FIELD OF INVENTION
The present invention relates to an improved valveless micropump with
dome shaped dielectric elastomer diaphragm, pumping chamber and nozzle diffuser
as flow control element. More particularly, the invention relates to a valveless
diffuser type reciprocating displacement pump for delivering fluid in microlevel for
various applications like drug delivery system, chip cooling, micro-propulsion,
chemical delivery. It can also be used in the field of chemical dosing to deliver drop
wise pulsed fluid, as it can work at low frequency also. Present invention is a low
cost easily fabricated high as well as low flow rate micro- machined micropump.
Due to absence of moving parts, the performance of the pump improves and
clogging of micropump has also been eliminated.
BACKGROUND OF THE INVENTION
In the recent years the trends in fluid delivery systems are towards smaller,
more distributed and portable devices for use in biomedical, chemical, aerospace
and many other applications. The origin of microfluidics comes from molecular
analysis, biodefence, molecular biology and microelectronics [1]. To produce large
flow rate, accurate measured results and higher frequency range at micro level

makes this field more challenging [2-4]. With microfluidic technology, it is possible
not only to miniaturize one specific process, but also to combine a multitude of
functionality into one chip level system, called lab-on-chip (LOC) devices, which can
be used in wide research activities [5]. Since the first micropump developed in 1980
for insulin delivery system, many more are developed till now like microfluidic
integrated cells on chip [6] or organs on chip [7], in drug delivery system [8],
cooling system for microelectronics devices [9-13], etc.
In micro electro-mechanical system (MEMS), particularly that of biomedical
field, micro fluid-detection and control components are crucial in utilization related
to the precision automation industry. Among all the micro fluidic system
components, the micro pump is one of the key elements to make a micro fluid
mechanism to work to control fluid in the system. This work demonstrated a novel
design of dielectric elastomer diaphragm for valveless displacement micropump.
Displacement pumps of these types are generally called diaphragm pumps.
Normally two types of displacement pumps are available with check valves and
without check valves. Pumps with check valves are passively controlled by the flow
direction and pressure of the fluid [14]. However, certain disadvantages, like drop
in pressure over the check valves and the risk of wear and fatigue damage to the

moving parts and flow-preventing elements of the valves are present. For
pumping, especially sensitive fluids, primarily liquids, there is also the risk that the
moving valve elements can damage the fluid or negatively affect its properties [15].
To eliminate these limitations for various applications and special fields of
use, there is a pronounced need for valveless micropump. Such pumps contain
nozzle diffuser as a flow control element instead of check valves and the
micropump housing contains a pump chamber with deformable diaphragm driven
by suitable actuator mechanism. Normally used actuation mechanisms are
piezoelectric crystals, thermopneumatic, electrostatic and electromagnetic [13].
U.S. pat. No. 5,836,750 described electrostatically actuated mesopump with
a plurality of elementary cells [16]. The mesopump described therein and other
more primitive pumps all use a plurality of chambers, such as, for example, three or
four chambers, each of which having one diaphragm. While admirably suited for
their intended use, some applications may, in the future, be limited by the size and
compactness of these prior art mesopumps. Also, in some applications for these
mesopumps, the presence of lateral channels and the resulting dead space again

limit their applicability. Present day prior art mesopumps also require moulding of
extra ports to provide pressure relief for unused diaphragm surfaces.
Electrostatically actuated diaphragm pump (US6179586) consists of a single
moulded plastic chamber with two thin diaphragms staked directly on top of each
other [15]. The diaphragms may be actuated with electrostatic, electromagnetic, or
piezoelectric methods.
A piezoelectric driven displacement pump of the diaphragm type (US
6,203,291 B1) having nozzle-diffuser type flow control means has been patented
[17]. Another piezoelectric driven diaphragm type micropump for unidirectional
fluid flow (Indian Patent IN/PCT/2001/00537/DEL) has been patented [18].
Piezoelectric bimorphs are used so that diaphragm could function as both seals and
pump. A magnetically driven micropump [19] for handling small volume of fluid has
been patented (Indian Patent 5821/CHENP/2011). Here the flexible membrane is
being magnetically coupled to an actuator for membrane displacement.
US 8,668,474 B2 shows electroactive diaphragm type valveless pump, in
which an electroactive diaphragm is used [20]. US6408878 B2 shows the micro
fabricated elastomeric valve and pump systems [21].

The major drawbacks of the previously patented micropumps are complex
design, low flow rate, non-bio compatible and high fabrication cost. Present
invention is made to eliminate these limitations and presents a highly cost effective,
simple and efficient micropump to provide large stroke volume and thus high flow
rate. It constitutes a dome shape dielectric elastomer diaphragm [22], pumping
chamber and nozzle/diffuser as flow control element.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose an improved valveless
micropump with dome shaped dielectric elastomer diaphragm, pumping chamber
and nozzle diffuser as flow control element, which is highly cost effective, simple
and efficient to eliminate the disadvantages of prior Arts.
Another object of the invention is to propose an improved valveless
micropump with dome shaped dielectric elastomer diaphragm, pumping chamber
and nozzle diffuser as flow control element which is capable of providing large
stroke volume and thus high flow rate.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1: Shows front view of complete assembly of valveless micropump
according to the invention.
Fig. 2: Shows an isometric view of upper housing of valveless micropump
according to the invention.
Fig. 3: Shows an isometric view of bottom housing of valveless micropump in
accordance with the invention.
Fig. 4: Shows front view of lower housing of pump with dome shape
dielectric elastomer diaphragm.
Fig. 5: Shows Dielectric elastomer actuator diaphragm configuration.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Present invention is a simple, low cost and high performance micropump (1)
developed for delivering fluid at micro range. The top part of the pump is the upper
housing (2) which comprises of a micro nozzle diffuser channel and has a pumping
chamber (7). Bottom part of the micropump is the bottom housing (3) also
comprises of another fluid chamber (8) with drilled hole (9) at the centre to provide

dome shape to the diaphragm (10). Prestretched dielectric elastomer membrane
with compliant electrodes (15) and two passive elastomer membranes (16) have
been used as diaphragm (10) for the reciprocating valveless micropump (1). Both
the upper (2) and the lower part (3) of the micropump (1) have been sealed
through dielectric elastomer double sided adhesive tape and screwed (13, 14)
tightly to prevent any leakage from the micropump. Present invention uses
dielectric elastomer as a diaphragm (10) due to its low cost, flexibility, higher
actuation strain and good shape conformability. Present invention has broad
applications in the field of biomedical, aerospace, automobile, marine engineering,
micromixing, etc.
Present novel valveless diaphragm pump (1) is developed to deliver high
flow rate fluid at micro level. A micro thickness membrane of dielectric elastomer is
used as a diaphragm (10) as well as driver to actuate itself for delivering fluid.
Figure 1, shows the micromachined micropump with its different parts. Upper
housing (2) of the micropump (1) contains fluid pumping chamber (7) with
diaphragm as one of the bounday, nozzle diffuser as a flow directing element and
the reservoirs (11, 12) at the inlet and outlet of the pump. Inlet (5) and outlet (6)
are connected with small diameter tube for intake and delivery of fluid. With this,
diaphragm (10) is attatched with lower part (3) of the micropump (1) with a

prestretched passive elastomer layer (16) above the diaphragm (10) for insulation.
Bottom part of the pump consists of another chamber (8) with a micro drilled hole
(9) which is used for inserting fluid in the chamber (8) to make the diaphragm (10)
a dome shaped. Finally, the two parts are assembled, sealed and screwed (13, 14)
to prevent any type of leakage from the micropump (1).
Due to large deflection of dome shape dielectric elastomer membrane (10)
by applying electric field, a large volume of fluid is sucked into the pump chamber
(7) via the inlet diffuser than via the outlet nozzle during the same suction phase.
During the subsequent displacement phase ("pumping phase") of the pump (1), the
constricting element on the inlet side (5) will, instead, function as a nozzle with
higher flow resistance than the constricting element on the outlet side (6) of the
pump (1) functioning at the same time as the diffuser. This means that a larger
volume of fluid is forced out of the pump chamber (7) via the outlet diffuser than
via the inlet nozzle during the last mentioned displacement or pumping phase. The
result during a complete period (work cycle for the pump) will thus be that a net
large volume has been moved through the pump (1), i.e. pumped, from the inlet
side (5) to the outlet side (6), despite the fact that both constricting elements
permit a fluid flow in both possible flow directions.

The features of the upper housing and the lower housing of the
aforementioned displacement pump are created by micromachining and can be
manufactured at large scale for various application such as fuel injection system in
certain internal combustion engines, insulin dosing, medical and chemical industry
etc.
Figure 2 is illustrating the isometric view of the invention with upper housing
(2) of the micro-machined valveless micropump (1). The housing has a fluid
chamber (7) known as variable pumping chamber. The housing (2) has nozzle
diffuser micro channel (4) of the micro pump (1). Micro channels (4) are flow
directing device of the micropump (1). Figure 2 illustrates in the upper housing inlet
(11) and outlet (12) reservoir for fluid entry and exit respectively with connected
inlet and outlet tube. The embodiment shows the inlet and outlet tube for the fluid
flow in pump. Figure 3 shows the isometric view of lower housing (3) of the
micropump (1) with chamber (8). The housing has a micro drilled hole (9) for
inserting pressurised fluid to make diaphragm (10) a dome. Figure 4 shows the
pump lower housing with dome shape dielectric elastomer diaphragm. Dome shape
of the diaphragm is achieved by injecting pressurised fluid inside the lower
chamber and sealing it. The configuration of the dome shape diaphragm (10) is
shown in Fig. 4.

This is prestretched dielectric elastomer diaphragm (10) sandwiched
between two compliant electrodes (15) as shown in Fig. 5. A conducting tape (17)
is connected with both the electrodes (15) for supplying electric field. The
embodiment shows the prestretched elastomer passive layer (16) for insulating the
electrodes (15) and electrical connections from working fluid.
The dome shape valveless diaphragm micropump (1) with nozzle, diffuser,
pumping chamber (7, 8) is micro-machined precisely. The pump (1) has housing
with a pumping chamber (7) having variable volume driven by dome shape
diaphragm (10) for providing pumping action. The pump chamber (7) comprises
nozzle diffuser type valves for flow control at the inlet and outlet of the pumping
chamber (7). The diaphragm micropump comprising inlet (11) and outlet (12) fluid
reservoir with connected inlet and outlet tube respectively. It has bottom housing
(3) with chamber (8) enclosed with dielectric elastomer diaphragm. This has micro
drilled hole (9) at the chamber for injecting pressurised fluid when the pressurised
fluid make the diaphragm dome shape. The dome shape diaphragm micropump (1)
is a prestretched thin film dielectric elastomer diaphragm (10) sandwiched between
two compliant electrodes (15). The dome shape diaphragm micropump (1)
comprises carbon conducting tape (17) connected with electrodes (15) for high

voltage power source for supplying electric field to the electrodes wherein dome
shape diaphragm (10) has higher stroke length on applying electric field, wherein
the passive elastomer layer (16), acts as an insulating membrane to prevent
electrodes from liquid. The completely assembled dome shape diaphragm
micropump (1) is a leak proof micropump with higher stroke volume and higher
flow rate.

WE CLAIM
1. An improved valveless micropump with dome shaped dielectric elastomer
diaphragm, pumping chamber and nozzle diffuser as flow control element, the said
micropump (1) comprising;
an upper housing comprising a fluid pumping chamber with a diaphragm
(10) as one of the boundary;
a nozzle diffuser (4) for directing flow of fluid;
at least two reservoirs (11, 12) disposed at the inlet (5) and outlet (6) of the
pump (1), the said inlet and outlet connected with small diameter tube for intake
and delivery of fluid;
a bottom housing (3) having a diaphragm (10) attached with lower part of
the micropump with a prestretched passive elastomer layer (16) disposed above
the diaphragm (10);
a fluid chamber (8) disposed in the said bottom housing (3), the said
chamber (8) enclosed with dielectric elastomer diaphragm,
characterized in that,
a micro drilled hole disposed in the fluid chamber (8) for inserting
pressurized fluid in the chamber (8) for making the diaphragm, a dome shaped,

when a carbon conducting tape (17) is connected with both electrodes (15)
for supplying high voltage electric field resulting dome shaped diaphragm having
higher stroke length resulting a large volume of fluid forcing out of the pump
chamber wherein a prestretched elastomer passive layer (16) is disposed in the
diaphragm as an insulating membrane for preventing electrodes from liquid,
wherein, the said two housings (2, 3) are assembled, sealed and screwed for
preventing any leakage from the micropump.
2. An improved valveless micropump as claimed in claim 1, wherein the
prestretched thin film dielectric elastomer diaphragm (10) is sandwiched between
two compliant electrodes (15).
3. An improved valveless micropump as claimed in claim 1, wherein the micro
channels (4) are flow directing device of the micropump (1).
4. An improved valveless micropump as claimed in claim 1, wherein a micro
thickness membrane of dielectric elastomer is used as a diaphragm (10) in the
micropump.