Object of the Invention
[0001] The present invention is an apparatus for controlling the flow rate in a specific
segment in a microfluidic device. This apparatus is formed by a first interrelated
product provided in the form of a portable device comprising microfluidic channels
and a second interrelated product provided in the form of a control apparatus suitable
for receiving the first portable device.
[0002] The first portable device comprises at least one plate with at least one open microfluidic
channel segment configured on the surface of the plate. On this microfluidic channel
segment, there is a thermally conductive sheet closing the open microfluidic channel,
said thermally conductive sheet comprising a region on the outer surface receiving
a thermal sensor. The same microfluidic channel segment comprises a microvalve, either
upstream from the thermal sensor or downstream from the thermal sensor, covered by
a flexible sheet, which regulates flow in the microfluidic channel segment depending
on the pressure exerted on the flexible sheet.
[0003] The invention allows regulating flow in the microfluidic channel segment by establishing
a flow rate according to a setpoint value in the control apparatus with a closed loop
regulation between the signal from the thermal sensor and the microvalve.
Background of the Invention
[0004] Today, one of the technical fields being more intensively developed is the field
of microfluidic devices called
Lab-on-a-Chip. These devices are made up of a plate comprising chambers and microfluidic channels,
also called microchannels, where experiments giving rise to results which would otherwise
require laboratory testing are carried out. These devices are usually disposable.
[0005] Some experiments require incorporating reagents, measuring specific variables according
to the progress of a fluid sample through microfluidic channels; and particularly,
there are experiments which require establishing a specific flow rate.
[0006] In the latter cases, very small flow meters capable of measuring low flows are known.
Nevertheless, although they are capable of measuring very low flow rates, they are
not devices that can be incorporated in a microfluidic device and what is done is
that these devices are arranged either coupled to an inlet port or an outlet port,
and always outside the microfluidic device. Nevertheless, these micro-flow meters
only measure flow rate and do not provide a control which determines a specific flow
rate value according to a setpoint value.
[0007] There are micro-flow meters which measure flow rate by incorporating thermal sensors.
These thermal sensors are formed by a plurality of electrodes located inside the channel
through which the fluid passes. Several of those electrodes heat up when they are
powered, increasing the temperature of the fluid they are in contact with. Other electrodes
act as temperature sensors measuring the temperature upstream as well as downstream
from the electrodes that provide heat. Depending on the flow rate, in response to
one and the same heat supply, the temperature increase measured in the flow will be
greater or less. It is possible to establish a correlation between the temperature
increase between the groups of electrodes intended for the reading upstream and downstream
and the flow passing through the electrodes determining the flow rate.
[0008] Nevertheless, in any case the electrodes are located in the channel so that they
can contact with the fluid the flow rate of which is to be evaluated. This condition
makes the known flow meters devices that must be incorporated in the specific place
for which the support of the microfluidic channel has been jointly designed.
[0009] The present invention establishes a combination of a sensor suitable for measuring
flow rate in a microfluidic channel segment and a microvalve, locating the electrodes
outside the channel. This not only allows integration at a specific point of the microfluidic
device, particularly at an intermediate point of the microfluidic path, without the
latter having to be located in an inlet port or outlet port; it also allows establishing
control over said flow rate according to a pre-established setpoint value.
[0010] A second technical advantage of the electrodes being located in the control apparatus
suitable for receiving the microfluidic device is the portable microfluidic device
cost reduction. If said portable microfluidic device is disposable, the electrodes
are only necessary in the control apparatus and are used for taking measurements in
a plurality of microfluidic devices instead of having to incorporate as many thermal
sensors as disposable devices.
Description of the Invention
[0011] The present invention is an apparatus for controlling the flow rate in a specific
segment in a microfluidic device. This apparatus is formed by a first interrelated
product provided in the form of a portable device comprising microfluidic channels,
typically a so called
Lab-on-a-Chip device, and a second interrelated product provided in the form of a control apparatus
suitable for receiving the first portable device. This second control apparatus acts
on the former, i.e., the portable device, establishing a specific flow rate in a pre-established
microfluidic channel segment.
[0012] According to various embodiments, the same control apparatus is capable of establishing
a pre-established flow rate in different microfluidic channel segments of the portable
device, where these segments in which a specific flow rate is regulated can be intermediate
segments between chambers or between other elements and do not have to be in direct
contact with the fluid inlet and the fluid outlet of the microfluidic device.
[0013] The first interrelated product for controlling the flow rate in a microfluidic device
is provided in the form of a portable device and it comprises:
- a support plate with at least one open microfluidic channel segment configured on
the surface of the plate;
- a first thermally conductive membrane attached to the support plate such that it covers
the at least one microfluidic channel segment such that said microfluidic channel
segment is closed by the first membrane.
[0014] The portable device giving rise to the first interrelated product is formed primarily
by a plate. This plate can internally contain chambers and channels depending on the
functions to be performed by the portable device. It particularly comprises an open
channel segment, i.e., it is a channel with walls which are intended for guiding the
flow of a fluid sample but the section thereof is not a closed trajectory. The open
channel segment can be accessed from outside before being covered by the first membrane.
This first membrane covers the open channel segment, extending over the outer surface
of the plate containing the channel. A particular way of applying this first membrane
is by attaching it to the plate by means of an adhesive. The first membrane extends
over the surface of the plate and particularly covers the open channel segment resulting
in a closed channel. -
a region on the outer surface of the first conductive membrane, where the side opposite
said region is in contact with at least part of the microfluidic channel segment,
suitable for receiving a thermal flow sensor.
[0015] The first sheet closing the open channel segment is a thermally conductive sheet.
A region of the outer surface of the first sheet where the side opposite said region
is in contact with at least part of the microfluidic channel segment is the region
that will allow the reading of the flow rate passing through the microchannel segment.
A thermal sensor is arranged on this region. In one embodiment, this sensor has electrodes
to generate heat. The heat is transmitted to the fluid since the first sheet is thermally
conductive. The thermal sensor also has electrodes for the reading of the temperature
upstream and downstream, with respect to the direction of the flow passing through
the microfluidic channel segment, of the electrodes that provide heat to the fluid.
Although the sheet is thermally conductive, it establishes a barrier against the passage
of heat that can prevent the correct reading of the flow rate with the applied dimensions
of a microchannel. Despite having located the electrodes outside the microchannel
leaving the membrane as an intermediate barrier between the electrodes and the fluid
passing through the microfluidic channel, it has been proven experimentally that the
solution of incorporating the electrodes outside the sheet does not prevent the correct
reading of the flow rate.
[0016] According to different embodiments, the electrodes which are located on the region
of the surface belong to either the portable device or to the machine responsible
for controlling the portable device. In the first case, the electrodes can be electrodes
deposited by means of sputtering, evaporation, screen printing, jet printing or a
combination of any of them. They can also be electrodes deposited on a second, for
example, adhesive sheet which is incorporated and attached to the outer surface of
the first thermally conductive sheet. In this second solution, the placement of the
first sheet only requires the channels to be well closed without the position requirements
applied by the electrodes being located on this first sheet. The second sheet does
not have to cover the area of the first sheet entirely, so the placement of the second
sheet containing the electrodes only has to assure a correct positioning with respect
to the region on the outer surface of the first conductive membrane intended for receiving
the electrodes.
- a microvalve where:
∘ said microvalve is configured according to an open cavity on the surface of the support
plate,
∘ the open cavity has a microfluidic inlet and a microfluidic outlet,
∘ the open cavity is covered by a flexible membrane such that it has a region of its outer surface suitable for receiving a pressure actuator such
that the pressure on said region causes the deformation of the flexible membrane and
the closure of the microvalve,
where either the inlet or the outlet of said microvalve is in fluidic connection with
the microfluidic channel segment.
[0017] The flow rate on the microfluidic channel segment is regulated by acting on a microvalve
which is in microfluidic communication with said segment either upstream or downstream.
The microvalve is formed by an open cavity, open being interpreted as a configuration
identical to that of the open channel segment, where the open cavity will be closed
because a flexible membrane covers it, extending over the outer surface of the support
plate where the open cavity is located.
[0018] The action of a pressure actuator on the outer surface of the membrane, given that
the membrane is elastic, causes the deformation of the membrane segment which is covering
the cavity. The deformation causes the membrane to invade the space of the cavity,
making the space of the chamber forming said cavity smaller, particularly the space
through which the inflow, the outflow, or both, passes. A particular way of closing
this space is by the membrane resting on the opening making up the inlet or outlet
of the cavity of the microvalve. The variation in the deformation of this membrane
gives rise to greater or less restriction to the passage of fluid.
[0019] The closed loop regulation between the flow rate measured in the thermal sensor and
the actuation on the microvalve establishes a flow rate passing through the microfluidic
channel segment according to the setpoint value of the closed loop.
[0020] The invention also has a second interrelated product provided in the form of a control
apparatus. This control apparatus is suitable for receiving the portable device such
that it is capable of reading the flow in the microfluidic channel segment having
a region suitable for receiving the thermal sensor and of acting on the microvalve
regulating the flow in accordance with a pre-established setpoint value.
[0021] This control apparatus comprises:
- a fixing support for fixing a portable device,
- an actuator suitable for exerting pressure on the region of the outer surface of the
flexible membrane located such that that it is covering the microvalve of the portable
device once fixed in the fixing support and which is suitable for receiving a pressure
actuator,
- or a thermal sensor suitable for contacting with the region on the outer surface of
the first conductive membrane of the portable device once fixed in the fixing support;
or if the portable device already has a sensor, means for contacting with said sensor
when the portable device is fixed in the fixing support.
[0022] The control apparatus receives the portable device in a fixing support. The fixing
support determines the position where either the region of the first membrane where
the thermal sensor has to be located or the electrodes of the thermal sensor, if the
portable device has said thermal sensor, are located. In the first case, the thermal
sensor is arranged in the control apparatus in a position such that the thermal sensor
is in contact with the first thermally conductive membrane on the region suitable
for receiving the thermal sensor.
[0023] The same occurs with the microvalves. The positioning determined by the fixing support
allows locating the actuator, which is intended for pressing on the microvalve to
regulate its opening or closure, on the portion of flexible membrane intended for
allowing the actuation of the pressure actuator.
- a central processing unit:
∘ comprising signal input from the thermal sensor where said central processing unit
is suitable for determining the flow rate passing through the at least one microfluidic
channel segment based on the input signal,
∘ comprising an outlet in connection with the actuator for controlling the microvalve,
∘ comprising an inlet for establishing a setpoint flow rate value in the at least one
microfluidic channel segment; and
∘ where the central processing unit has a closed loop configuration for regulating the
flow rate by means of the microvalve in order to reach the setpoint value.
[0024] The central processing unit coordinates at least the reading of the flow rate by
means of the thermal sensor and the actuation on the actuator, establishing the degree
of opening or closure of the microvalve according to a closed loop scheme. According
to various embodiments, this same central processing unit can manage a plurality of
sensors and valves such that the closed loop regulation can be carried out on a path
containing a thermal sensor, a valve, closing the remaining valves such that the mentioned
path is established.
Description of the Drawings
[0025] The foregoing and other advantages and features of the invention will be better understood
from the following detailed description of a preferred embodiment provided only by
way of illustrative and non-limiting example in reference to the attached drawings.
Figure 1 shows an elevational view and plan view of a microfluidic device according
to a first embodiment comprising a channel on which a specific flow is to be established,
a channel segment with a thermal sensor for reading the flow rate, a bypass segment
for increasing the flow which the microfluidic device is capable of regulating; and
a microvalve. The elevational view is shown right below the plan view with the membrane
located slightly away from the plate in order to distinguish both elements.
Figure 2a shows a first embodiment of a microvalve with a mechanical actuator.
Figure 2b shows a second embodiment of a microvalve with a pneumatic actuator.
Figure 3 shows a perspective view of an embodiment of an open channel segment, closed
by means of a thermally conductive sheet on which the part of the electrodes which
is active in the reading of the flow rate is shown.
Figure 4 is a diagram showing an embodiment of a control apparatus suitable for receiving
a portable device such that, once said portable device is introduced in the control
apparatus, it is possible to establish a specific flow rate in a microfluidic channel
segment in said portable device.
Figure 5 shows a diagram of an embodiment of a portable device comprising a drive
pump, arranged such that it is either integrated in the portable device or is outside
said portable device, the outlet of which is in fluidic communication with three segments,
each of them comprising a sensor and a valve. In this embodiment, it is possible to
regulate the flow in any of the three branches of the portable device.
Figure 6 shows a diagram of an embodiment of a portable device comprising two possible
inlets and a single outlet. In this embodiment, the fluid inlet is selected and flow
regulation is carried out on this inlet.
Figure 7 shows a diagram of an embodiment of a portable device comprising a single
fluid inlet and two branches opening into respective outlets. In this embodiment,
the fluid outlet is selected and flow regulation is carried out on the branch opening
into said outlet.
Figure 8 shows a graph in which three curves are superimposed on one another. The
curve shown with a continuous line is a step function with the setpoint flow value
applied to a control apparatus acting on a portable device. The curve shown with a
dash line is the flow response obtained when applying the setpoint value in an embodiment
of the invention obtaining the reading by means of a thermal sensor according to the
invention arranged on the thermally conductive membrane. The curve shown with a dotted
line is the response to the flow measured using a commercial micro-flow meter.
Detailed Description of the Invention
[0026] According to the first inventive aspect, the present invention is an apparatus formed
by a first interrelated product and a second interrelated product. The first interrelated
product is the portable device (1) and the second interrelated product is the control
apparatus (2) receiving the portable device (1) for acting on said device (1), assuring
the passage of a flow rate pre-established as a setpoint value in at least one microfluidic
channel segment (1.4).
[0027] The elevational view shown in the bottom part of Figure 1 shows the plate (1.1) in
which there are located microfluidic channels and other cavities such as those which
give rise to a microvalve (1.6), and a membrane (1.2) located away from the plate
(1.1).
[0028] In this embodiment, the membrane (1.2) is a thermally conductive sheet and is furthermore
flexible. The same membrane (1.2) thus allows establishing the closure of the microfluidic
channel segment (1.4) on which the thermal sensor (1.7.1) is arranged as well as the
closure of the cavity of the microvalve (1.6) with the flexibility which allows regulating
the degree of opening of said microvalve (1.6) by the deformation it sustains according
to the pressure exerted thereon. In this embodiment, the membrane (1.2) extends over
a face of the plate (1.1) and is attached thereto by means of an adhesive.
[0029] In the plan view shown in the top part of Figure 1, an inlet to a microfluidic channel
(1.3) is seen on the left, following the orientation of the drawing. By combining
the plan view and the elevational view, it is observed that this inlet comes from
a channel segment arranged perpendicular to the plate such that it opens into an open
channel running parallel to the surface and limited by the membrane (1.2).
[0030] In turn, the section of the open channel expands giving rise to two channel segments,
a narrow first channel segment (1.4) and a wide second channel segment configured
as a bypass (1.5). In this embodiment, the flow to be regulated is high. In the narrow
first channel segment (1.4), there is arranged a thermal sensor (1.7.1) located on
the membrane (1.2). The reading of the flow rate in the narrow channel segment (1.4)
determines the flow rate in the channel segment (1.5) configured as a bypass given
that the section ratio is known. This particular way of configuring a channel segment
as a bypass having a larger section allows a precise reading by means of a thermal
sensor since the reading continues to be taken in a microfluidic channel having a
small section, and it allows the passage of high flow rates for a microfluidic device.
[0031] The thermal sensor (1.7.1) is formed by three electrode segments arranged on the
membrane (1.2) as shown in detail in the embodiment shown in Figure 3. A central electrode
produces a pre-established amount of heat when current is passed through it. The heat
it produces is transferred to the flow passing through the channel through the membrane
(1.2) since it is conductive for the passage of heat. The electrodes arranged on the
sides of this electrode intended for generating heat allow the reading of the temperature
before and after supplying the heat. The temperature difference will be less the greater
the flow passing through the channel. The correlation between this temperature difference
and the flow rate allows measuring the flow rate passing through the microfluidic
channel located below the thermal sensor (1.7.1).
[0032] Figure 1 shows conductive tracks (1.7) located on the membrane (1.2) establishing
electrical communication between the power supply contacts and the reading, and the
three electrodes acting as a thermal sensor (1.7.1) which are located on the microfluidic
channel.
[0033] According to one embodiment, the conductive tracks (1.7), and particularly the electrodes
acting as a thermal sensor (1.7.1), are arranged on an adhesive sheet other than the
membrane (1.2) and held thereon such that the electrodes acting as a thermal sensor
(1.7.1) are suitably positioned on the microfluidic channel in which the flow rate
is measured.
[0034] According to another embodiment, the conductive tracks, (1.7) and particularly the
electrodes acting as a thermal sensor (1.7.1), are deposited by means of sputtering,
evaporation, screen printing, jet printing or a combination of any of them.
[0035] The flow from the microfluidic channel segment (1.4) and the flow from the bypass
(1.5) converge again in a channel opening into the microvalve (1.6). This microvalve
(1.6) is configured by means of a cavity (1.6.3) with the inlet (1.6.1) opening into
it. The outlet (1.6.2) is arranged at the bottom of the cavity (1.6.3) where, in this
embodiment, the bottom shows a concavity.
[0036] The membrane (1.2) is pressed on its outer face by an actuator (3, 4) that exerts
pressure. In the embodiment shown in Figure 2a, the actuator is a bar ending in a
blunt surface and is adapted to the concavity of the bottom of the cavity (1.6.3).
As it moves down, always according to the orientation shown in the drawing, penetrating
the cavity (1.6.3), it forces the deformation of the membrane (1.2) which also moves
down, making the space that allows the passage of the fluid through the outlet (1.6.2)
smaller. In an extreme case, the membrane (1.2) rests on the concavity completely,
establishing complete closure. Said Figure 2a shows a first position identified as
i), where the actuator (3) does not press on the membrane (1.2), leaving the microvalve
(1.6) open; a second intermediate position identified as ii), where the actuator (3)
presses on the membrane (1.2), leaving the microvalve (1.6) partially open; and a
third position identified as iii), where the actuator (3) presses on the membrane
(1.2), leaving the microvalve (1.6) closed.
[0037] In the embodiment shown in Figure 2b, the actuator is formed by a chamber (4) having
a support (4.1) to achieve the leak-tight closure when it presses on the membrane
(1.2) externally; and having a conduit (4.2) for injecting a gas, compressed air,
for example. The pressure of the gas causes the membrane (1.2) to move down, said
membrane being deformed and causing the closure of the microvalve (1.6) to a greater
or lesser extent. In this embodiment, the degree of opening of the microvalve (1.6)
is regulated by managing the pressure introduced in the chamber (4) of the actuator.
[0038] Figure 4 schematically shows a portable device (1) which is introduced in the control
apparatus (2). Once introduced and located in the control apparatus (2), the portable
device (1) is positioned on the fixing support of the control apparatus (2) where
said apparatus (2) has at least one sensor module (S) reading the flow rate through
the thermal sensor (1.7.1). The sensor module (S) has means for reading the value
provided by the thermal sensor (1.7.1), or if there are several, it has means for
reading each of them.
[0039] It also has at least one actuator module (A) acting on at least one microvalve (1.6)
of those microvalves arranged in a microfluidic channel segment (1.3) for regulating
the pre-established flow rate by introducing a setpoint value in the control apparatus
(2). Likewise, if there are several microvalves (1.6), the actuator module (A) is
capable of acting on each of them in a different manner.
[0040] A central processing unit (CPU) receives the signal coming from the at least one
sensor module (S) and acts on the at least one actuator module (A) according to a
closed loop regulation. In other words, with respect to a setpoint value, this setpoint
value is compared with the value of the flow read by means of the sensor module (S).
If the value of the read flow rate is greater than the setpoint value, then the degree
of actuation of the actuator (3, 4) which closes the microvalve (1.6) is increased.
In contrast, if the value of the read flow rate is less than the setpoint value, then
the degree of actuation of the actuator (3, 4) which closes the microvalve (1.6) is
reduced to allow greater flow passage.
[0041] Figure 5 shows a diagram of microfluidic channels and components according to one
embodiment. In this embodiment, the portable device is powered by drive means (B).
The drive means are either integrated in the microfluidic device or are located outside
the portable device. The outlet of the drive means (B) is in fluidic communication
with three microfluidic channels, each of which comprises a microvalve (1.6) and a
thermal sensor (1.7.1) therein.
[0042] For each of the microfluidic channels, the control apparatus (2) carries out a closed
loop control by means of reading the flow rate on the microfluidic channel and acting
on the microvalve (1.6) located in the same channel.
[0043] According to one embodiment, the control unit (CPU) processes in parallel a regulation
over each of the channels such that it is possible to pre-establish a different flow
rate for each channel in a different manner.
[0044] According to another embodiment, the control unit (CPU) processes a single closed
loop control over one of the channels and keeps the other microvalves (1.6) closed
by means of the actuator module (A).
[0045] In any case, the drive means can be a pump or a source of constant-pressure flow.
[0046] Figure 6 shows a diagram of microfluidic channels and components according to another
embodiment. In this embodiment, the portable device is fed by two different fluid
inlets. Each of the fluid inlets has a microvalve (1.6). The outlet of each of the
microvalves (1.6) is in communication with a single channel having a sensor (1.7.1).
This channel is the outlet.
[0047] This diagram can be generalized with a plurality of inlets, each of them with a microvalve
(1.6) communicating with the sensor (1.7.1).
[0048] In this embodiment, the control apparatus (2) comprises a central processing unit
(CPU) which is suitable for establishing the closure of all the microvalves (1.6)
except for one of them, leaving only one possible path and therefore only one fluid
inlet. The same central processing unit (CPU) establishes the regulation of the channel
following the only possible path by means of the reading of the flow rate in the sensor
(1.7.1) and the actuation on the microvalve (1.6) which is not necessarily closed.
[0049] Figure 7 shows another embodiment in which there is a common fluid inlet for two
channels. The channel segment corresponding to the common inlet has a main microvalve
(1.6) and each channel starting from this common inlet comprises a thermal sensor
(1.7.1) and a microvalve (1.6).
[0050] This scheme can be generalized by increasing the number of the channels from two
to a plurality of channels fed by the same inlet.
[0051] The control apparatus suitable for controlling the portable device in accordance
with this microfluidic scheme carries out a control closing all the microvalves located
in the individual microfluidic channels fed by the common inlet, except for a pre-established
one. The open valve defines a single microfluidic path the flow rate of which is determined
with a closed loop control using the main microvalve (1.6) and the sensor (1.7.1)
arranged in the channel the microvalve (1.6) of which is open.
[0052] As far as control of the examples shown in Figures 5, 6 and 7 is concerned, the valve
configuration can be changed defining another alternative path, and therefore the
sensor (1.7.1) and microvalve (1.6) combination with which closed loop control is
performed can also be changed.
[0053] The manufacture of electrodes which are deposited on the outer face of the membrane
(1.2) allows locating the sensing and control of the flow in any part of the microfluidic
device or even in a plurality of sites preventing the design of inlet ports and outlet
ports for coupling dedicated devices for measuring or controlling the flow rate.
[0054] Another object of this invention is the combination of a portable device and of the
apparatus suitable for acting on said portable device when the configuration of the
portable device is compatible with the control apparatus.
[0055] At least one experiment has been conducted where the response and flow rate regulation
capacity in a microchannel according to the invention is tested in a laboratory. The
experiment consists of establishing on the microchannel a flow determined by a setpoint
value following an increasing step function.
[0056] Figure 8 shows the increasing function according to step segments with a continuous
line. The response to the flow rate has been measured experimentally by means of two
methods, a first method using the signal obtained in the thermal sensor of the actual
thermal sensor of the portable device and a second method using a commercial flow
meter arranged at the outlet of the portable device incorporated as a device in series
with the outlet of the microchannel.
[0057] Figure 8 shows the response obtained according to the first method with a dash line
and the response measured by means of the second method with a dotted line.
[0058] In both cases, it is observed that the flow rate adheres to the setpoint function
with a high degree of fit. The two measurement values are different, giving a rather
high degree of inertia in the invention possibly due to the thermal barrier established
by the membrane (1.2). Nevertheless, this difference has been found to be acceptable
for the intended applications of the invention.
1. A first interrelated product for controlling the flow rate in a microfluidic device,
provided in the form of a portable device (1) comprising:
- a support plate (1.1) with at least one open microfluidic channel segment (1.4)
configured on the surface of the support plate (1.1);
- a first thermally conductive membrane (1.2) attached to the support plate (1.1)
such that it covers the at least one microfluidic channel segment (1.4) such that
said microfluidic channel segment (1.4) is closed by the first conductive membrane
(1.2);
- a region on the outer surface of the first conductive membrane (1.2), where the
side opposite said region is in contact with at least part of the microfluidic channel
segment (1.4), suitable for receiving a thermal flow sensor (1.7.1);
- a microvalve (1.6) where:
∘ said microvalve (1.6) is configured according to an open cavity (1.6.3) on the surface
of the support plate (1.1),
∘ the open cavity (1.6.3) has a microfluidic inlet and a microfluidic outlet (1.6.1,
1.6.2),
∘ the open cavity (1.6.3) is covered by a flexible membrane (1.2) such that it has
a region of its outer surface suitable for receiving a pressure actuator (3) such
that the pressure on said region causes the deformation of the flexible membrane (1.2)
and the closure of the microvalve (1.6),
where either the inlet or the outlet (1.6.1, 1.6.2) of said microvalve (1.6) is in
fluidic connection with the microfluidic channel segment (1.4).
2. The first product according to claim 1, where the thermal flow sensor (1.7.1) is configured
by means of electrodes (1.7) located on the region of the outer surface of the first
thermally conductive membrane (1.2).
3. The first product according to claim 2, where the electrodes (1.7) located on the
region of the outer surface are electrodes deposited by means of sputtering, evaporation,
screen printing, jet printing or a combination of any of them.
4. The first product according to claim 1, where the thermal flow sensor (1.7.1) is configured
by means of a second sheet containing the electrodes (1.7) configuring the sensor
(1.7.1) on one of its surfaces and said second sheet is fixed on the region on the
outer surface of the first conductive membrane (1.2) suitable for receiving a thermal
flow sensor (1.7.1) such that the electrodes (1.7) are in contact with the first thermally
conductive sheet (1.2).
5. The first product according to claim 1, where the first thermally conductive membrane
attached to the support plate and the flexible membrane covering the open cavity of
the microvalve is one and the same flexible and thermally conductive membrane (1.2).
6. The first product according to claim 1, where either the inlet or the outlet (1.6.1,
1.6.2) of said microvalve (1.6) starts from the base of its open cavity (1.6.3), being
arranged opposite the elastic membrane (1.2) such that the closure of the microvalve
(1.6) is established by the membrane (1.2) deformed by the action of the pressure
actuator (3) resting on the base of the cavity (1.6.3) where the inlet or outlet (1.6.1,
1.6.2) is located.
7. The first product according to claim 1, where the support plate (1.1) comprises a
bypass microchannel (1.5) fluidically communicating the inlet to the at least one
open microfluidic channel segment (1.4) configured on the surface of the support plate
(1.1) with its outlet for controlling a flow rate in the microfluidic device so that
it is equal to the flow rate of the at least one microfluidic channel segment (1.4)
plus the flow rate of the bypass microchannel.
8. The first product according to any of the preceding claims, where the microfluidic
device comprises a plurality of microvalves (1.6), each of them with the inlet suitable
for receiving a fluid, and the plurality of outlets of the microvalves (1.6) in fluidic
connection with the inlet of the at least one microfluidic channel segment (1.4) having
the region for measurement by means of a thermal sensor (1.7.1).
9. The first product according to any of claims 1 to 7, where the microfluidic device
comprises:
- a plurality of microfluidic channel segments (1.4) each of them with a region for
measurement by means of a thermal sensor (1.7.1) and a microvalve (1.6);
- a main fluid inlet; and
where the main inlet is in fluidic connection with the plurality of microfluidic channel
segments (1.4).
10. The first product according to any of claims 1 to 7, where the main inlet comprises
a main microvalve (1.6) after which it is in fluidic connection with a plurality of
microfluidic channel segments (1.4) each of which comprises a region for measurement
by means of a thermal sensor (1.7.1) and a microvalve (1.6).
11. A second interrelated product for controlling the flow rate in a microfluidic device,
provided in the form of a control apparatus (2) comprising:
- a fixing support for fixing a portable device (1),
- an actuator (3) suitable for exerting pressure on the region of the outer surface
of the flexible membrane (1.2) located such that it is covering the microvalve (1.6)
of the portable device (1) once fixed in the fixing support and which is suitable
for receiving a pressure actuator (3),
- or a thermal sensor (1.7.1) suitable for contacting with the region on the outer
surface of the first conductive membrane (1.2) of the portable device (1) once fixed
in the fixing support; or if the portable device (1) already has a sensor (1.7.1),
means for contacting with said sensor (1.7.1) when the portable device (1) is fixed
in the fixing support; and
- a central processing unit (CPU):
∘ comprising signal input from the thermal sensor (1.7.1) where said central processing
unit (CPU) is suitable for determining the flow rate passing through the at least
one microfluidic channel segment (1.4) based on the input signal,
∘ comprising an output in connection with the actuator (3) for controlling the microvalve
(1.6),
∘ comprising an input for establishing a setpoint flow rate value in the at least
one microfluidic channel segment (1.4); and
∘ where the central processing unit (CPU) has a closed loop configuration for regulating
the flow rate by means of the microvalve (1.6) to reach the setpoint value.
12. The second product according to claim 11, where:
- the fixing support is suitable for receiving a portable device (1) according to
claim 8;
- it comprises as many actuators (3) suitable for exerting pressure as microvalves
(1.6); and
where the central processing unit (CPU) comprises signal input in communication with
the thermal sensor (1.7.1) and is suitable for establishing a closed loop between
the thermal sensor (1.7.1) and a pre-established microvalve (1.6) as well as the closure
of the remaining microvalves (1.6).
13. The second product according to claim 11, where:
- the fixing support is suitable for receiving a portable device (1) according to
claim 9;
- it has as many actuators (3) suitable for exerting pressure as microvalves (1.6);
and
where the central processing unit (CPU) comprises as many signal inputs as thermal
sensors (1.7.1) comprised in the portable device (1) and is suitable for establishing
as many closed loops between the thermal sensor (1.7.1) and the microvalve (1.6) arranged
in the same microfluidic channel segment as microvalves (1.6) comprised in the portable
device (1).
14. The second product according to claim 11, where:
- the fixing support is suitable for receiving a portable device (1) according to
claim 10;
- it has as many actuators (3) suitable for exerting pressure as microvalves (1.6),
both for the microfluidic channel segments (1.4) and for the main microvalve (1.6);
and
where the central processing unit (CPU) comprises as many signal inputs as thermal
sensors (1.7.1) comprised in the portable device (1) in its channel segments and is
suitable for establishing a closed loop between a specific thermal sensor (1.7.1)
and the main microvalve (1.6) arranged in the microfluidic channel segment where the
thermal sensor (1.7.1) is located, as well as the closure of the remaining microvalves
(1.6) located in the microfluidic channel segments (1.4).
15. A system comprising a combination of a second interrelated product (2) according to
any of claims 11 to 14 and a first interrelated product (1), compatible with the second
interrelated product (2), according to any of claims 1 to 10.