Towards molecular computing: Co-development of microfluidic devices and chemical reaction media

Abstract

a b s t r a c tMicrofluidics provides a powerful technology for both the production of molecular computing components and for the implementation of molecular computing architectures. The potential commercial applications of microfluidics drive rapid progress in this field-but at the same time focus interest on materials that are compatible with physiological aqueous conditions. For engineering applications that consider a broader range of physico-chemical conditions the narrow set of established materials for microfluidics can be a challenge. As a consequence of the large surface to volume ratio inherent in microfluidic technology the material of the device can greatly affect the chemistry in the channels of the device. In practice it is necessary to co-develop the chemical medium to be used in the device together with the microfluidic devices. We describe this process for a molecular computing architecture that makes use of excitable lipid-coated droplets of Belousov-Zhabotinsky reaction medium as its active processing components. We identify fluoropolymers with low melting temperature as a suitable substrate for microfluidics to be used in conjunction with Belousov-Zhabotinsky droplets in decane.

Excitability Modulation of Oscillating Media in 3D-Printed Structures

“…An example of a reaction substrate 3D-printed with this material is shown in Figure 1. The elastomer polydimethylsiloxane that is commonly used for microfluidic devices was not used in this study, because it interferes with the BZ reaction cycle [8,16]. The Belousov-Zhabotinsky reaction mixture was prepared by addition of reaction components in the following order: 150 AL of 2.5 M H 2 SO 4 , 405 AL of H 2 O, 750 AL of 1.5 M NaBrO 3 , 870 AL of 1.0 M malonic acid, 150 AL of 1.0 M KBr, and 170 AL of 25 mM ferroin.…”

“…This observation suggests that the volumeto-area ratio, that is, the relative area of the side walls and bottom surface of the channels (solution exposure to the plastic matrix), does not have a prominent effect on BZ excitability. Although the substrate material could influence the BZ reaction by absorption or release of specific molecules [16], it is therefore unlikely that the excitability modulation results to a significant extent from inhibitory interactions with the plastic channel boundaries.…”

Toward Turing’s A-Type Unorganised Machines in an Unconventional Substrate: A Dynamic Representation in Compartmentalised Excitable Chemical Media

“…The vesicles communicate through chemical "signals" as excitation propagates from vesicle to vesicle. Initial experimental implementations which use micro-fluidics to control vesicle placement have recently been reported [25]. This paper begins by considering implementation of the basic two-input NAND gates using the vesicles and then how to design networks of vesicles to perform a given computation.…”

Fabricating millifluidic reaction-diffusion devices: Droplet-in-oil networks structured by laser cutting

“…The active medium can fill channel-connected wells as a continuous phase [5,6], or compartmentalisation can be achieved by self-organisation within the physical structure [7]. An example of the latter scenario is a chain of droplets separated by oil plugs inside a glass capillary of 150 µm diameter [8].…”

“…We have previously described BZ wave propagation in 3D-printed reaction vessels where the channels and the wells contained BZ medium in direct contact with the air [5,13]. The reaction-diffusion medium was physically structured but a two-phase system was not implemented.…”