Case 2 - Device Applications of 3D Silicon Microstructures
Submitting Institution
Imperial College LondonUnit of Assessment
Electrical and Electronic Engineering, Metallurgy and MaterialsSummary Impact Type
TechnologicalResearch Subject Area(s)
Physical Sciences: Other Physical Sciences
Chemical Sciences: Physical Chemistry (incl. Structural)
Engineering: Materials Engineering
Summary of the impact
The Optical and Semiconductor Devices group led by Richard Syms has been
a major innovator
in fabrication methods for 3D silicon microstructures, and has developed a
wide range of novel
devices and techniques based on these innovations. T he impact of their
research has been to:
I1) bring the power of mass spectrometry to individual chemists' lab
benches and fume
hoods, raising their effectiveness and productivity through the launch in
2011 of the
world's first commercial desk-top mass spectrometer by Microsaic
Systems plc, a start-up
company founded by members of the group;
I2) create a second start-up company, Nexeon Ltd, to manufacture
nanostructured silicon
anode materials, resulting in reduced battery size and weight for electric
vehicles and
portable electronics;
I3) add to mankind's journey of discovery in space with NASA's Phoenix
Mars Mission in
2008, as part of the Atomic Force Microscope team, helping to investigate
the presence
of liquid water on the surface of Mars.
Underpinning research
The research activity at Imperial College in microsystems (also MEMS —
micro-electro-mechanical
systems), led by Professor Richard Syms, began in 1993. MEMS uses methods
from integrated circuit technology to develop devices with optical,
mechanical, fluidic and other
functions, but is restricted by the largely 2-dimensional nature of IC
processing. From the
beginning, Syms' group focused on developing methods to make 3D
microstructures. Their
first major contribution was the surface tension self-assembly method
(1995) [R1], which
allows batch fabrication of 3D structures — such as optical scanners and
inductors for high
frequency circuits on silicon — by rotating lithographically defined 2D
parts. Other devices
developed by the group included the first microengineered circuit breaker
(2004), and radio
frequency switches (2006).
The group's emphasis on 3D microengineering extended to other techniques
such as
precision optical fibre alignment. In 1995 Syms began a project to
miniaturise quadrupole
mass spectrometers (QMS). The use of silicon alignment structures for the
quadrupole rods,
adapted from the fibre alignment methods, was a breakthrough that allowed
the Imperial team
to develop the world's first microengineered QMS (1996) [R2]. Other
developments drawing
heavily on 3D structuring included a self-aligned electrospray ion gun
(2005) [R3], the basis of
an electrospray mass spectrometer. Research was supported initially by two
EPSRC projects
and later by DTI/LINK in collaboration with the pharmaceutical company
GSK. The latter
project resulted in the realization in microengineered form of three major
building blocks
needed to construct a compact mass spectrometer for life science
applications: a spray
source, a vacuum interface, and a high-performance mass analyser.
Another technique pioneered by the group for 3D structures involves the
use of natural resist,
a method by which thin films "ripen" into sub-micron islands, which then
act as masks for deep
etch processes to form structures such as nanopillars (1999) [R4]. This
work was led by
Emeritus Professor Mino Green. It has the advantage compared to other
sub-micron
patterning techniques that it can be used to process large areas rapidly
and at low cost,
making it suitable for applications where electron-beam writing, for
example, would be
prohibitively expensive. A number of applications enabled by this
technique were developed,
including high surface area substrates for Raman spectroscopy. One
application with
particular commercial impact was opened up when the group demonstrated
that such nano-structured
surfaces could be used in silicon anodes for lithium ion batteries (2003)
[R5]. The
energy density in lithium batteries is limited by the anode's ability to
dissolve lithium, which in
silicon causes damage due to lattice strain. The ability to relax such
strain using a high density
nanopillar array allows significant energy density enhancement at low
production cost.
Professor Tom Pike, who joined the group in 2001, further developed the
field by using 3D
structuring of silicon to create textured substrates for the microscopic
examination of the soil of
Mars. These substrates trapped and separated samples collected by a Mars
surface lander for
detailed imaging by an optical and atomic force microscope (2010) [R6].
The combination of
Pike's space research background and the group's microfabrication
capabilities, including
precision through-wafer etching, provided the basis from which this
innovation arose.
References to the research
(* References that best indicate quality of underpinning research.)
[R1] Green P.W., Syms R.R.A., Yeatman E.M. "Demonstration of
three-dimensional
microstructure self-assembly" IEEE/ASME J. Microelectromech. Syst. 4,
170-176
(1995) DOI: 10.1109/84.475543
[R2] Syms R.R.A, Tate T.J., Ahmad M.M., Taylor S. "Fabrication of
a microengineered
quadrupole electrostatic lens" Elect. Lett. 32, 2094-2095 (1996) DOI: 10.1049/el:19961362
[R3]* Syms R.R.A., Zou H., Bardwell M., Schwab M.-A.
"Microengineered alignment bench for a
nanospray ionisation source" J. Micromech. Microeng. 17, 1567-1574 (2007)
DOI:10.1088/0960-1317/17/8/020
[R4] Green M., Tsuchiya T. "Mesoscopic hemisphere arrays for use
as resist in structure
fabrication" J. Vac. Sci. and Tech. B17, 2074-2083 (1999) DOI: 10.1116/1.590875
[R5]* Green M., Fielder E., Scrosati B., Wachtler M., Serra
Moreno J. "Structured silicon anodes
for lithium battery applications" Electrochem. & Solid-State Letts. 6,
A75-A79 (2003) DOI:
10.1149/1.1563094
[R6]* Goetz, W., Pike, W.T. et al., Microscopy analysis of soils
at the Phoenix landing site,
Mars: Classification of soil particles and description of their optical
and magnetic
properties", J. Geophys. Res. 115, 2156-2202 (2010) DOI: 10.1029/2009JE003437
Details of the impact
We now provide details of the 3 aforementioned impacts and how they are
underpinned by
research in section 2:
I1) Desktop Quadrupole Mass Spectrometer by Microsaic plc
— The novel 3D micro-engineering
methods pioneered by the group [R1], and applications arising from these
[R2], provided the basis for the establishment by Syms, Holmes and Yeatman
of
Microsaic Systems Ltd in 2001. The company obtained a pipeline agreement
to acquire
intellectual property arising from the micro-engineering research of the
founders, and the
unique technologies arising from the group's research provided the basis
for a series of
contracts and awards which funded the growth and development of the
company. In
2006 mass spectrometers were selected as the main business focus, and
Microsaic did
a private equity fundraising of £4M to begin a programme of product
development in this
field. Subsequently, Microsaic developed a set of micro-engineering
innovations [e.g.
E1] that enabled the launch of the world's first commercial compact mass
spectrometer
for liquid analysis, the MiD, in 2011. Microsaic has over 40 granted
patents, of which the
substantial majority are based wholly or in part on research carried out
in the EEE
department by the founders.
Mass spectrometry (MS) is the "gold standard" method for identifying the
constituents in
a sample, and is used in an enormous range of applications including drug
development
and production, forensics, food and drink analysis, security, water
quality and many
others. However, although MS is a $7B market, the size, cost and
complexity of MS
instruments greatly restrict their deployment, so MS is generally provided
in analytical
laboratories, to which users must bring their samples. The Microsaic
system is the size
of a desktop PC, has no external pumps or other peripherals, and thus can
be deployed
much more widely. For example, thousands of chemists work routinely with
chromatographic separation methods such as HPLC (high performance liquid
chromatography) in the development, synthesis, purification and production
of drugs and
other chemicals. Typically they have their own HPLC equipment, but to
definitively
assess their samples they use a central MS facility. Microsaic has made it
practical for
each HPLC station to include mass spectrometry. The MiD also benefits from
much
lower power, gas and solvent consumption than conventional MS instruments.
Quadrupole mass spectrometers work by ionising the molecules in the
sample, and then
"flying" the ions in a vacuum chamber through a mass filter, which uses
electric fields to
separate them by mass-to-charge ratio, directing the selected mass onto a
detector. To
make miniaturisation possible, Microsaic developed three micro-engineered
components: the miniature quadrupole filter itself, an electrospray
ionisation source, and
a vacuum interface chip for bringing ions into the vacuum system. All are
based on
Imperial's research [R2, R3].
Microsaic's 3500 MiD was launched at a major US trade fair, Lab
Automation, where it
won a prestigious New Product Award. In 2012 the 3500 MiD won an R&D
100 award as
one of the major technological innovations of the year. Initial systems
were purchased by
a number of major pharmaceutical companies and university labs in the
first year of the
product's release, and these quickly led to new methods being adopted in
those labs.
For example, Merck & Co Inc, in collaboration with Microsaic and
Imperial College,
published the first demonstration of the use of a miniature MS with HPLC
[E2].
Subsequently, Cambridge University researchers applied Microsaic's compact
MS to
continuous reaction monitoring, and showed that the use of an on-line mass
spectrometer "enabled the flow conditions to be quickly tuned for safe
operation and
optimal generation of the desired product", and "paves the way to
discovering untapped
synthesis methods" [E3].
In May 2012 Microsaic announced a contract with Biotage AB, a major
supplier of flash
chromatography equipment, to supply a minimum of 50 MS instruments per
year,
rebadged as the Isolera Dalton Mass Detector, as part of a combined
MS-flash system.
This system was launched by Biotage in April 2013. The system identifies
compounds by
mass in real time during flash separation, "leading to greater
confidence in purification
and a significant saving in time and money. This combination of
identification and
purification removes complex off-line analytical steps..., vastly
increasing throughput and
putting the entire purification and analysis in the hands of the chemist"
[E4]. Microsaic
was listed on the London Stock Exchange (AIM) in April 2011. It employs
over 35
people, has a market capitalisation of £23.4M (on 21/10/13) and has raised
a further
£11M in equity funding.
I2) Nanostructured silicon anode materials for lithium batteries
— The research group's
other innovation in microstructured silicon that led to a new company was
high capacity
anodes for lithium batteries based on "natural" lithography [R4]. Initial
proof of concept
research by Prof. M Green gave a clear indication that this technology
could provide
substantial enhancement to battery capacity, while being scaleable to
production
volumes at reasonable cost [R5]. As a result the company Nexeon Ltd was
established
in 2006 [E5]. Between 2009 and 2011 Nexeon attracted over £50M in
investment funds,
which it has employed to develop and scale up the technology. It is one of
the "top three
portfolio companies" [E6] of Imperial Innovations plc, which itself has a
market cap. of
£256M (6/10/13). Nexeon has won a number of awards in the Clean Tech
sector,
including the Rushlight Award for Energy Efficiency in 2013 [E7], a
Climate Week Award
in the Best Technological Breakthrough category (2012), and has been named
twice in
the Global Cleantech 100 list (2011 and 2012). It has "signed a
development agreement
with a major consumer electronics and battery OEM" (2012) [E6] and "completed
a
strategic deal with WACKER Chemie AG to provide access to engineering
expertise for
the design and construction of a 250 tonne per annum plant" (2013)
[E6].
I3) NASA's Pheonix Mars Mission — The external impact of the
group's microengineering
research has not only been through commercialisation of its technology.
One example is the
work of Prof. Tom Pike and colleagues on microstructured substrates for
soil analysis [R6],
which led to these substrates being included as part of the atomic force
microscopy
instrument on the 2008 NASA Phoenix mission to Mars [E8,E9]. The mission,
and the
microscopic analysis of the Martian soil, were successful, and added
important evidence in
the ongoing quest to investigate the possibility of life on Mars, by
assessing the exposure of
soil samples to liquid water [E8]. These results generated considerable
public interest and
media coverage [E9] and provided the context for the NASA's subsequent
2012 Mars
Science Laboratory mission [Science articles citing E9]. A
micro-seismometer based on the
group's 3D silicon micromachining technology has also been chosen for
inclusion in the
forthcoming 2016 Insight Mission to Mars, where the Imperial group is the
only team from
the UK included in this multinational project led by NASA [E10].
Sources to corroborate the impact
[E1] US Patent 7,786,434 B2 : Syms R.R.A., Moseley R. "Microengineered
vacuum interface
for an ionisation system" granted on Aug 31, 2010 to Microsaic, describing
an interface
for a miniature mass spectrometer.
[E2] A. Malcolm et al, "A miniature mass spectrometer for liquid
chromatography
applications", Rapid Commun Mass Spectr. 25 (21), 2011, pp 3281—3288. DOI:10.1002/rcm.5230.
[E3] D.L. Browne, "Miniature Mass Spectrometry and On-line Analysis of
Flow Chemistry
Research", The Column 9(6), 2013, pp 2-5.
http://www.chromatographyonline.com/lcgc/Articles/Miniature-Mass-Spectrometry-and-On-line-Analysis-o/ArticleStandard/Article/detail/809098
Archived here
on 23/10/13.
[E4] Biotage AB Web site: http://www.biotage.com/product-page/isolera-dalton
("Read More"
tab). Archived on 23/10/2013 at https://www.imperial.ac.uk/ref/webarchive/y8f.
[E5] Nexeon web site: http://www.nexeon.co.uk/about/history/
Archived on 23/10/1013 at
https://www.imperial.ac.uk/ref/webarchive/7zf
[E6] Imperial Innovations Interim Report HY2013, 22/3/2013 — page 1
http://www.imperialinnovations.co.uk/investor-relations/documents/
Archived here
on
23/10/2013.
[E7] Nexeon Rushlight Award 2009: http://www.rsaaccreditation.org/index.php/rushlight-awards-cs/109-nexeon-clean-energy-award
. Archived on 23/10/2013
https://www.imperial.ac.uk/ref/webarchive/8zf.
[E8] Paper announcing results of the Phoenix mission microscope station:
Pike W. T. Staufer,
U., Hecht M. H., Goetz W., Parrat D., Sykulska-Lawrence H., Vijendran S.,
Madsen M. B.
"Quantification of the dry history of the Martian soil inferred from in
situ microscopy"
Geophys. Res. Lett., 38, L24201 (2011), DOI: 10.1029/2011GL049896.
[E9] Example of press coverage of Imperial's contribution to Phoenix
mission:
http://www.msnbc.msn.com/id/46282840/ns/technology_and_science-space/t/surface-mars-may-be-too-dry-any-alien-life-exist/
Archived on 23/10/2013
https://www.imperial.ac.uk/ref/webarchive/9zf.
[E10] UKSA press release on Imperial's microseismometer's inclusion on
NASA's InSight
mission to Mars: http://www.bis.gov.uk/ukspaceagency/news-and-events/2012/Aug/new-mars-mission-to-take-first-look-at-whats-going-on-deep-inside-the-red-planet.
Archived
on 23/10/2013 at https://www.imperial.ac.uk/ref/webarchive/c1f.