Adventures in the nanoworld
Leigh Canham
University of Birmingham, UK
Friday 9th December 2022 @ University of Nagoya, Japan

Poll 1
https://strawpoll.com/polls/Q0Zp4BwejZM

Which of these statements is NOT true?

Poll 2https://strawpoll.com/polls/bVg86wk73yY

Which of these is NOT a common functionof a porous material?

Layout of talk
• NanoScience/NanoTechnology• Seeing, moving and assembling atoms• Nanoporous materials• Silicon & Nanostructured silicon

https://youtu.be/uIk9ouHrCwM 2022.12.16• Tuning properties with nanomaterials• Fighting cancer & preventing blindness

https://www.pinterest.com/pin/261068109630
060/ 2022.12.19• “Green” synthesis• New types of toothpaste, chewing gum & cosmetics• Careers in (nano) science

https://ja.wikipedia.org/wiki/電子回路 2022.12.16

Definition of nanotechnology
1m

10-1m

10-2m

10-3m

(=1cm)(=1mm)

10-4m

10-5m

10-6m

10-7m

(= 1µm)(=100 nm)

10-8m

10-9m

10-10m(=1nm)

Flea

Hair

Cells

VirusesDNA

Carbon 60(1mm)(80µm)(7µm)(150nm)(2nm)(0.7nm)“Nanotechnology is the design, characterisation, production and application ofstructures, devices and systems by controlling shape and size at nanometre scale”.
The Royal Society Report, July 2004
https://youtu.be/F7vo8hPwQtI 2022.12.16
https://www.lbv.jp/analysis/hairphoto.html

2022.12.16

Seeingnanostructures• Optical microscope

https://www.ibm.com/ibm/history/ibm100/us/en/icons/
microscope/ 2022.12.19• (up to 2000x magnification)• Electron Microscopes• Scanning Tunnelling
Microscopes• Atomic Force Microscopes• (eg. >1,000,000 x)
https://www.pinterest.com/pin/5334655183357253
74/ 2022.12.19

https://www.royce.ac.uk/equipment-andfacilities/atomic-force-microscope-situ-

Manipulating atoms• Published: 05 April 1990
• Positioning single atoms with ascanning tunnelling microscope• D. M. Eigler , E. K. Schweizer• Nature volume 344, pages 524–
526 (1990)

35 Xenon atoms on a cold nickel surface
Took 22 hours (November 9th – 10th 1989) !

Published : 30 April 2013
A boy and his atom : the world’s smallest movie
IBM Research
Youtube 1min. 33 seconds

https://youtu.be/uIk9ouHrCwM 2022.12.16

Types ofnanostructures• Quantum confinement in 1,2 & 3
dimensions• Metals, semiconductors,ceramics, organics• Quantum “dots”, “wires”,“layers”

A 1nm diameter NANOPARTICLE ofsilicon has about 30 atoms• Mesoporous or microporoussolids• Nanoparticles• Nanocolloid• Nanoemulsions• Nanocomposites
A 5nm NANOPARTICLE of silicon
Bayda S, Adeel M, Tuccinardi T, Cordani M, Rizzolio F. The History ofhas more than 3000 atoms

Nanoscience and Nanotechnology: From Chemical-Physical Applications toNanomedicine. Molecules (Basel, Switzerland). 2019 Dec;25(1):E112.

Quiz No 1. Naturally porous !

https://www.facebook.com/timbercut4u/
photos/a.711452155588689/3489027117
831165/ 2022.12.19
https://www.pinterest.jp/pin/432134526
716183802/ 2022.12.20
https://pl.wikipedia.org/wiki/44Pumeks 2022.12.20
https://mobius.world/2021/09/ 2022.12.2
0https://thepotterywheel.com/types-ofclay-for-pottery/ 2022.12.20

Quiz No.2
Well- established synthetic porous materials

https://businessday.ng/news/article/kog
i-dangote-cement-dispute-jubilation-asdangote-cement-obajana-plantreopens/ 2022.12.20
https://ifdesign.com/en/winnerranking/project/spongiosametal/27189 2022.12.20
https://timesofindia.indiatimes.com/lifestyle/health-fitness/health-news/whathappens-if-you-accidentally-eat-a-silicagel-packet-we-tellyou/articleshow/66431539.cms 2022.12.
20https://www.wfbbremen.de/en/page/bremeninvest/mac-panther-materials-metalfoams-from-bremen 2022.12.20

BY PORE SIZE :Classification(IUPAC) ofporous
materials

MACROPOROUS (pore diameter, d, >50nm)
MESOPOROUS ( 2nm > d < 50nm)
MICROPOROUS ( d < 2nm)
BY PORE SHAPE :Cylindical, conical, ink bottle, slit…….
By isotherm position & shape….class I….IV etc

Porosity and nanostructuring• Directional, “honeycomb” porous structure• Nanostructured : mesopores of 2-50nm diameter

1cm3 of mesoporous siliconi.e. sugar cube

Equivalent surface area ofa tennis court

Combined pore length of about
10 million km(25 times distance of earth to moon)• FILTRATION –flow through with restricted access•

SIZE SELECTION• ADSORPTION - selective interaction with skeleton

Commonfunctions ofporous
materials(applications)•CO2 CAPTURE•

TOXIN CAPTURE•SENSING• STORAGE – high surface area/pore volume•

TOXINS, NUTRIENTS, HYDROGEN….

• CONTROLLED RELEASE – restricted diffusion•

DRUGS, VOLATILES, LITHIUM…..

• BARRIER – minimal transport•

THERMAL INSULATION•ELECTRICAL INSULATION• SUPPORT – high surface area for dispersed “actives’•

CATALYSTS•BIOSCAFFOLDSInterfacing silicon with biological building blocks

S Silicon in our environment & society

Electronics

Solar cells

Medical devices
https://www.nasa.gov/vision/earth/features/bm_gallery_5.html 2022.12.21

Communication
EntertainmentTravel
E-Health

EnergyMedical therapyElectronics• >1000 billion $ market• Consumer electronics• Embedded electronics• A decade ago there were already• 6 billion mobile phone contracts• 4 billion people watching television• 640 million PCs

https://businessday.ng/exclusives/article/nigerias-electronics-market-slows-on-weak-purchasing-power/ 2022.12.21

Types of solid silicon
GRADE OFSILICON

INDUSTRYPURITY(%)

COST($/kg)

GLOBALPRODUCTION(tonnes)

Wafer

Electronics

99.99999

1000

5,000Electronic

Si crystals

99.99910-10019,000Solar

Solar cells

99.99

10-5026,000

Chemical

Silicones

99.9

10675,000

Metallurgical

Steel

97-99

1-5

1,000,000

Electronics“from sand”
1.

Sandà Impure silicon

2.

C-Si ingot

3.

Wafers4.

Deposition

5.

Masks

6.

Photolithography

7.

Chips

8.

Protection

9.

Testing
https://www.asm.com/technology/chip-making 2022.12.21

Silica to Metallurgicalgrade Silicon (MG Si)• SiO2 + 2 C à

http://www.microsilicafume.eu/page/silica_fume_microsilica_condense
d_sio2/f1.html 2022.12.21

Si + 2 CO• Submerged Arc furnace with a crucible
diameter about 7 metres and fed by 3 carbonelectrode columns about 15 metres high andweighing 20 tons each• Low cost electricity is critical• Every ton of Silicon needs 12MWh of energy
https://www.sec.gov/Archives/edgar/data/1383571/0001383571
12000009/investorpresentation.htm 2022.12.21

Plummeting
cost ofsiliconbased
electronics

By 2019, nearly 70% of all humans used Si based electronics
https://twitter.com/Bhive_design/status/1502226669155000326 2022.12.21

Photovoltaics

https://project.nikkeibp.co.jp/ms/article/NEWS/20150527/420383/?ST=msb 2022.12.21

https://www.kankyo-business.jp/news/005138.php 2022.12.21

“MEMS” MicroElectroMechanicalSystems• Sandia National Labs, USA
https://www.sandia.gov/media/NewsRel/NR2002/chain.htm 2022.12.21

MEMS Group, Univ. Nagoya, Japan
https://nanofab.engg.nagoya-u.ac.jp 2022.12.21

Tiny devices, often with moving parts, fabricated via similar
techniques & infrastructure developed for microelectronics.

SiliconMEMS
devices

Silicon MEMS Devices

https://cdn-brand.napaonline.com/bosch-automotive/ 2022.12.22

https://youtu.be/qFmeHPVtK0o 2022.12.22
https://www.rfmw.com/products/detail/sit95141aib00030sitime/699874/?pid= 2022.12.22• There are Silicon-based………
…….microrobots, drones……retinas, cochlears, noses, tongues…….timers, pressure sensors……microphones, accelerometers…..

https://www.eetimes.com/memstongue-mimics-tastebuds/ 2022.12.22

https://www.hearingloss.org/hearing-help/technology/cochlearimplantable-devices/ 2022.12.22

Electrochemical etching of solid silicon
Wafer

SOLID
SILICONHF +Anodisationelectric
Galvanic etchingcurrent

Size controlled
microparticles

Stain etching
MACE

HF +oxidant+ metal
catalyst

Very wide size range of directional mesopores in
microparticles and nanoparticles

Motivation for nanostructuring :tunable properties & novel properties
SILICONMESOPOROUS SILICON

Pore Size

N/A

1.5nm

-50nm

Surface Area (BET)

N/A

1-

700 m2/g

Bandgap

1.1eV

1.1-

3.2 eV

Resistivity

10-3 - 103 ohm cm

103-1012 ohm cm

160 GPa

1-

100 GPa

Thermal Conductivity

150 Wm-1 K-1

1-100Wm-1K-1

Refractive Index (IR)

3.5

1.1-

3.0

Youngs Modulus

Tunable opticalproperty :• Refractive index, n• Effective medium
modelling : mixtureof air, silicon, siliconoxide.
• Modulated n• à mirrors• à photonic crystals• à microcavities• à waveguides• à opticalbiosensors

Surf.Sci.Reports 29, 91 (1997)

https://youtu.be/iwj78pR46zM 2022.12.22

Emissive properties :Types of luminescence• PHOTOLUMINESCENCE• ELECTROLUMINESCENCE• CATHODOLUMINESCENCE• CHEMILUMINESCENCE• BIOLUMINESCENCE• MECHANOLUMINESCENCE• LYOLUMINESCENCE• THERMOLUMINESCENCE• RADIOLUMINESCENCE

Quiz No. 3
Type of luminescence ?
https://twitter.com/DrummerBoy2112/status/928618851151106048 2022.12.26

Type of luminescence ?

https://www.amazon.co.jp/TURNMEON-Glow-Sticks-バルクパーティー記念品用品-暗闇で光るパーティーパック
/dp/B0834TMXF2 2022.12.26

Type of luminescence?

Novel property of nanoSi :Visible photoluminescence

Teo et al. Adv.Mater. 18,51 (2006)

Pi Biodegradability
et al. Nanotechn.19,2456031995(2008)
Canham MRS Bulletin 18,22 (1993)

Quiz No.4.
What is a“biomaterial”

Asmatulu, R.. (2023). Biomaterials Course Development for Undergraduate
Engineering Education.

What is a “biomaterial” ?
• “A biomaterial is a nonviable material used in a medical device,intended to interact with biological systems” (Williams 1987)• ‘any substance or combination of substances, other than drugs,
synthetic or natural in origin, which can be used for any periodof time, which augments or replaces partially or totally any
tissue, organ or function of the body, in order to maintain or
improve the quality of life of the individual’’ (NIH, USA)• “a synthetic material used to replace part of a living system orto function in intimate contact with living tissue”( Park & Lakes 1992)• “any material used to make devices to replace a part or functionof the body in a safe, reliable, economic and physiologically
acceptable manner” (Park & Lakes 2007)
à “biomaterial” vs “ biological material”
à “in-vivo” vs “in-vitro” useNovel property of nanoSi :medical biodegradability•

nanostructured silicon undergoes
hydrolysis into orthosilicic acid
Si(OH)4.

•

It can be described as:

Si (s) + 2 H2O (l) à SiO2 (s) + 2 H2 (g)SiO2 (s) + 2 H2O (l) à Si(OH)4 (l)• Silicic Acid is the most natural form ofsilicon - the form we absorb from ourdiet and is present in our blood atabout 1ug/ml• Excretion is via kidneys

Silicon microelectronics in the body
CLINICAL AREA

MICROELECTRONICIMPLANT

Cardiovascular

Pacemaker

Audiology

Cochlear implant

Orthopaedics

Spinal fusion stimulator

Drug delivery

Programmable pump

Urology

Bladder stimulator

Gastroenterology

Endoscopic pill

Neurology

Vagus nerve stimulator

Radiology

In-vivo dosimeter

Obstetrics

Radio pill

Pathology

Smart microneedles

https://seekingalpha.com/article/1604312given-imaging-slightly-undervalued-strongupside-potential-but-also-somerisks 2023.1.4

https://neupsykey.com/v
agus-nerve-stimulationtherapy-2/ 2023.1.4

https://www.ronc.ru/about/lenta-sobytiy/neyrokhirurgionkotsentra-lechat-khronicheskiy-bolevoy-sindrom-spomoshchyu-sovremennykh-implantirue/ 2023.1.4

Biomedical MEMS: Clinical applications of silicon technology.
Technology Tracking Report 201pp .Canham. (IOP Publishing 2003)
http://www.exeterheart.com/services/pacemakers-for-slow-heart-rates-2/ 2023.1.4

Brachytherapy
Drug delivery
Imaging

MEDICAL USES OF
BIODEGRADABLE SILICON

PDT
Orthopaedics

Wound repairTissue engineeringClinical trials & the regulatory
process for a medical device
Device classification

Biocompatibility tests

Phase I Clinical Trial: screening for safety
1.5 years, 10-100 healthy volunteers, $10M

Clinical trials

Phase II: suitable protocol for large study
2 years, 50-500 patients with disease, $20M
Phase III: confirmation of efficacy
3.5 years, 300-30,000 patients, $45M

Marketing approvalClinical Trials - Brachytherapy
First clinical trials:
Liver cancer 2004
Pancreatic cancer 2007

Efficacy:
Tumor regression after
12 wks (CT scan).
Cf. pSiMedica Ltd, UK ; pSiOncology, Singapore

Ocular biomoleculedelivery• Retinal diseases are the main cause ofblindness and severe vision loss inindustrialized contries• Age related Macular Degeneration(AMD)• 34 million people affected in EU currently• Nearly 1 million require treatment• Of particular concern in countries withelderly populations eg. Japan• IVT – monthly injections to back of eye• In UK : Eylea £800 per 2mg injection• Strong driver for sustained release (6month – 1 year) formulations
https://www.technologynetworks.com/neuroscience/news/eye-movement-test-detects-

Application illustration : orthopaedics
4Bone fixators for children’s faces• Biodegradable pins/screws for maxillofacial surgery• Target: moldable osteo-inductive material withslow biodegradability• pSi/PCL molded microcomposite• In-vitro bone marker assays (osteoblasts)• Mechanical characterization

PhD project at Nottingham Medical School.

https://newswitch.jp/image/20116 2023.3.24

2020+

Green synthesis

The semiconductor from plants !
• Botanists call some plants “silicon accumulators”• They take up silicon-based molecules from soil
• They make silica nanostructures in their stems and leaves

https://tabledebates.org/research-library/journal-article-increasedgreenhouse-gas-intensity-rice-production-under-future 2023.1.5

https://www.pinterest.jp/pin/70875406
0082607043/?mt=login 2023.1.5

What are the chemical reactions we can use ?

SiO2 (s) + 2 Mg (g) à Si(s) + 2 MgO (s)3 SiO2 (s) + 4 Al (l) à Si(s) + 2 Al2O3 (s)Vegetation à mesoporous silicon
Silicon accumulator plant
https://www.flickr.com/phot
os/30541846@N03/7837951
872 2023.1.5

1.Cultivate, crop ,wash, dry, grind
2.HCl-based wash
3.Calcination
https://akbelkimya.com.tr/sodyummetasilikat-143-urun 2023.1.5

Biogenic silica plant extract
1.Magnesiothermic reduction
2.HCl wash to remove Mg phases

Biogenic mesoporous silicon
https://www.belt-furnace.com/projects 2023.1.5

Continuous feeding of trays
with powders of biogenic
silica, magnesium and salt
(30g batch size)

Batchelor et al. Silicon 4: 259-266 (2012)

2010-2015

Intrinsiq
Nanomaterials Ltd
Nutrition, cosmetics andconsumer care products from
nanoporous silicon
Functional foods
Chewing gum
Sunscreens
Toothpaste

https://m.facebook.com/zerocater/photos/a.464370606909628/23003845899
74878/?type=3&source=54 2023.1.11

Quiz No. 5
What is it in toothpaste that cleans our teeth?

Market sector

Global Market(billion $)Oral hygiene

24

toothpaste

14

toothbrushes

6

mouthwash

2

denture care

1.7

dental floss

0.5

Answer :Abrasives

Crushed bone…….crushed egg shells …. Powdered charcoal
Alumina……….calcium phosphate…………..calcium carbonate
Silica…à porous silica à porous silicon?
Strength vs Hardness
Cleaning vs Eroding
Our target : multifunctional gentle toothpaste

https://www.facebook.com/Coipiodonto/photos/4638782186198182 2023.1.11

Functional foods

Nutrient protection
Nutrient bioavailability
Controlled release

https://youtu.be/MWYDOPtw6Fc 2023.1.11• Stability in saliva,
stomach fluid,intestinal fluid.
• Taste & mouthfeel• Oral toxicity• Colour• GRAS status• pSiMedica Ltd• Intrinsiq Materials Ltd

12wt% silicon

10wt% silica

10wt% silicon

How can we improve Chewing Gum ?

http://napajapan-candy.blogspot.com/2016/11/japanesechewing-gum-options-galore.html 2023.1.11

Application illustration: foodstuff• Target : multifunctional gum• £18 billion global market ……..>20% of population in
Japan chew gum once a week (2017 survey)
••
•

•

•

Controlled release of actives through modulation of particle porosity
Improved bioavailability or dissolution kinetics through entrapment inmesopores
Improved range of actives:• flavours , sweeteners & nutrients• antimicrobials• effect ingredients
Re-mineralization – possibility of using it as a re-mineralizing agent insitu for sensitive teeth

Stride gum – flavour switchinghttps://bigdaddysliquors.com/shop?productid=57aa2a1269702d1fad1b0e01&optionid=4ccb2db22e09ca5cce45d637edaf04eafb3b0d954e
d597ba5073c52e398f5885 2023.1.11

http://www.nearof.com/review-stride-spark-vitaminchewing-gum/ 2023.1.12

Application example : cosmetics• OPPORTUNITIES :• Eg. Anti-aging formulations : optical brighteners (facial)• à biocompatible blue/green emitting silicon nanoparticles• Eg. Sunscreen in bronzers• à UV absorbing brown microparticle¥s• Eg. Sebum absorbent in foundation• à High pore volume microparticlesBronzers

Foundation

https://phpspot.org/blog/archives/2008/07/photoshop_83.html 2023.1.12

Facial creamOpportunities: Academic research, industrial research, industrial
product development, technology analysts, technology marketing,freelance consultant, entrepreneurship, teaching, patent attorney,scientific publishing, scientific journalism, TV presenter………………

What area(s) of science do I enjoy most?

Careers inscience

Am I more interested in understanding or using science?

Am I more practical or more analytical?

Is job satisfaction or salary more important to me?

Are you creative or innovative or afuture entrepreneur?
• Akio Morita• Tsunezawa Kahoko• Albert Einstein

https://www.britannica.com/biography/St
eve-Jobs 2023.1.12• Elvis Presley• Steve Jobs
• Florence Nightingale

https://musique2013.hatenablog.com/entry/2015/02/09/154355 2023.1.12

SORAIA GUERREIRO(2016), Intelligent minds, SFGUERREIRO.

https://aptwomen.tokyo/program/partici
pant/participant12.html 2023.
1.12
https://www.wikiwand.com/ja/盛田昭夫 2023.1.12

Careers in nanoscience & nanotechnology
Interdisciplinary :Physics,chemistry,biology,medicine,engineering….

Making nanocrystals,nanowires, superlattices

Theoretical understanding

Making, marketing, selling
nano-products

Teaching & research innanoscience

Explaining to the generalpublicWorking with viruses, cells,animals, human patientshttps://www.cbc.ca/news/world/tokyomedical-university-women-admissiondiscrimination-altering-exam1.4779570 2023.1.12

Concluding comments• We now have the tools to study the nanoworld in
detail• Exploring & manipulating materials at the nanoscale
reveals novel properties and can give size-tunableproperties• Nanoporous silicon has found varied uses outside
electronics and photovoltaics• Nanoscience and nanotechnology are very
interdisciplinary and offer a range of career options

https://www.hitachi-

https://www.wsj.com/articles/BL-JRTB20053 2023.1.12

Poll 1
https://strawpoll.com/polls/Q0Zp4BwejZM

Which of these statements is NOT true?

Poll 2https://strawpoll.com/polls/bVg86wk73yY

Which of these is NOT a common functionof a porous material?