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  • 1.
    Ahlberg, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Seung, Hee Jeong
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jiao, Mingzhi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Graphene as a Diffusion Barrier in Galinstan-Solid Metal Contacts2014In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 61, no 8, p. 2996-3000Article in journal (Refereed)
    Abstract [en]

    This paper presents the use of graphene as a diffusion barrier to a eutectic Ga-In-Sn alloy, i.e., galinstan, for electrical contacts in electronics. Galinstan is known to be incompatible with many conventional metals used for electrical contacts. When galinstan is in direct contact with Al thin films, Al is readily dissolved leading to the formation of Al oxides present on the surface of the galinstan droplets. This reaction is monitored ex situ using several material analysis methods as well as in situ using a simple circuit to follow the time-dependent resistance variation. In the presence of a multilayer graphene diffusion barrier, the Al-galinstan reaction is effectively prevented for galinstan deposited by means of drop casting. When deposited by spray coating, the high-impact momentum of the galinstan droplets causes damage to the multilayer graphene and the Al-galinstan reaction is observed at some defective spots. Nonetheless, the graphene barrier is likely to block the formation of Al oxides at the Al/galinstan interface leading to a stable electrical current in the test circuit.

  • 2.
    An, Hongbin
    et al.
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    Chen, Liangzhou
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    Liu, Xiaojun
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    Zhao, Bin
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    Ma, Donglin
    Huazhong Univ Sci & Technol, Sch Opt & Elect Informat, Wuhan 430074, Hubei, Peoples R China.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Hubei, Peoples R China.
    A method of manufacturing microfluidic contact lenses by using irreversible bonding and thermoforming2018In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 28, no 10, article id 105008Article in journal (Refereed)
    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.

  • 3.
    An, Hongbin
    et al.
    HUST, Sch Mech Sci & Engn, Wuhan 430074, Hubei, Peoples R China.
    Chen, Liangzhou
    HUST, Sch Mech Sci & Engn, Wuhan 430074, Hubei, Peoples R China.
    Liu, Xiaojun
    HUST, Sch Mech Sci & Engn, Wuhan 430074, Hubei, Peoples R China.
    Zhao, Bin
    HUST, Sch Mech Sci & Engn, Wuhan 430074, Hubei, Peoples R China.
    Zhang, Hong
    HUST, Tongji Med Coll, Tongji Hosp, Dept Ophthalmol, Wuhan 430074, Hubei, Peoples R China.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. HUST, Sch Mech Sci & Engn, Wuhan 430074, Hubei, Peoples R China.
    Microfluidic contact lenses for unpowered, continuous and non-invasive intraocular pressure monitoring2019In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 295, p. 177-187Article in journal (Refereed)
    Abstract [en]

    Intraocular pressure (IOP) is a crucial physiological indicator of the visual system and play a key role in the diagnosis and treatment of glaucoma. However, the current handheld single measurement tools for IOP sensing cannot meet the future demands for glaucoma management. Thus, here we present the microfluidic contact lens sensors that could provide unpowered, continuous and non-invasive IOP monitoring. The microfluidic contact lens is comprised of a sensing layer of the micropatterned soft-elastomer and a hard plastic reference layer. The devices use the annular sensing chamber filled with the dyed liquid and a sensing microchannel as the IOP transducer. Resulting from the volume variance of the sensing chamber and caused by the deformation of the sensing layer under pressure, the IOP signal is detected as the displacement change of the dyed liquid's interface in the sensing channel, and in which, the displacement change can be optically observed by using the smart-phone camera. Based on the silicone rubber model eyeball, the sensing mechanism of the devices with different design parameters (the position of the sensing chambers and the dimension of the sensing channels) are explored by using the theoretical analyses and experimental investigations. The characteristics of these microfluidic contact lens sensors are tested, in which, the maximum sensitivity of the device (with the sensing chamber of 8.5 mm in diameter and the sensing channel of 100 x 40 um in size) can be achieved to 0.708 mm/mmHg in a working range of 0 (4) over tilde0 mmHg. Also, cyclical tests were conducted and indicated that the devices had a good reversibility and Long-term stability. Furthermore, the device (with the sensing chamber of 5.0 mm in diameter and the sensing channel of 150 x 40 urn in size) was test on the porcine eyes ex vivo, showing a sensitivity of 0.2832 mm/mmHg in a range of 8 (3) over tilde2 mmHg and, the device had a good reproducibility to its IOP change. This work provides a promising approach for unpowered, continuous and non-invasive monitoring of IOP.

  • 4.
    Chang, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zhou, Quan
    Aalto University, Finland.
    Ras, Robin
    Aalto University, Finland.
    Shah, Ali
    Aalto University, Finland.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Sliding droplets on hydrophilic/superhydrophobic patterned surfaces for liquid deposition2016In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 108, no 15, article id 154102Article in journal (Refereed)
    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.

  • 5.
    Chang, Bo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Aalto Univ, Sch Sci, Dept Appl Phys, FI-00076 Aalto, Finland.
    Zhou, Quan
    Aalto Univ, Dept Elect Engn & Automat, FI-00076 Aalto, Finland.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
    Ras, Robin
    Aalto Univ, Sch Sci, Dept Appl Phys, FI-00076 Aalto, Finland.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Capillary Self-Alignment of Microchips on Soft Substrates2016In: Micromachines, ISSN 2072-666X, E-ISSN 2072-666X, Vol. 7, no 3, article id 41Article in journal (Refereed)
    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.

  • 6.
    Cheng, Shi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Liquid metal stretchable unbalanced loop antenna2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 94, no 14, p. 144103-Article in journal (Refereed)
    Abstract [en]

    We present a 2.4 GHz unbalanced loop antenna that can be stretched along multiple dimensions simultaneously. It was realized by incorporating room temperature liquid metal alloy into microstructured channels in an elastic material. The demonstrated prototype exhibits a stretchability of up to 40% along two orthogonal orientations as well as foldability and twistability. Port impedance and radiation characteristics of the nonstretched and stretched antenna were studied numerically and experimentally. Measured results indicate a radiation efficiency of more than 80%.

  • 7.
    Cheng, Shi
    et al.
    Advanced Technology, Laird Technologies, Kista.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    A Microfluidic, Reversibly Stretchable, Large-Area Wireless Strain Sensor2011In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 21, no 12, p. 2282-2290Article in journal (Refereed)
    Abstract [en]

    This article describes the implementation and characterization of a new self-contained large-area wireless strain sensor, operating around 1.5 GHz, based on the concept of multi-layer microfluidic stretchable radiofrequency electronics (mu FSRFEs). Compared to existing solutions, the presented integrated strain sensor is capable of remotely detecting repeated high tensile dynamic strains of up to 15% over very large surfaces or movable parts, and gets rid of all hardwiring to external storage or data processing equipment. Unlike conventional electronic devices, the major part of the sensor is a mechanically reconfigurable and reversibly deformable patch antenna, which consists of two layers of liquid metal alloy filled microfluidic channels in a silicone elastomer. A simplified radiofrequency (RF) transmitter composed of miniaturized rigid active integrated circuits (ICs) associated with discrete passive components was assembled on a flexible printed circuit board (FPCB) and then heterogeneously integrated to the antenna. The elastic patch antenna can withstand repeated mechanical stretches while still maintaining its electrical function to some extent, and return to its original state after removal of the stress. Additionally, its electrical characteristics at frequency of operation are highly sensitive to mechanical strains. Consequently, not only is this antenna a radiator for transmitting and receiving RF signals like any other conventional antennas, but also acts as a reversible large-area strain sensor in the integrated device. Good electrical performance of the standalone antenna and the RF transmitter sub-module was respectively verified by experiments. Furthermore, a personal computer (PC)-assisted RF receiver for receiving and processing the measured data was also designed, implemented, and evaluated. In the real-life demonstration, the integrated strain sensor successfully monitored periodically repeated human body motion, and wirelessly transmitted the measured data to the custom-designed receiver at a distance of 5m in real-time.

  • 8.
    Cheng, Shi
    et al.
    Radio Hardware Division at Ericsson.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Microfluidic electronics2012In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 12, no 16, p. 2782-2791Article in journal (Refereed)
    Abstract [en]

    Microfluidics, a field that has been well-established for several decades, has seen extensive applications in the areas of biology, chemistry, and medicine. However, it might be very hard to imagine how such soft microfluidic devices would be used in other areas, such as electronics, in which stiff, solid metals, insulators, and semiconductors have previously dominated. Very recently, things have radically changed. Taking advantage of native properties of microfluidics, advances in microfluidics-based electronics have shown great potential in numerous new appealing applications, e. g. bio-inspired devices, body-worn healthcare and medical sensing systems, and ergonomic units, in which conventional rigid, bulky electronics are facing insurmountable obstacles to fulfil the demand on comfortable user experience. Not only would the birth of microfluidic electronics contribute to both the microfluidics and electronics fields, but it may also shape the future of our daily life. Nevertheless, microfluidic electronics are still at a very early stage, and significant efforts in research and development are needed to advance this emerging field. The intention of this article is to review recent research outcomes in the field of microfluidic electronics, and address current technical challenges and issues. The outlook of future development in microfluidic electronic devices and systems, as well as new fabrication techniques, is also discussed. Moreover, the authors would like to inspire both the microfluidics and electronics communities to further exploit this newly-established field.

  • 9.
    Cheng, Shi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Microfluidic Reversibly Stretchable Large-Area Wireless Strain Sensor2011In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 21, no 12, p. 2282-2290Article in journal (Refereed)
  • 10.
    Cheng, Shi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Microfluidic stretchable RF electronics2010In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 10, no 23, p. 3227-3234Article in journal (Refereed)
    Abstract [en]

    Stretchable electronics is a revolutionary technology that will potentially create a world of radically different electronic devices and systems that open up an entirely new spectrum of possibilities. This article proposes a microfluidic based solution for stretchable radio frequency (RF) electronics, using hybrid integration of active circuits assembled on flex foils and liquid alloy passive structures embedded in elastic substrates, e. g. polydimethylsiloxane (PDMS). This concept was employed to implement a 900 MHz stretchable RF radiation sensor, consisting of a large area elastic antenna and a cluster of conventional rigid components for RF power detection. The integrated radiation sensor except the power supply was fully embedded in a thin elastomeric substrate. Good electrical performance of the standalone stretchable antenna as well as the RF power detection sub-module was verified by experiments. The sensor successfully detected the RF radiation over 5 m distance in the system demonstration. Experiments on two-dimensional (2D) stretching up to 15%, folding and twisting of the demonstrated sensor were also carried out. Despite the integrated device was severely deformed, no failure in RF radiation sensing was observed in the tests. This technique illuminates a promising route of realizing stretchable and foldable large area integrated RF electronics that are of great interest to a variety of applications like wearable computing, health monitoring, medical diagnostics, and curvilinear electronics.

  • 11.
    Cheng, Shi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hallbjörner, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology.
    Foldable and stretchable liquid metal planar inverted cone antenna2009In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 57, no 12, p. 3765-3771Article in journal (Refereed)
    Abstract [en]

    A mechanically flexible planar inverted cone antenna (PICA) for   ultrawideband (UWB) applications is presented. It can be both folded   and stretched significantly without permanent damage or loss of   electrical functionality. The antenna is manufactured with a process in   which conductors are realized by injecting room temperature liquid   metal alloy into micro-structured channels in an elastic dielectric   material. The elastic dielectric material together with the liquid   metal enables bending with a very small radius, twisting, and   stretching along any direction. Port impedance and radiation   characteristics of the non-stretched and stretched antenna are studied   in simulations and experiments. The presented antenna has a return loss   better than 10 dB within 3-11 GHz and a radiation efficiency of > 70%   over 3-10 GHz, also when stretched. Tests verify that stretching up to   40% is possible with maintained electrical performance. The presented   antenna is useful for example for body-worn antennas and in   applications in harsh environments where mechanical flexibility helps   improve durability.

  • 12.
    Cheng, Shi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    A highly stretchable microfluidic meandered monopole antenna2009In: 13th International Conference on Miniaturized Systems for Chemistry and Life Sciences µTAS 2009, 2009, p. 1946-1948Conference paper (Refereed)
  • 13.
    Cruz, Javier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hooshmand Zadeh, S
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, China.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Inertial focusing of microparticles and its limitations2016Conference paper (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.

  • 14.
    Cruz, Javier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zadeh, S. Hooshmand
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Graells, Tiscar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. Univ Autonoma Barcelona, Dept Genet & Microbiol, Barcelona, Spain..
    Andersson, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Malmström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Wu, Zhigang G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan, Peoples R China..
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    High pressure inertial focusing for separating and concentrating bacteria at high throughput2017In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 27, no 8, article id 084001Article in journal (Refereed)
    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.

  • 15.
    Cruz, Javier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zadeh, S. Hooshmand
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Wu, Zhigang G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan, Hubei, Peoples R China.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Inertial focusing of microparticles and its limitations2016In: 27Th Micromechanics And Microsystems Europe Workshop (Mme 2016), 2016, article id 012028Conference paper (Refereed)
    Abstract [en]

    Microfluidic devices are useful tools for healthcare, biological and chemical analysis and materials 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.

  • 16.
    Deng, Pan
    et al.
    Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan, Hubei, Peoples R China.
    Fu, Cheng-Jie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan, Hubei, Peoples R China.
    High purity and viability cell separation of a bacterivorous jakobid flagellate based on a steep velocity gradient induced soft inertial force2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 62, p. 35512-35520Article in journal (Refereed)
    Abstract [en]

    Cell separation is one of the key limiting factors for precise analysis of non-axenic microbial lab cultures or environmental samples, and it remains a challenge to isolate target cells with high purity and viability via high-throughput cell sorting. During the past decade, hydrodynamic microfluidic platforms have attracted great attention in cell preparation for their high efficiency, robust performance and low cost. Here, we employ the use of a low-velocity sheath flow with high viscosity near the wall and a high-velocity sheath flow with low viscosity on the other side of the sample flow in a soft inertial separation chip. This not only prevents hard interactions between cells and chip walls but, in comparison to previous inertial separation methods, generates a significant increase in deflection of large cells while keeping the small ones in the original flow. We first conducted experiments on a mixture of small and large fluorescent particles (1.0 and 9.9 m, respectively) and removed over 99% of the small particles. The separation efficiency was then tested on a culture of a bacterivorous jakobid flagellate, Seculamonas ecuadoriensis fed on the live bacterium, Klebsiella sp. Using our microfluidic chip, over 94% of live bacteria were removed while maintaining high jakobid cell viability. For comparison, we also conducted size-based cell sorting of the same culture using flow cytometry, which is widely used as a rapid and automated separation tool. Compared with the latter, our chip showed more than 40% higher separation efficiency. Thus, our device provides high purity and viability for cell separation of a sensitive cell sample (jakobid cells). Potentially, the method can be further used for applications in diagnostics, biological analyses and environmental assessment of mixed microbial samples.

  • 17.
    Hjort, Klas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Huazhong University of Science and Technology.
    Microfluidic mixing and separation2016In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 26, no 1, article id 010402Article in journal (Refereed)
  • 18.
    Hou, Zining
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    An, Yu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hjort, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Sandegren, Linus
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Time lapse investigation of antibiotic susceptibility using a microfluidic linear gradient 3D culture device2014In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 14, no 17, p. 3409-3418Article in journal (Refereed)
    Abstract [en]

    This study reports a novel approach to quantitatively investigate the antibacterial effect of antibiotics on bacteria using a three-dimensional microfluidic culture device. In particular, our approach is suitable for studying the pharmacodynamics effects of antibiotics on bacterial cells temporally and with a continuous range of concentrations in a single experiment. The responses of bacterial cells to a linear concentration gradient of antibiotics were observed using time-lapse photography, by encapsulating bacterial cells in an agarose-based gel located in a commercially available microfluidics chamber. This approach generates dynamic information with high resolution, in a single operation, e. g., growth curves and antibiotic pharmacodynamics, in a well-controlled environment. No pre-labelling of the cells is needed and therefore any bacterial sample can be tested in this setup. It also provides static information comparable to that of standard techniques for measuring minimum inhibitory concentration (MIC). Five antibiotics with different mechanisms were analysed against wild-type Escherichia coli, Staphylococcus aureus and Salmonella Typhimurium. The entire process, including data analysis, took 2.5-4 h and from the same analysis, high-resolution growth curves were obtained. As a proof of principle, a pharmacodynamic model of streptomycin against Salmonella Typhimurium was built based on the maximal effect model, which agreed well with the experimental results. Our approach has the potential to be a simple and flexible solution to study responding behaviours of microbial cells under different selection pressures both temporally and in a range of concentrations.

  • 19.
    Jeong, Seung Hee
    et al.
    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.
    Chen, Si
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden..
    Huo, Jinxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Gamstedt, Erik Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Liu, Johan
    Chalmers, Dept Microtechnol & Nanosci MC2, SE-41296 Gothenburg, Sweden..
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 18257Article in journal (Refereed)
    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.

  • 20.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Chen, Si
    Chalmers University of Technology.
    Huo, Jinxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Gravier, Laurent
    University of Applied Sciences and Arts Western Switzerland.
    Gamstedt, Erik Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Liu, Johan
    Chalmers University of Technology.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan, Peoples R China.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Thermal Elastomer Composites for Soft Transducers2015Conference paper (Refereed)
    Abstract [en]

    There is a need for thermal elastomer composites (TEC) which are stretchable, electrically insulating and easily processablefor soft and stretchable sensor or actuator systems as a thermal conductor or heat spreader at an interface or in a package.A novel TEC was made by embedding a gallium based liquid alloy (Galinstan) as a droplet in polydimethylsiloxane (PDMS,Elastosil RT 601) matrix with a high speed mechanical mixing process.

  • 21.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Cruz, Javier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Chen, Si
    Chalmers, Dept Microtechnol & Nanosci MC2, Kemivagen 9, SE-41296 Gothenburg, Sweden.
    Gravier, Laurent
    Univ Appl Sci & Arts Western Switzerland, Inst Micro & Nano Tech, CH-1401 Yverdon, Switzerland.
    Liu, Johan
    Chalmers, Dept Microtechnol & Nanosci MC2, Kemivagen 9, SE-41296 Gothenburg, Sweden.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stretchable thermoelectric generators metallized with liquid alloy2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 18, p. 15791-15797Article in journal (Refereed)
    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.

  • 22.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Cruz, Javier
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Zhang, Zhibin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Soft Bendable Thermoelectric Generator for Uneven Surface Implementation2015In: 26th Micromechanics and Microsystems Europe Workshop, 2015, p. A8-Conference paper (Other academic)
  • 23.
    Jeong, Seung Hee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Hagman, Anton
    KTH, Hållfasthetslära, Stockholm.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Sundqvist, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Wu, Zhigang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Liquid alloy printing of microfluidic stretchable electronics2012In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 22, no 12, p. 4657-4664Article in journal (Refereed)
    Abstract [en]