Chemical Visualization of Boolean Functions: A Simple Chemical Computer

Abstract

We present a chemical realization of the Boolean functions AND, OR, NAND, and NOR with a neutralization reaction carried out in three coupled continuous flow stirred tank reactors (CSTR). Two of these CSTR's are used as input reactors, the third reactor marks the output. The chemical reaction is the neutralization of hydrochloric acid (HCl) with sodium hydroxide (NaOH) in the presence of phenolphtalein as an indicator, which is red in alkaline solutions and colorless in acidic solutions representing the two binary states 1 and 0, respectively. The time required for a "chemical computation" is determined by the flow rate of reactant solutions into the reactors since the neutralization reaction itself is very fast. While the acid flow to all reactors is equal and constant, the flow rate of NaOH solution controls the states of the input reactors. The connectivities between the input and output reactors determine the flow rate of NaOH solution into the output reactor, according to the chosen Boolean function. Thus the state of the output reactor depends on the states of the input reactors.

Coupled Bistable Chemical Systems - Experimental Realization of Boolean Functions Using a Simple Feedforward Net

“…Recently, these logical functions were carried out chemically by using a neutralization reaction [44].…”

A systems perspective to digital structures in molecular analysis

“…For example, Blittersdorf built Boolean logic gates from a network of three chemical reactors in which the binary state was represented by the level of acidity. 32 In 2002, Adamatzky demonstrated that simple logic gates can be implemented using concentration waves as they constructively or destructively interfere within a given T-shape structure cut from a BZ media gel (Fig. 4d).…”

From chemical soup to computing circuit: transforming a contiguous chemical medium into a logic gate network by modulating its external conditions

“…In order to perform calculations more complex than a single logical operation, it is necessary to connect multiple gates together. In the laboratory, this has often been accomplished via non-chemical means, e. g. * m.egbert@auckland.ac.nz † gagnon01@fas.harvard.edu ‡ jperezmercader@fas.harvard.edu by connecting individual gates together with tubes and pumps [9,11] or via electrical coupling. These approaches require the chemicals comprising each gate to be contained in a vessel, and assume that the chemicals in each vessel are well-stirred.…”

“…In order to perform calculations more complex than a single logical operation, it is necessary to connect multiple gates together. In the laboratory, this has often been accomplished via non-chemical means, e. g. by connecting individual gates together with tubes and pumps [9,11] or via electrical coupling. These approaches require the chemicals comprising each gate to be contained in a vessel, and assume that the chemicals in each vessel are well-stirred.…”