Abstract
Unconventional computing is an area of research in which novel materials and paradigms are utilised to implement computation. Previously we have demonstrated how registers, logic gates and logic circuits can be implemented, unconventionally, with a biocompatible molecular switch, NitroBIPS, embedded in a polymer matrix. NitroBIPS and related molecules have been shown elsewhere to be capable of modifying many biological processes in a manner that is dependent on its molecular form. Thus, one possible application of this type of unconventional computing is to embed computational processes into biological systems. Here we expand on our earlier proof-of-principle work and demonstrate that universal computation can be implemented using NitroBIPS. We have previously shown that spatially localised computational elements, including registers and logic gates, can be produced. We explain how parallel registers can be implemented, then demonstrate an application of parallel registers in the form of Turing machine tapes, and demonstrate both parallel registers and logic circuits in the form of elementary cellular automata. The Turing machines and elementary cellular automata utilise the same samples and same hardware to implement their registers, logic gates and logic circuits; and both represent examples of universal computing paradigms. This shows that homogenous photochromic computational devices can be dynamically repurposed without invasive reconfiguration. The result represents an important, necessary step towards demonstrating the general feasibility of interfacial computation embedded in biological systems or other unconventional materials and environments.
Highlights
Conventional computing involves the implementation of algorithmic processes to manipulate data on electronic hardware using binary logic
We have previously shown that NitroBIPS can be used to implement registers and logic gates (Chaplin et al, 2012)
This allowed for data to be stored as the relative proportion of fluorescent molecules, and for logic gates and logic circuits to be executed by exploiting the floor and ceiling restrictions of the colourisation and decolourisation processes
Summary
Conventional computing involves the implementation of algorithmic processes to manipulate data on electronic hardware using binary logic. Changing the physical materials used to compute opens up the possibility of embedding computers into biological systems at either a physiological or a cellular level. This could be achieved using biologically compatible molecular switches, for example. Photochromic molecules (Exelby and Grinter, 1965) are a species of molecule with multiple stable forms. They can be reversibly switched between forms via the absorption of electromagnetic radiation. (Berkovic et al, 2000) They possess a colourless leuco spiropyran form (SP) and a coloured trans-merocyanine form (MC). The transition of a sample of spiropyran molecules predominantly occupying the SP state to the MC state is called colouration, and the reverse is called decolouration
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