Microfluidic manipulation of droplets using synchronous universal logic operations

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From Zuse's thesis, which pioneered digital physics, to Landauer and Wheeler's famous `it from bit', we know that information is fundamentally linked to its physical representations; manipulation of information, for example, represented by the flow of electrons in a microcircuit or biological molecules, intrinsically leads to algorithmic manipulation of matter. Although such algorithmic assembly is commonplace nowadays at the nanoscale, including DNA- based tile nanostructures, its counterpart at the mesoscale is surprisingly missing. Droplets in microfluidic chambers are a growing platform for both physics and biology experiments. Droplets are indeed versatile digital materials; they can be produced in large quantities at high throughput, perform chemical reactions as miniature beakers and carry biological entities. Several manipulation techniques, including electric, optical, acoustic and magnetic forces, have been used for serially manipulating droplets. Because these systems depend on external feedback by the user and lack any inherent computational capability, large scale-up and parallel information-based manipulation is limited. A simple assignment of presence or absence of a droplet as a bit of information can allow us to look at these multi-phase systems as information processing units. Recent work has demonstrated the universal computational capabilities of low-Reynolds-number multi-phase hydrodynamics using pressure-based flow controllers . However, all of these prior systems suffer from a fundamental drawback; they are asynchronous and thus lack the capacity to scale to complex cascaded digital logic. To address this problem, I introduce a new platform that uses a single global clock, that is, a rotating magnetic field to synchronize the motion of arbitrary numbers of droplets and direct or store them in permalloy tracks using digital logic operations. The manipulation of the droplets is magnetophoretic; the rotating magnetic field activates the permalloy tracks to create a dynamic energy landscape that sets the droplets in motion. I demonstrate that the droplets in my platform can either be paramagnetic, that is ferrofluidic, or diamagnetic, for water that is essentially diamagnetic - in practice non-magnetic. Through magnetic and hydrodynamic interaction forces between droplets, we developed OR/AND logic gates, universal XOR/AND and XOR/NAND gates, fanouts, memory loops, flip-flops, a finite-state machine and a full adder that adds droplet `bits'. Our platform demonstrates both combinational and sequential logic and does not rely on pressure-based flow controllers, therefore enabling a unique `non-volatile' conservative physical logic and memory. Our platform enables large-scale integration of droplet logic, analogous to the scaling seen in digital electronics, and opens new avenues in mesoscale material processing.


Type of resource text
Form electronic; electronic resource; remote
Extent 1 online resource.
Publication date 2016
Issuance monographic
Language English


Associated with Katsikis, Georgios
Associated with Stanford University, Department of Mechanical Engineering.
Primary advisor Prakash, Manu
Primary advisor Santiago, Juan G
Thesis advisor Prakash, Manu
Thesis advisor Santiago, Juan G
Thesis advisor Pease, R. (R. Fabian W.)
Advisor Pease, R. (R. Fabian W.)


Genre Theses

Bibliographic information

Statement of responsibility Georgios Katsikis.
Note Submitted to the Department of Mechanical Engineering.
Thesis Thesis (Ph.D.)--Stanford University, 2016.
Location electronic resource

Access conditions

© 2016 by Georgios Katsikis
This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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