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Publications (10 of 59) Show all publications
An, H., Chen, L., Liu, X., Zhao, B., Ma, D. & Wu, Z. (2018). A method of manufacturing microfluidic contact lenses by using irreversible bonding and thermoforming. Journal of Micromechanics and Microengineering, 28(10), Article ID 105008.
Open this publication in new window or tab >>A method of manufacturing microfluidic contact lenses by using irreversible bonding and thermoforming
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2018 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 28, no 10, article id 105008Article in journal (Refereed) Published
Abstract [en]

In this paper, we present the development of microfluidic contact lenses, which is based on the advantages of wearable microfluidics and can have great potential in the ophthalmology healthcare field. The development consists of two parts; the manufacturing process and the usability tests of the devices. In the manufacturing process, we firstly extended silane coupling and surface modification to irreversibly bond plastic membranes with microchannel-molded silicone rubber, to form the plastic-PDMS plane assemblies, and then molded the plane into a contact lens by thermoforming. We systematically investigated the effects of thermoforming factors, heating temperatures and the terrace die's sphere radius on channels by using the factorial experiment design. In addition, various tests were conducted to verify the usability of the devices. Through blockage and leakage tests, the devices were proved to be feasible, with no channel-blockages and could stand high pressures. Through a wearing test, the contact lenses were confirmed to be harmless on the living body. Furthermore, by performing the manipulating test, the device was proved to be liquid-controllable. These works provide a foundation for the applications of microfluidic contact lenses in ophthalmology.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2018
Keywords
microfluidic contact lenses, thermoforming, factorial experiment, contact lens
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-361480 (URN)10.1088/1361-6439/aaceb7 (DOI)000438633900002 ()
Available from: 2018-09-26 Created: 2018-09-26 Last updated: 2018-09-26Bibliographically approved
Wu, Z., Zhang, S., Vorobyev, A., Gamstedt, E. K., Wu, K., Guo, C. & Jeong, S. H. (2018). Seamless modulus gradient structures for highly resilient, stretchable system integration. MATERIALS TODAY PHYSICS, 4, 28-35
Open this publication in new window or tab >>Seamless modulus gradient structures for highly resilient, stretchable system integration
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2018 (English)In: MATERIALS TODAY PHYSICS, ISSN 2542-5293, Vol. 4, p. 28-35Article in journal (Refereed) Published
Abstract [en]

Hybrid system integration of rigid components into stretchable systems is often necessary when targeting for valuable functions in various scenarios. Among them, (Young's) modulus gradient structures for system integration demonstrate excellent mechanical performance when stretched. However, the mechanical reliability is still limited under large deformation due to the inherent interface between materials of different modulus. Here, a seamless transition between heterogeneous moduli parts made with polydimethylsiloxane (PDMS)-based elastomers is presented for stretchable system integration by simply tuning their modulus via introducing a small amount of an additive into some parts of the substrate. These gradient structures not only provide a high stretchability (similar to 250%) for the overall system, but also improve the resilience of the system (can be stretched up to 50,000 cycles from 0 to 150% global strain) at the same time. The seamless modulus gradient structures provide a simple and effective way of allowing highly resilient and stretchable system integration for various soft intelligent systems.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Seamless modulus gradient structure, Resilience, Stretchability, System integration
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:uu:diva-361000 (URN)10.1016/j.mtphys.2018.02.002 (DOI)000437313500005 ()
Available from: 2018-09-26 Created: 2018-09-26 Last updated: 2018-09-26Bibliographically approved
Cruz, J., Zadeh, S. H., Graells, T., Andersson, M., Malmström, J., Wu, Z. G. & Hjort, K. (2017). High pressure inertial focusing for separating and concentrating bacteria at high throughput. Journal of Micromechanics and Microengineering, 27(8), Article ID 084001.
Open this publication in new window or tab >>High pressure inertial focusing for separating and concentrating bacteria at high throughput
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2017 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 27, no 8, article id 084001Article in journal (Refereed) Published
Abstract [en]

Inertial focusing is a promising microfluidic technology for concentration and separation of particles by size. However, there is a strong correlation of increased pressure with decreased particle size. Theory and experimental results for larger particles were used to scale down the phenomenon and find the conditions that focus 1 mu m particles. High pressure experiments in robust glass chips were used to demonstrate the alignment. We show how the technique works for 1 mu m spherical polystyrene particles and for Escherichia coli, not being harmful for the bacteria at 50 mu l min(-1). The potential to focus bacteria, simplicity of use and high throughput make this technology interesting for healthcare applications, where concentration and purification of a sample may be required as an initial step.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
bacteria separation, particle separation, inertial focusing, high pressure, glass chips, PDMS, microfluidic channel
National Category
Condensed Matter Physics Other Materials Engineering Analytical Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-329919 (URN)10.1088/1361-6439/aa6b14 (DOI)000404540500001 ()
Funder
EU, Horizon 2020, 644669
Available from: 2018-02-22 Created: 2018-02-22 Last updated: 2018-04-23Bibliographically approved
Jeong, S. H., Cruz, J., Chen, S., Gravier, L., Liu, J., Wu, Z., . . . Zhang, Z.-B. (2017). Stretchable thermoelectric generators metallized with liquid alloy. ACS Applied Materials and Interfaces, 9(18), 15791-15797
Open this publication in new window or tab >>Stretchable thermoelectric generators metallized with liquid alloy
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2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 18, p. 15791-15797Article 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
Liu, Z., Xu, W., Hou, Z. & Wu, Z. (2016). A Rapid Prototyping Technique for Microfluidics with High Robustness and Flexibility. Micromachines, 7(11), Article ID 201.
Open this publication in new window or tab >>A Rapid Prototyping Technique for Microfluidics with High Robustness and Flexibility
2016 (English)In: Micromachines, ISSN 2072-666X, E-ISSN 2072-666X, Vol. 7, no 11, article id 201Article in journal (Refereed) Published
Abstract [en]

In microfluidic device prototyping, master fabrication by traditional photolithography is expensive and time-consuming, especially when the design requires being repeatedly modified to achieve a satisfactory performance. By introducing a high-performance/cost-ratio laser to the traditional soft lithography, this paper describes a flexible and rapid prototyping technique for microfluidics. An ultraviolet (UV) laser directly writes on the photoresist without a photomask, which is suitable for master fabrication. By eliminating the constraints of fixed patterns in the traditional photomask when the masters are made, this prototyping technique gives designers/researchers the convenience to revise or modify their designs iteratively. A device fabricated by this method is tested for particle separation and demonstrates good properties. This technique provides a flexible and rapid solution to fabricating microfluidic devices for non-professionals at relatively low cost.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-308592 (URN)10.3390/mi7110201 (DOI)000389131500008 ()
Available from: 2016-11-28 Created: 2016-11-28 Last updated: 2017-11-29Bibliographically approved
Chang, B., Zhou, Q., Wu, Z., Ras, R. & Hjort, K. (2016). Capillary Self-Alignment of Microchips on Soft Substrates. Micromachines, 7(3), Article ID 41.
Open this publication in new window or tab >>Capillary Self-Alignment of Microchips on Soft Substrates
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2016 (English)In: Micromachines, ISSN 2072-666X, E-ISSN 2072-666X, Vol. 7, no 3, article id 41Article in journal (Refereed) Published
Abstract [en]

Soft micro devices and stretchable electronics have attracted great interest for their potential applications in sensory skins and wearable bio-integrated devices. One of the most important steps in building printed circuits is the alignment of assembled micro objects. Previously, the capillary self-alignment of microchips driven by surface tension effects has been shown to be able to achieve high-throughput and high-precision in the integration of micro parts on rigid hydrophilic/superhydrophobic patterned surfaces. In this paper, the self-alignment of microchips on a patterned soft and stretchable substrate, which consists of hydrophilic pads surrounded by a superhydrophobic polydimethylsiloxane (PDMS) background, is demonstrated for the first time. A simple process has been developed for making superhydrophobic soft surface by replicating nanostructures of black silicon onto a PDMS surface. Different kinds of PDMS have been investigated, and the parameters for fabricating superhydrophobic PDMS have been optimized. A self-alignment strategy has been proposed that can result in reliable self-alignment on a soft PDMS substrate. Our results show that capillary self-alignment has great potential for building soft printed circuits.

National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:uu:diva-279824 (URN)10.3390/mi7030041 (DOI)000373053100012 ()
Available from: 2016-03-04 Created: 2016-03-04 Last updated: 2017-11-30Bibliographically approved
Cruz, J., Hooshmand Zadeh, S., Wu, Z. & Hjort, K. (2016). Inertial focusing of microparticles and its limitations. In: : . Paper presented at MME 2016, 27th Micromechanics and Microsystems Europe workshop, August 28-30th 2016, Cork, Irland (pp. 1-6).
Open this publication in new window or tab >>Inertial focusing of microparticles and its limitations
2016 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Microfluidic devices are useful tools for healthcare, biological and chemical analysis and m aterials synthesis amongst fields that can benefit from the unique physics of these systems. In this paper we studied inertial focusing as a tool for hydrodynamic sorting of particles by size. Theory and experimental results are provided as a background for a discussion on how to extend the technology to submicron particles. Different geometries and dimensions of microchannels were designed and simulation data was compared to the experimental results.

Keywords
Particle sorting, Inertial focusing, Micro -fluidic channel, PDMS
National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-309425 (URN)
Conference
MME 2016, 27th Micromechanics and Microsystems Europe workshop, August 28-30th 2016, Cork, Irland
Available from: 2016-12-03 Created: 2016-12-03 Last updated: 2017-01-13Bibliographically approved
Hjort, K. & Wu, Z. (2016). Microfluidic mixing and separation. Journal of Micromechanics and Microengineering, 26(1), Article ID 010402.
Open this publication in new window or tab >>Microfluidic mixing and separation
2016 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 26, no 1, article id 010402Article in journal, Editorial material (Refereed) Published
Keywords
microfluidics, separation, mixing
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-269507 (URN)10.1088/0960-1317/26/1/010402 (DOI)000366868700002 ()
Available from: 2015-12-16 Created: 2015-12-16 Last updated: 2017-12-01Bibliographically approved
Jeong, S. H., Shou, Z., Hjort, K., Hilborn, J. & Wu, Z. (2016). PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics. Advanced Materials, 28(28), 5830-5836
Open this publication in new window or tab >>PDMS-Based Elastomer Tuned Soft, Stretchable, and Sticky for epidermal electronics
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2016 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 28, p. 5830-5836Article 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. 

Keywords
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
Chang, B., Zhou, Q., Ras, R., Shah, A., Wu, Z. & Hjort, K. (2016). Sliding droplets on hydrophilic/superhydrophobic patterned surfaces for liquid deposition. Applied Physics Letters, 108(15), Article ID 154102.
Open this publication in new window or tab >>Sliding droplets on hydrophilic/superhydrophobic patterned surfaces for liquid deposition
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2016 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 108, no 15, article id 154102Article in journal (Refereed) Published
Abstract [en]

A facile gravity-induced sliding droplets method is reported for deposition of nanoliter sized droplets on hydrophilic/superhydrophobic patterned surface. The deposition process is parallel where multiple different liquids can be deposited simultaneously. The process is also high-throughput, having a great potential to be scaled up by increasing the size of the substrate.

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:uu:diva-284240 (URN)10.1063/1.4947008 (DOI)000374314000067 ()
External cooperation:
Available from: 2016-04-15 Created: 2016-04-15 Last updated: 2017-11-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3719-406x

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