Dr. Eric Drexler - The Path to Atomically Precise Manufacturing

thank you in for that wonderful

introduction and for the opportunity to

speak to you all this evening and for

the opportunity to be at the Oxford

Martin School and to have an Oxford

Martin School in existence to be at

great thanks

so this afternoon I would like to

outline to the prospects for a turning

point in the development of

nanotechnology the early days of the

concept the focus was on a long term

objective flexible programmable

atomically precise fabrication of

intricate objects including components

for machines that could do a better job

of assembly of intricate atomically

precise structures during that time we

have seen this little maturation of the

development of ways of making molecular

structures that are adequate to get us

to the first rung of the ladder and in

the last few years is that if

technologies has reached a threshold

that will enable us to take a crucial

step and I would like to describe that

step to you today as presentations topic

was first introduced last August and has

been developing some momentum as a

research goal since then so the large

transition ahead is from molecular

self-assembly to molecular active

manufacturing and I'll be talking

hitting several topics here one is where

macroscale fabrication is today the way

we make things in the macroscopic world

by systemic engineering atomically

precise fabrication today which is very

different very contrasting then how to

build on that to develop a first

generation of atomically precise

molecular additive manufacturing systems

than just a few words about early

applications which I will turn over to

Sonia very promptly because she is the

one who is working in the area where the

greatest applications are likely to

emerge the first macroscale fabrication

if you look around you you'll see many

artifacts

see people and we're not artifacts but

virtually everything else you see was

made by machines or with the aid of

machines and those machines were made by

machines or with the aid of machines and

tracing back the genealogy of machines

you'll find earlier and and less

automated and simpler machines if you go

back far enough down the family tree of

industrial technologies you'll find

someone doing this kind of work

shaping materials in a direct way to

make components and tools that could

make better tools more mechanized more

precise that we used to make better and

more complex tools to make better and

more complex products and ultimately a

very intricate technology base making

complex objects has required complex

machinery now we'd like to be able to

make complex objects in the molecular

world to start climbing a ladder of

technologies like the one from

blacksmiths forward but it'd be very

nice to not have to build very complex

systems to make complex objects and in

fact in recent macroscale industrial

progress we've we've seen a way of doing

that you have relatively simple machines

do X Y Z motion of something with

respect to a platform on which one is

building something and to something that

has moved takes some action that results

in a little bit of material being added

sometimes it's using laser to Center a

bit of powdered metal other times it's a

nozzle that's putting down little bits

of melted plastic the most common form

of 3d printer or additive manufacturing

system and the reason this is so

attractive is that rather than having

lathes which cut cylindrically symmetric

objects or various other other

mechanisms for casting with special

tools and and so on where many different

machines are needed to make different

shapes instead additive manufacturing by

adding small amounts of material at a

time with XYZ control bit of material

here a bit more there can make a

tremendous range of shapes including

today aerospace quality materials

that are used this is a component that

Airbus is putting in aircraft that may

fly in and was made by a 3d

manufacturing technology and additive

manufacturing technology well the

essence of such systems again is some

structural framework you know the moving

in XYZ requires a structure to hold

parts together hold a tool with respect

to work piece and stepper motors to

increment on accent increment on winding

for motto NZ to put the the tool where

it needs to be to add the next bit of

material so we have structural framework

stepper motors and then some way of

getting in the typical case materials to

the location and then placing those bits

of material not all 3d printers work

that way and what I will describe and

the molecular world avoids that that bit

of complexity no topically precise

fabrication today back up and ask how do

we make complex things from from

molecules today well the complex

structures that are readily accessible

today using chemistry but also biology

because they're their biomolecules first

and foremost one is DNA which forms

rod-like objects these these guys the

helix the double helixes can be thought

of as a funny kind of twisted rod that

can be used as a structural member the

other class of biopolymers that we can

use to make structural objects and

functional objects or proteins my first

paper in this area and the Proceedings

of the US National Academy of Sciences

was on the prospect of protein

engineering people thought it would be

impossible because it was too complex to

predict how a chain of amino acids would

fold into a 3-dimensional object I've

pointed out that they were trying to

predict how natural proteins will would

fold it's a very different task to

design one that would fold the way you

planned and said aha and that's the root

of the citation tree in this area where

people have gone off and done brilliant

work that is now coming to fruition and

the direction that I had been looking

for as a way of implementing the kind of

system that I'm finally in a position

diplomat after all these years so it's

rather an exciting time

the nice thing about proteins is that

they're highly functional materials they

can be as solid as as would they have

shapes that can be tailored in great

detail they can serve as components for

motors and they can serve as components

for for enzymes that serve as enzymes

that transform other molecules and so on

so DNA is simple soft proteins are a

very good engineering material the great

advantage of DNA is in fact that it's

simple there is a field of technology

known as structural DNA nanotechnology

which can now make hundred nanometers

scale objects on a scale of in terms of

material content millions of atoms and

if you follow design rules making a new

object is about as about as much of a

research project as carpentry there are

ways of holding the Gila C's together in

a systematic way that all is based on

watson-crick base pairing and so these

objects can be designed and made in a

matter of days

proteins have recently reached a

threshold where engineering self

assembling protein objects as of 2014

this report reached through the point of

being able to systematically design

complex objects here we have extended

arrays flat sheets think of those as as

plates that could be used for structural

purposes worked on in 2015 and the way

this works is that you have to

synthesize molecular chains using

chemistry or biology first designing

molecules that will self assemble in

solution they have to have complementary

surfaces DNA that's very simple

watson-crick base pairing proteins it's

a matter of designing pieces that will

fold in a predictable way to make what

amount to 3d puzzle pieces that will

then fit together with other pieces to

make a larger object that's difficult

requires computational search that's

been a long long process to get to the

threshold that was indicated by the

previous two slides

this is very different from macroscale

fabrication you don't put the pieces

where you want them to be you do a very

complex process that enables

self-assembly starting with with

one-dimensional chains so we'd like to

be able to do is additive manufacturing

we put the pieces where you want them to

be and see that would be a fundamentally

different way of manufacturing

atomically precise structures on the

nano scale enable faster more systematic

design wider range of materials be a

technology platform for a fundamentally

new way of making intricate nano scale

objects with atomic precision that is a

very large prospect and now finally

there is a clear picture of how to get

there 3d printers require structural

frameworks and steppers it's still

necessary as for the tip functionality

want to simplify systems now you can

substitute bulk fluid flow and diffusion

to transport materials and instead of

putting pieces where you want them to be

you can take a workpiece and activate a

location so that the building blocks

that are washed and bind there so

three-dimensional designation of where

the blocks go rather than moving the

block much simpler than what people had

thought just a few years ago unlike your

chains are made to do about my chemistry

start with a block attached to a surface

activate a site chemically wash in a

block that reacts there and then

continue by activating at the end

repeating and building a chain and those

are the kinds of chains that will then

fold up to make objects if you're very

clever design such things so the concept

of 3d additive manufacturing with

molecular building blocks is to have a

tool not a chemical on a solution that

washes through wood activates the end of

a chain but a tool that can move around

on a structure and activate a particular

location moving to a particular place

activating the site moving along two

additional ones where you'd like to have

the same next kind of blocked Washington

blocks of that kind and then iterate

additional cycles the different

additional layers different kinds of

blocks on on each cycle to maintain

intricate three-dimensional object this

is a stack of bricks there's no reason

why the object has to be that that

simple in structure so what's required

for that are as they are the machine and

the the building blocks and the tip for

for activating locations if you have

that you can avoid folding chains to

make puzzle pieces have greater design

freedom wider range of parts structures

and functions fast designing fabrication

for product development put the pieces

where you want them to be and a key

point here is that if the structure as

I'll be describing is based on

self-assembly of DNA and proteins for

example in some some auxiliary molecules

made by organic synthesis you don't talk

about how many devices you're making you

talk about how much material is being

self-assemble to make those devices and

in chemistry a milligram is considered

to be respectable but small amount of

material and a gram is considered to be

modest but a very substantial amount of

material machines of this sort would be

on a scale of a hundred nanometers or so

and a milligram of material being

macromolecules assembling to make those

machines provides ten to the twelfth at

a shot one gram 10 to the fifteenth so

rather than having some large machine

that's trying to do precise manipulation

on a surface and spent the pictures of

having a substantial volume fluid

flowing through carrying materials ten

to the twelfth to 10 to the fifteenth

machines working in parallel to to make

things to determine how those building

blocks are arranged that's scalable

quantities and eventually by building

arrays of machines there's a pathway to

scalable product size initial products

would be on the scale of the machines

however which is in 100 nanometers or so

so key components need building blocks

platforms to build on activation tools

those are questions of chemistry there

are many ways of solving those problems

none of them are obvious chemists do

he was very clever in indirect methods

to make structures what's needed here is

clearly within the envelope of what

chemists have done but one we're going

to need a bunch of chemists to actually

figure out what blocks they can

synthesize that meet other system

constraints what the functional groups

are that are activated by what kind of

catalytic mechanism and so on the part

that has been the sticking point the

hard part has been the machine and there

are the two parts again our structural

frameworks and steppers so we need a

system that can move in x y and z x and

y can be performed by strips of

self-assembled structure that are in a

framework something like this is the

axis by by moving the two u-shaped

pieces with respect to one another and

each one of one is carrying the X the X

slider and the other one the Y slider

and that provides the XYZ motion the

reason that this is a boxy configuration

is for a structural rigidity bio bio

polymers are relatively soft relatively

low modulus all else equal lower modulus

means larger thermal fluctuations

thermal fluctuations in a linear elastic

model give a a Gaussian probability

density distribution for the position of

the tip with and thermal fluctuations

are constrained by mechanical forces the

variance is inversely proportional to

the mechanical stiffness and if you have

soft materials you try to build a

structure that is as rigid as possible

with those materials and one that I just

outlined turns out to be a very very

attractive design in that respect and

then the next way of accommodating

thermal fluctuations is you have the

size of the blocks and the targets be

far enough that the probability of

hitting the wrong target is is very low

so numerically those constraints can be

met in a in a in a part of design space

that results in some very attractive

systems the other part which is more

interesting and a release of new ideas

here the structural mechanisms we were

waiting for the fabrication techniques

what's new is a way of making stepper

motors that seems very attractive

probably other ways of doing it but this

one

nice macroscopic world there what are

called three-phase motors stepper motors

in this case we're turning on one set of

windings produces a magnetic field that

produces a potential energy function

that aligns a moving part with respect

to that turning that off while turning

another went on shifts the location that

the moving part wants to sit you turn

that one off turn on another it keeps

shifting you do the you do the three in

reverse order moves the other direction

so each cycle moves a step because

molecular actuators are at a premium

there's a trick where you leave out one

of those steps that have it be kind of

an idle step and that gives three

distinct states which is enough to move

left and right in increments how to do

that well want to have three input

channels for control well a natural way

to do control is by flooding the volume

with light if you can have absorption at

three distinct wavelengths you have

three different addressing channels for

your actuators turns out there's some

dye molecules that absorb very nicely

with well separated Peaks

modest amount of overlap and by putting

in light at three different wavelengths

can activate different sets of molecules

that are activating different phases of

a stepper motor what does that

activation look like well there are

molecules of a family called azo

benzenes which when they absorb a photon

and they flip around a double bond from

a trans configuration on the left to us

this configuration on the right that's

enough to have changed the way they

affect their environment and if that

changes changes the potential by ke T

which is easy that's good enough now

there are two problems when I was first

thinking about this a few years ago one

is that the light these absorb light

only at very short wavelengths the

violet range

you couldn't channel multiple

wavelengths of energy in there because

you can only run the energy downhill the

longer wavelength absorption well in

2013 developed with some clever people

who are trying to get systems

we work in the body we're red light

travels more easily figured out how to

make molecules of this kind that's which

with red light the other problem was

that the reverse switching what took

minutes two hours that time has now been

reduced to the microsecond or nanosecond

range very recent developments 2013 2012

so we have the structures due to recent

advances in protein engineering and

structural DNA nanotechnology we now

have components that are suitable for

motors so those are the key components

the key challenge is coordinated

cross-disciplinary development almost

all of this work in fact actually each

of those technologies has been driven

primarily by an interest in biological

applications biomedical applications

researchers who are developing molecules

for introduction into biology do not

work together to build complex systems

built from those molecules requires a

systems engineering approach where

there's a top-level function we

decompose the function into into

component elements such as framework

versus a motor versus a control system

chemistry for building blocks those need

to be put together and last August there

was a meeting in Berkeley meeting on

integrated nano systems for atomically

precise manufacturing which is exactly

the direction that I've been pointing

for some time person who the this was

held by the advanced manufacturing

office of the US Department of Energy

the program manager is someone who I

first first propagandized when he was a

doctoral student at MIT back in the

1980s so another element that has come

together is an organization that has a

reputation for doing systems engineering

I guess it grew out of the Manhattan

Project in part and they also do

renewable energy and many more more

peaceful developments and they're now

very seriously looking at developing

this placid system there are however

moving at government speed the the

workshop was in August

apparently the final work

draft well they've assembled the

material for a comment by the workshop

participants I'm expecting to see it any

day now and sometime after that there

will be a report from the workshop I can

report that there is also some

preliminary interest around the Oxford

community and in addition we're instead

having a center of coordination for a

systems development effort in this area

in the in the Oxford mill you will see

where that goes very very preliminary

thinking there so early applications

well discussed a lot of them at the at

the workshop for do eight many of them

involving materials processing and

strong materials and filtration

membranes and electro catalytic

membranes for fuel cells energy related

applications but the most attractive

applications I think are in diagnostic

and therapeutic property products in

medicine our bodies are full of

atomically precise structures nanoscale

structures these structures interact

with one another which is how biology

basically works and to be able to make

structures of that kind more rapidly

with more design flexibility more

control and straightforward control of

three-dimensional structure can be very

important to give some sense of the

complexity of structures that people are

investigating today with more

conventional means of assembly here are

some some nanoparticles one class of

applications of nanoparticles with

tailored molecular components for nano

medicine but at this point I would like

to turn the presentation over to a

researcher in nano medicine who can tell

us what kinds of things are being built

today that we could perhaps by providing

better tools unable to move forward even

more rapidly thank you