluid into fluid
chamber 54b, the fluid detection circuit can detect that fluid
chamber 54a is devoid of fluid and can detect that chamber 54b
contains fluid. The processor can display a warning that an error
occurred and allow the user to fix the error before proceeding to
step 424. In the alternative, the processor can be programmed to
virtually move the fluid data from fluid chamber 54a to fluid
chamber 54b automatically or upon input by the user. The process or
could also be programmed to continuously check for fluid in each of
the fluid chambers during the dispense operation to determine if a
chamber runs out of fluid before the fluid dispense operation is
complete. Information about the amount of fluid used and the
history of fluid ejected from individual fluid chambers may be
stored in the memory for future reference or for troubleshooting
fluid dispense operations.
[0050] It is noted that, as used in this specification and the
appended claims, the singular forms "a," "an," and "the," include
plural referents unless expressly and unequivocally limited to one
referent. As used herein, the term "include" and its grammatical
variants are intended to be non-limiting, such that recitation of
items in a list is not to the exclusion of other like items that
can be substituted or added to the listed items.
[0051] While particular embodiments have been described,
alternatives, modifications, variations, improvements, and
substantial equivalents that are or can be presently unforeseen can
arise to applicants or others skilled in the art. Accordingly, the
appended claims as filed and as they can be amended are intended to
embrace all such alternatives, modifications variations,
improvements, and substantial equivalents.
* * * * *