Directional control on a microfluidic chip
A microfluidic system includes a fluidic platform having a surface, a first liquid disposed onto the fluidic platform, and a droplet disposed onto the first liquid. The first liquid has a first temperature. The droplet has a second temperature higher than the first temperature so that the droplet is levitated above the first liquid by a cushion of vapor of the first liquid. In an embodiment, a device is configured to provide a magnetic field that has variable strength across the surface. A location of a magnetic droplet relative to the surface area is affected by the magnetic field. A method includes providing a fluidic platform, providing a magnetic field, introducing a first liquid onto the fluidic platform, introducing a first magnetic droplet onto the first liquid, and locally varying the magnetic field.
1 . A microfluidic system comprising:
a fluidic platform having a surface;
a first liquid disposed on the fluidic platform, the first liquid having a first temperature;
an array of selectively energizable electrodes configured to provide digital microfluidics, the array of selectively energizable electrodes positioned adjacent to an edge of the fluidic platform, wherein the array of selectively energizable electrodes is configured to move a droplet comprising a second liquid containing magnetic nanoparticles from a location over the array of selectively energizable electrodes to a location over the fluidic platform such that the droplet is disposed over the first liquid; and
an array of selectively energizable electromagnets positioned proximate to the fluidic platform and configured to provide:
an alternating electromagnetic field configured to heat the magnetic nanoparticles in the droplet, thereby causing the droplet to reach a second temperature that is higher than the first temperature such that the droplet is levitated above the first liquid by a cushion of vapor of the first liquid; and
a magnetic field that has variable strength across the surface by selectively energizing different subsets of the array of selectively energizable electromagnets, thereby causing application of a magnetic force to the magnetic nanoparticles in the droplet to move the droplet on the cushion of vapor of the first liquid.
2 . The system of claim 1 wherein the array of selectively energizable electromagnets comprises at least one electromagnet located below the fluidic platform.
3 . The system of claim 1 wherein the array of selectively energizable electromagnets comprises at least one electromagnet located above the fluidic platform.
4 . The system of claim 1 wherein the array of selectively energizable electromagnets comprises a first electromagnet located above the fluidic platform and a second electromagnet located below the fluidic platform.
5 . The system of claim 1 wherein the alternating electromagnetic field is in a radiofrequency range.
6 . The system of claim 1 wherein the fluidic platform is rectangular in shape and wherein the array of selectively energizable electrodes is adjacent to and in contact with at least one side of the rectangular fluidic platform.
7 . The system of claim 1 comprising a first reservoir configured to contain the first liquid before the first liquid is disposed onto the fluidic platform.
8 . The system of claim 7 comprising a second reservoir configured to contain the second liquid before the droplet is disposed over the first liquid.
9 . The system of claim 1 wherein the magnetic nanoparticles comprise at least one of magnetic gold nanoparticles or magnetic iron oxide nanoparticles.
10 . The system of claim 1 wherein the first liquid comprises liquid nitrogen.
11 . A microfluidic system comprising:
a fluidic platform having a surface;
a first liquid disposed onto the fluidic platform, the first liquid having a first temperature;
an array of selectively energizable electrodes, positioned adjacent to an edge of the fluidic platform, configured to provide digital microfluidics to cause movement of a droplet comprising a second liquid containing magnetic nanoparticles from a location over the array of selectively energizable electrodes to a location over the fluidic platform such that the droplet is disposed over the first liquid;
and
an array of selectively energizable electromagnets positioned proximate to the fluidic platform and configured to provide an alternating electromagnetic field in a radiofrequency range to heat the magnetic nanoparticles in the droplet thereby causing the droplet to reach a second temperature that is higher than the first temperature such that the droplet is levitated above the first liquid by a cushion of vapor of the first liquid.
12 . The system of claim 11 wherein the array of selectively energizable electromagnets is further configured to provide a magnetic field that has variable strength across the surface by selectively energizing different subsets of the electromagnets, thereby enabling application of a magnetic force to the magnetic nanoparticles in the droplet to move the droplet on the cushion of vapor of the first liquid.
13 . The system of claim 11 comprising a first reservoir configured to contain the first liquid before the first liquid is disposed onto the fluidic platform.
14 . The system of claim 11 wherein the array of selectively energizable electromagnets comprises at least one electromagnet located below the fluidic platform.
15 . The system of claim 11 wherein the array of selectively energizable electromagnets comprises at least one electromagnet located above the fluidic platform.
16 . A method comprising:
providing a microfluidic system comprising:
a fluidic platform having a surface;
a first liquid disposed onto the fluidic platform, the first liquid having a first temperature;
an array of selectively energizable electrodes configured to provide digital microfluidics, the array of selectively energizable electrodes positioned adjacent to an edge of the fluidic platform, wherein the array of selectively energizable electrodes is configured to move a droplet comprising a second liquid containing magnetic nanoparticles from a location over the-array of selectively energizable electrodes to a location over the fluidic platform such that the droplet is disposed over the first liquid; and
an array of selectively energizable electromagnets positioned proximate to the fluidic platform and configured to provide:
an alternating electromagnetic field configured to heat the magnetic nanoparticles in the droplet, thereby causing the droplet to reach a second temperature that is higher than the first temperature such that the droplet is levitated above the first liquid by a cushion of vapor of the first liquid; and
a magnetic field that has variable strength across the surface by selectively energizing different subsets of the electromagnets, thereby causing application of a magnetic force to the magnetic nanoparticles in the droplet to move the droplet on the cushion of vapor of the first liquid
the method further comprising:
moving, by selectively energizing a subset of the array of the selectively energizable electrodes, a first droplet comprising a second liquid containing first magnetic nanoparticles from a first location over the array of selectively energizable electrodes to a second location over the fluidic platform such that the first droplet is disposed over the first liquid; and
heating the first droplet to a second temperature that is higher than the first temperature, wherein the heating of the first droplet is carried out by an alternating magnetic field provided through the array of selectively energizable electromagnets, such that the first droplet is levitated above the first liquid by a first cushion of vapor of the first liquid.
17 . The method of claim 16 comprising moving the first droplet over the first liquid.
18 . The method of claim 16 comprising injecting the second liquid onto the array of selectively energizable electrodes from a reservoir.
19 . The method of claim 16 wherein introducing the first liquid onto the fluidic platform comprises introducing liquid nitrogen onto the fluidic platform.
20 . The method of claim 16 wherein the alternating magnetic field is in a radiofrequency range.
21 . The method of claim 17 comprising:
moving, by the array of selectively energizable electrodes, a second droplet comprising a third liquid containing second magnetic nanoparticles from a third location over the array of selectively energizable electrodes to a fourth location over the fluidic platform such that the second droplet is disposed over the first liquid;
heating, via the alternating electromagnetic field, the second droplet to a third temperature that is higher than the first temperature, wherein a degree of difference between the first temperature and the third temperature is such that the second droplet is levitated above the first liquid by a second cushion of vapor of the first liquid; and
moving, by the array of selectively energizable electromagnets, the second droplet over the first liquid towards the first droplet.
22 . The method of claim 21 comprising combining the first and second droplets.