Universally Programmable
Intelligent Matter
A Systematic Approach to Nanotechnology
Bruce MacLennan
University of Tennessee, Knoxville
Supported by NSF NER grant
and UTK Center for Information Technology Research
Introduction & Definitions
• Intelligent matter: individual molecules or
molecular clusters function as agents
• Universally programmable intelligent
matter: made from a small set of building
blocks that are computationally universal
Goals
• Avoid case-by-case nano-engineering of
materials
• Design one “universal material” that can be
“programmed” for many applications
• Requires a small, fixed set of molecular
building blocks (& reactions), which can be
arranged for varied purposes
• Suggestive evidence for such sets
K-substitution
((K X) Y)  X
K-Substitution
as a Molecular Process
S-Substitution (with Copying)
(((S X) Y) Z)  ((X Z) (Y Z))
S-Substitution (with Sharing)
(((S X) Y) Z)  ((X Z) (Y Z))
Computational Properties
• Universality: S and K can compute
anything that is computable
• Church-Rosser Property: substitutions can
be done in any order without affecting result
SK Computation
• Good model of nondeterministic & parallel
computing
• Has been studied as model of massively
parallel computer architecture
• Functional computer programs can be
compiled into SK networks
Example: Computing a Ring
Ring (X,Y) = R
where rec R = Aux (X,Y,R)
Aux (X, nil, R) = R
Aux (x:X, y:Y, R)
= (x,y) : Aux (X,Y,R)
Example: Computing a Tube
Tube (nil, X, Y)
= Ring (X, Y)
Tube (a:N, X, Y)
= Ring [X, Tube(N,X,Y)]
Extensions
• Sensor operations respond to environmental
conditions
• Effector operations have physical effects on
environment
• Execution of these “imperative” operations
must be controlled
Some Static Applications
• Complex physical structures: chains, tubes,
spheres, fibers, networks, quasi-crystalline
structures
• Membranes with pores or channels
• Very dense analog neural networks
• Sensor & effector organs for microrobots
• Conventional computation
Some Dynamic Applications
• Membrane with controllable channels
• Free-floating clusters controlling fluid properties
• Semiautonomous agents to recognize and bind
molecules
• Sensory transducers, such as artificial retinas &
cochleas
• Effectors, such as cilia & artificial muscle fibers
• Self-repair
Developing an Application
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Write & debug program
Compile into SK network
Simulate on computer
Flatten into DNA sequence
Replicate DNA
Construct molecular network from DNA
Supply reactants for computation
Optionally, replace by permanent groups
Issues
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Appropriate model of computation
Replication/sharing problem
Appropriate choice of combinators
Blocking computation
Nontraditional effects on computation
Dealing with substitution error
Geometrical issues
Supply of reactants
Identifying/synthesizing appropriate reactions
Current Activities
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Developing mathematical model
Theoretical analysis
Developing simulation tool
Programming sample applications