Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Soft Intelligence: Liquids Matter in Compliant Microsystems
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.ORCID iD: 0000-0003-0001-3197
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Soft matter, here, liquids and polymers, have adaptability to a surrounding geometry. They intrinsically have advantageous characteristics from a mechanical perspective, such as flowing and wetting on surrounding surfaces, giving compliant, conformal and deformable behavior. From the behavior of soft matter for heterogeneous surfaces, compliant structures can be engineered as embedded liquid microstructures or patterned liquid microsystems for emerging compliant microsystems.

Recently, skin electronics and soft robotics have been initiated as potential applications that can provide soft interfaces and interactions for a human-machine interface. To meet the design parameters, developing soft material engineering aimed at tuning material properties and smart processing techniques proper to them are to be highly encouraged. As promising candidates, Ga-based liquid alloys and silicone-based elastomers have been widely applied to proof-of-concept compliant structures.

In this thesis, the liquid alloy was employed as a soft and stretchable electrical and thermal conductor (resistor), interconnect and filler in an elastomer structure. Printing-based liquid alloy patterning techniques have been developed with a batch-type, parallel processing scheme. As a simple solution, tape transfer masking was combined with a liquid alloy spraying technique, which provides robust processability. Silicone elastomers could be tunable for multi-functional building blocks by liquid or liquid-like soft solid inclusions. The liquid alloy and a polymer additive were introduced to the silicone elastomer by a simple mixing process. Heterogeneous material microstructures in elastomer networks successfully changed mechanical, thermal and surface properties.

To realize a compliant microsystem, these ideas have in practice been useful in designing and fabricating soft and stretchable systems. Many different designs of the microsystems have been fabricated with the developed techniques and materials, and successfully evaluated under dynamic conditions. The compliant microsystems work as basic components to build up a whole system with soft materials and a processing technology for our emerging society.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. , 93 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1357
Keyword [en]
Liquid, Elastomer, Cross-linking, Liquid alloy, PDMS, Adaptability, Compliance, Interface, Patterning, Printing, Surface energy, Wetting, Composite, Modulus, Stretchability, Viscoelasticity, Thermal conductivity, Contact resistance, Adhesion, Packaging, Integration, Microsystems, Microfluidics, Strain sensor, Thermoelectrics, Inductive coupling, Wireless communication, Stretchable electron-ics, Epidermal electronics, Skin electronics, Soft robotics, Wearable electronics
National Category
Composite Science and Engineering Textile, Rubber and Polymeric Materials Energy Engineering Other Engineering and Technologies not elsewhere specified Embedded Systems Robotics
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Materials Science
Identifiers
URN: urn:nbn:se:uu:diva-281281ISBN: 978-91-554-9521-3 (print)OAI: oai:DiVA.org:uu-281281DiVA: diva2:913616
Public defence
2016-05-11, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2016-04-19 Created: 2016-03-21 Last updated: 2016-04-21
List of papers
1. Liquid alloy printing of microfluidic stretchable electronics
Open this publication in new window or tab >>Liquid alloy printing of microfluidic stretchable electronics
Show others...
2012 (English)In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 22, no 12, 4657-4664 p.Article in journal (Refereed) Published
Abstract [en]

Recently, microfluidic stretchable electronics has attracted great interest from academia since conductive liquids allow for larger cross-sections when stretched and hence low resistance at longer lengths. However, as a serial process it has suffered from low throughput, and a parallel processing technology is needed for more complex systems and production at low costs. In this work, we demonstrate such a technology to implement microfluidic electronics by stencil printing of a liquid alloy onto a semi-cured polydimethylsiloxane (PDMS) substrate, assembly of rigid active components, encapsulation by pouring uncured PDMS on-top and subsequent curing. The printing showed resolution of 200 mm and linear resistance increase of the liquid conductors when elongated up to 60%. No significant change of resistance was shown for a circuit with one LED after 1000 times of cycling between a 0% and an elongation of 60% every 2 s. A radio frequency identity (RFID) tag was demonstrated using the developed technology, showing that good performance could be maintained well into the radio frequency (RF) range.

Place, publisher, year, edition, pages
Royal society of chemistry, 2012
Keyword
liquid alloy, printing, stretchable electronics, wireless communication
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Other Materials Engineering
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-183278 (URN)10.1039/C2LC40628D (DOI)000310865200010 ()
Available from: 2012-10-23 Created: 2012-10-23 Last updated: 2017-12-07Bibliographically approved
2. Adhesive transfer soft lithography: low-cost and flexible rapid prototyping of microfluidic devices, Micro and Nanosystems
Open this publication in new window or tab >>Adhesive transfer soft lithography: low-cost and flexible rapid prototyping of microfluidic devices, Micro and Nanosystems
2014 (English)In: micro and nanosystems, ISSN 1876-4037, Vol. 6, 42-49 p.Article in journal (Refereed) Published
Abstract [en]

A simple and low-cost approach was proposed for prototyping PDMS based microfluidic devices by transferringadhesive film microstructures onto a flexible substrate as a mould for PDMS replicas. The microstructures were engravedon an adhesive coated film using a commercial cutting plotter and then transferred (or laminated) onto a flexiblesubstrate, allowing for engraved isolated patterns. The proposed technique was demonstrated by a hydrodynamic focusingmicrofluidic device, having splitting and re-combining sheath channels. The whole processing could be finished within 1h in a normal laboratory environment. This approach offers an easy, flexible and rapid prototyping of microfluidic andlab-on-a-chip devices to users without expertise in microfabrication. In addition, by minimizing the use of chemicals, theprocess becomes more environmentally friendly than conventional photolithography based micro-fabrication techniques.

Place, publisher, year, edition, pages
Bentham Science Publishers, 2014
Keyword
liquid alloy, printing, soft lithography, rapid prototyping
National Category
Other Engineering and Technologies
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-239241 (URN)
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2016-04-22
3. Tape Transfer Printing of a Liquid Metal Alloy for Stretchable RF Electronics
Open this publication in new window or tab >>Tape Transfer Printing of a Liquid Metal Alloy for Stretchable RF Electronics
2014 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, no 9, 16311-16321 p.Article in journal (Refereed) Published
Abstract [en]

In order to make conductors with large cross sections for low impedance radio frequency (RF) electronics, while still retaining high stretchability, liquid-alloy-based microfluidic stretchable electronics offers stretchable electronic systems the unique opportunity to combine various sensors on our bodies or organs with high-quality wireless communication with the external world (devices/systems), without sacrificing enhanced user comfort. This microfluidic approach, based on printed circuit board technology, allows large area processing of large cross section conductors and robust contacts, which can handle a lot of stretching between the embedded rigid active components and the surrounding system. Although it provides such benefits, further development is needed to realize its potential as a high throughput, cost-effective process technology. In this paper, tape transfer printing is proposed to supply a rapid prototyping batch process at low cost, albeit at a low resolution of 150 mu m. In particular, isolated patterns can be obtained in a simple one-step process. Finally, a stretchable radio frequency identification (RFID) tag is demonstrated. The measured results show the robustness of the hybrid integrated system when the tag is stretched at 50% for 3000 cycles.

Keyword
tape transfer printing, liquid metal alloy, microfluidic stretchable electronics, stretchable RF electronics, radio frequency identification (RFID) tag
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-237588 (URN)10.3390/s140916311 (DOI)000343106600041 ()
Available from: 2014-12-05 Created: 2014-12-03 Last updated: 2017-12-05Bibliographically approved
4. Tape transfer atomization patterning of liquid alloys for microfluidic stretchable wireless power transfer
Open this publication in new window or tab >>Tape transfer atomization patterning of liquid alloys for microfluidic stretchable wireless power transfer
2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, 8419- p.Article in journal (Refereed) Published
Abstract [en]

Stretchable electronics offers unsurpassed mechanical compliance on complex or soft surfaces like the human skin and organs. To fully exploit this great advantage, an autonomous system with a self-powered energy source has been sought for. Here, we present a new technology to pattern liquid alloys on soft substrates, targeting at fabrication of a hybrid-integrated power source in microfluidic stretchable electronics. By atomized spraying of a liquid alloy onto a soft surface with a tape transferred adhesive mask, a universal fabrication process is provided for high quality patterns of liquid conductors in a meter scale. With the developed multilayer fabrication technique, a microfluidic stretchable wireless power transfer device with an integrated LED was demonstrated, which could survive cycling between 0% and 25% strain over 1,000 times.

National Category
Mechanical Engineering
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-247504 (URN)10.1038/srep08419 (DOI)000349245600018 ()25673261 (PubMedID)
Available from: 2015-03-19 Created: 2015-03-19 Last updated: 2017-12-04Bibliographically approved
5. Stretchable wireless power transfer with a liquid alloy coil
Open this publication in new window or tab >>Stretchable wireless power transfer with a liquid alloy coil
2015 (English)In: Micro Electro Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, 2015, 1137-1140 p.Conference paper, Published paper (Refereed)
Abstract [en]

An integrated stretchable wireless power transfer device was demonstrated by packaging rigid electronic chips onto a liquid alloy coil patterned on a half-cured polydimethylsiloxane (PDMS) surface. To obtain low enough resistance, the long liquid alloy coil with a large cross section was made with a tape transfer masking followed by spray deposition of the liquid alloy. The measured results indicated the wireless power transfer efficiency reached 10% at 140 kHz and good performance under 25% overall strain. Different sizes of liquid alloy coils and a soft magnetic composite core were tested to improve the efficiency of the system.

Series
Proceedings IEEE Micro Electro Mechanical Systems, ISSN 1084-6999
Keyword
Liquid alloy, Stretchable electronics, Wireless power transfer, Smart system integration
National Category
Engineering and Technology
Research subject
Materials Science
Identifiers
urn:nbn:se:uu:diva-265529 (URN)10.1109/MEMSYS.2015.7051165 (DOI)000370382900296 ()978-1-4799-7955-4 (ISBN)
Conference
Micro Electro Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, Estoril, January 18-22, 2015
Available from: 2015-10-31 Created: 2015-10-31 Last updated: 2016-04-21Bibliographically approved
6. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment
Open this publication in new window or tab >>Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment
Show others...
2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, 18257Article in journal (Refereed) Published
Abstract [en]

Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

National Category
Textile, Rubber and Polymeric Materials Mechanical Engineering
Identifiers
urn:nbn:se:uu:diva-272055 (URN)10.1038/srep18257 (DOI)000366451800001 ()26671673 (PubMedID)
Funder
Swedish Research Council, 621-2010-5443 621-2014-5596Swedish Foundation for Strategic Research , EM11-0002 SE13-0061
Available from: 2016-01-12 Created: 2016-01-11 Last updated: 2017-11-30Bibliographically approved
7. PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics
Open this publication in new window or tab >>PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics
Show others...
2016 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 28, 5830-5836 p.Article in journal (Refereed) Published
Abstract [en]

Targeting good user experiences, softness and stretchability are essential features for epidermal devices in body signal monitoring and body area stimulation. A highly soft, stretchable and sticky polydimethylsiloxane based elastomer (S3-PDMS) is achieved by a simple process with a widely used siloxane precursors, the properties of which are tuned by adding small fractions of an amine-based polymer, ethoxylated polyethylenimine (EPEI). This allows formation of a thick unobstrusive patch and may ease implementation of epidermal electronics in wearable healthcare applications. 

Keyword
Adhesion, Compliance, Elongation at break, Epidermal electronics, PDMS-based elastomer tuning
National Category
Textile, Rubber and Polymeric Materials Applied Mechanics Polymer Chemistry
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-281212 (URN)10.1002/adma.201505372 (DOI)000382400900004 ()
Funder
Swedish Research Council, 2010-5443
Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2017-11-30Bibliographically approved
8. Stretchable thermoelectric generators metallized with liquid alloy
Open this publication in new window or tab >>Stretchable thermoelectric generators metallized with liquid alloy
Show others...
2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 18, 15791-15797 p.Article in journal (Refereed) Published
Abstract [en]

Conventional thermoelectric generators (TEGs) are normally hard, rigid, and flat. However, most objects have curvy surfaces, which require soft and even stretchable TEGs for maximizing efficiency of thermal energy harvesting. Here, soft and stretchable TEGs using conventional rigid Bi2Te3 pellets metallized with a liquid alloy is reported. The fabrication is implemented by means of a tailored layer-by-layer fabrication process. The STEGs exhibit an output power density of 40.6 mu W/cm(2) at room temperature. The STEGs are operational after being mechanically stretched-and-released more than 1000 times, thanks to the compliant contact between the liquid alloy interconnects and the rigid pellets. The demonstrated interconnect scheme will provide a new route to the development of soft and stretchable energy-harvesting avenues for a variety of emerging electronic applications.

National Category
Energy Engineering Textile, Rubber and Polymeric Materials Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:uu:diva-281213 (URN)10.1021/acsami.7b04752 (DOI)000401307100064 ()28453282 (PubMedID)
Funder
Swedish Foundation for Strategic Research , EM11-0002, SE13-0061Swedish Research Council, 621-2014-5596
Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2017-07-04Bibliographically approved

Open Access in DiVA

fulltext(1947 kB)501 downloads
File information
File name FULLTEXT01.pdfFile size 1947 kBChecksum SHA-512
12a1b4033b1b6b22dc163f24abdfc66a26a33c77c3396dd15a6e616001b33135c31e8f6ad6379934cd03e8ed210fea399af643bd60ab696592af1fbdfdb3830f
Type fulltextMimetype application/pdf
Buy this publication >>

Search in DiVA

By author/editor
Jeong, Seung Hee
By organisation
Microsystems TechnologySolid State Electronics
Composite Science and EngineeringTextile, Rubber and Polymeric MaterialsEnergy EngineeringOther Engineering and Technologies not elsewhere specifiedEmbedded SystemsRobotics

Search outside of DiVA

GoogleGoogle Scholar
Total: 501 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 5260 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf