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  • 1.
    Dånmark, Staffan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Gladnikoff, Micha
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Frisk, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Zelenina, Marina
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Mustafa, Kamal
    Russom, Aman
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Development of a novel microfluidic device for long-term in situ monitoring of live cells in 3-dimensional matrices2012In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 14, no 5, p. 885-893Article in journal (Refereed)
    Abstract [en]

    Using the latest innovations in microfabrication technology, 3-dimensional microfluidic cell culture systems have been developed as an attractive alternative to traditional 2-dimensional culturing systems as a model for long-term microscale cell-based research. Most microfluidic systems are based on the embedding of cells in hydrogels. However, physiologically realistic conditions based on hydrogels are difficult to obtain and the systems are often too complicated. We have developed a microfluidic cell culture device that incorporates a biodegradable rigid 3D polymer scaffold using standard soft lithography methods. The device permits repeated high-resolution fluorescent imaging of live cell populations within the matrix over a 4 week period. It was also possible to track cell development at the same spatial location throughout this time. In addition, human primary periodontal ligament cells were induced to produce quantifiable calcium deposits within the system. This simple and versatile device should be readily applicable for cell-based studies that require long-term culture and high-resolution bioimaging.

  • 2.
    Faridi, Muhammad Asim
    et al.
    KTH. mafaridi@kth.se.
    Iranmanesh, Ida Sadat
    KTH.
    Ramachandraiah, Harisha
    Vanderleyden, Els
    Dubruel, Peter
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Glass Capillary based cavity resonator for particle trapping study and bacteria up-concentrationIn: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781Article in journal (Refereed)
    Abstract [en]

    We have performed particle aggregation characterization on the basis of their material and suspending

    medium in a capillary-based cavity resonator used for acoustophoresis. We have investigated the experimental

    aggregation time of 5μm polystyrene and silica particles, size of aggregate, number of trapped particles and upconcentration

    factor in water, 0.01M phosphate buffered saline (PBS) and 0.005M PBS at 1.97MHz and with

    actuation voltages between 4, 8 and 12Vpp. We have found that there is little difference between using water and

    PBS as suspension medium, approximately 5-10% longer trapping times with PBS compared with water.

    However we get approx. 5.5 times faster trapping time for silica than for polystyrene. It is also observed and

    calculated that silica particle aggregates have 3.4 times larger area than the polystyrene aggregates using the same

    starting particle concentrations, revealing similar amount of difference in trapped number of particles. The upconcentration

    factor for silica is also about 3.2 times higher than that of polystyrene due to larger aggregate area

    of silica particles. Based on theoretical predictions and experimental characterization of the particle aggregation

    pattern, we note that the particle-particle interaction force contribution to the total acoustic radiation force is more

    pronounced for silica than for polystyrene. Finally as a proof of principle for biomedical sample preparation

    application we demonstrate the capillary-based silica particles mediated bacteria acoustophoretic upconcentration.

    This setup could potentially be utilized not only for sample preparation application but also for

    bead based affinity immunoassays.

  • 3.
    Faridi, Muhammad Asim
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab. mafaridi@kth.se.
    Ramachandraiah, Harisha
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Iranmanesh, Ida Sadat
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    MicroBubble Activated Acoustic Cell Sorting: BAACSIn: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781Article in journal (Refereed)
    Abstract [en]

    Acoustophoresis, the ability to acoustically manipulate particles and cells inside a microfluidic channel, is a critical enabling technology for cell-sorting applications. However, one of the major impediments for routine use of acoustophoresis at clinical laboratory has been the reliance on the inherent physical properties of cells for separation. Here, we present a microfluidic-based microBubble-Activated Acoustic Cell Sorting (BAACS) method that rely on the specific binding of target cells to microbubbles conjugated with specific antibodies on their surface for continuous cell separation using ultrasonic standing wave. In acoustophoresis, cells being positive acoustic contrast particles migrate to pressure nodes. On the contrary we show that air-filled polymer-shelled microbubbles being strong negative acoustic contrast particles migrate to pressure antinodes at acoustic pressure amplitudes as low as 60 kPa. As a proof of principle, using the BAACS strategy, we demonstrate the separation of cancer cell line in a suspension with better than 75% efficiency. Moreover, 100% of the microbubble-cell conjugates migrated to the anti-node. Hence a better upstream affinity-capture has the potential to provide higher sorting efficiency. The BAACS technique may potentially provide a simplistic approach for similar sized selective isolation of cells, and is suited for applications in point of care.

  • 4.
    Faridi, Muhammad Asim
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab. mafaridi@kth.se.
    Ramachandraiah, Harisha
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Iranmanesh, Ida Sadat
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    MicroBubble Activated Acoustic Cell Sorting: BAACS2017In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 19, no 2, article id 23Article in journal (Refereed)
    Abstract [en]

    Acoustophoresis, the ability to acoustically manipulate particles and cells inside a microfluidic channel, is a critical enabling technology for cell-sorting applications. However, one of the major impediments for routine use of acoustophoresis at clinical laboratory has been the reliance on the inherent physical properties of cells for separation. Here, we present a microfluidic-based microBubble-Activated Acoustic Cell Sorting (BAACS) method that rely on the specific binding of target cells to microbubbles conjugated with specific antibodies on their surface for continuous cell separation using ultrasonic standing wave. In acoustophoresis, cells being positive acoustic contrast particles migrate to pressure nodes. On the contrary we show that air-filled polymer-shelled microbubbles being strong negative acoustic contrast particles migrate to pressure antinodes at acoustic pressure amplitudes as low as 60 kPa. As a proof of principle, using the BAACS strategy, we demonstrate the separation of cancer cell line in a suspension with better than 75% efficiency. Moreover, 100% of the microbubble-cell conjugates migrated to the anti-node. Hence a better upstream affinity-capture has the potential to provide higher sorting efficiency. The BAACS technique may potentially provide a simplistic approach for similar sized selective isolation of cells, and is suited for applications in point of care.

  • 5.
    Frisk, Thomas
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Khorshidi, Mohammad Ali
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Guldevall, Karolin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Vanherberghen, Bruno
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    A silicon-glass microwell platform for high-resolution imaging and high-content screening with single cell resolution2011In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 13, no 4, p. 683-693Article in journal (Refereed)
    Abstract [en]

    We present a novel microwell array platform suited for various cell-imaging assays where single cell resolution is important. The platform consists of an exchangeable silicon-glass microchip for cell biological applications and a custom made holder that fits in conventional microscopes. The microchips presented here contain arrays of miniature wells, where the well sizes and layout have been designed for different applications, including single cell imaging, studies of cell-cell interactions or ultrasonic manipulation of cells. The device has been designed to be easy to use, to allow long-term assays (spanning several days) with read-outs based on high-resolution imaging or high-content screening. This study is focused on screening applications and an automatic cell counting protocol is described and evaluated. Finally, we have tested the device and automatic counting by studying the selective survival and clonal expansion of 721.221 B cells transfected to express HLA Cw6-GFP compared to untransfected 721.221 B cells when grown under antibiotic selection for 3 days. The device and automated analysis protocol make up the foundation for development of several novel cellular imaging assays.

  • 6.
    Iranmanesh, Ida
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Ohlin, Mathias
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Ramachandraiah, Harisha
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Ye, Simon
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Acoustic micro-vortexing of fluids, particles and cells in disposable microfluidic chips2016In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 18, no 4, article id 71Article in journal (Refereed)
    Abstract [en]

    We demonstrate an acoustic platform for microvortexing in disposable polymer microfluidic chips with small-volume (20 mu l) reaction chambers. The described method is demonstrated for a variety of standard vortexing functions, including mixing of fluids, re-suspension of a pellet of magnetic beads collected by a magnet placed on the chip, and lysis of cells for DNA extraction. The device is based on a modified Langevin-type ultrasonic transducer with an exponential horn for efficient coupling into the microfluidic chip, which is actuated by a low-cost fixed-frequency electronic driver board. The transducer is optimized by numerical modelling, and different demonstrated vortexing functions are realized by actuating the transducer for varying times; from fractions of a second for fluid mixing, to half a minute for cell lysis and DNA extraction. The platform can be operated during 1 min below physiological temperatures with the help of a PC fan, a Peltier element and an aluminum heat sink acting as the chip holder. As a proof of principle for sample preparation applications, we demonstrate on-chip cell lysis and DNA extraction within 25 s. The method is of interest for automating and chip-integrating sample preparation procedures in various biological assays.

  • 7. Javanmard, Mehdi
    et al.
    Babrzadeh, Farbod
    KTH, School of Biotechnology (BIO), Biochemistry.
    Nyrén, Pål
    KTH, School of Biotechnology (BIO), Biochemistry.
    Davis, Ronald W.
    Improvement in cell capture throughput using parallel bioactivated microfluidic channels2012In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 14, no 4, p. 625-629Article in journal (Refereed)
    Abstract [en]

    Optimization of targeted cell capture with microfluidic devices continues to be a challenge. On the one hand, microfluidics allow working with microliter volumes of liquids, whereas various applications in the real world require detection of target analyte in large volumes, such as capture of rare cell types in several ml of blood. This contrast of volumes (microliter vs. ml) has prevented the emergence of microfluidic cell capture sensors in the clinical setting. Here, we study the improvement in cell capture and throughput achieved using parallel bioactivated microfluidic channels. The device consists of channels in parallel with each other tied to a single channel. We discuss fabrication and testing of our devices, and show the ability for an improvement in throughput detection of target cells.

  • 8.
    Johansson, Linda
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. Department of Engineering Sciences, Ångström Laboratory, Uppsala University, PO Box 534, SE-75121, Uppsala, Sweden.
    Enlund, J.
    Johansson, S.
    Katardjiev, I.
    Yantchev, V.
    Surface acoustic wave induced particle manipulation in a PDMS channel-principle concepts for continuous flow applications2012In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 14, no 2, p. 279-289Article in journal (Refereed)
    Abstract [en]

    A device for acoustic particle manipulation in the 40 MHz range for continuous-flow operation in a 50 ÎŒm wide PDMS channel has been evaluated. Unidirectional interdigital transducers on a Y-cut Z-propagation lithium nixobate wafer were used to excite a surface acoustic wave that generated an acoustic standing wave inside the microfluidic channel. It was shown that particle alignment nodes with different inter-node spacing could be obtained, depending on device design and driving frequency. The observed inter-node spacing differed from the standard halfwavelength inter-node spacing generally employed in bulk acoustic transducer excited resonant systems. This effect and the related issue of acoustic node positions relative the channel walls, which is fundamental for most continuous flow particle manipulation operations in channels, was evaluated in measurements and simulations. Specific applications of particle separation and alignment where these systems can offer benefits relative state-of the art designs were identified.

  • 9.
    Johansson, Staffan B.
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Eklund, Anders
    Malm, Jan
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    A MEMS-based passive hydrocephalus shunt for body position controlled intracranial pressure regulation2014In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 16, no 4, p. 529-536Article in journal (Refereed)
    Abstract [en]

    This paper reports a novel micro electro mechanical system (MEMS) valve with posture controlled flow characteristics for improved treatment of hydrocephalus, a disease that is characterized by elevated pressure in the cerebrospinal fluid (CSF) that surrounds the brain and spinal cord. In contrast to conventional differential pressure CSF valves, the CSF valve presented here features a third port which utilizes hydrostatic pressure from a pressure compensating catheter to adapt CSF drainage to optimized levels irrespective of body position. Prototypes have been fabricated using standard MEMS manufacturing processes and the experimental evaluation successfully showed that the flow rate was adjustable with a varying hydrostatic pressure on the third port. Measured data showed that flow rate was at near ideal values at laying body position and that the flow rate can be adjusted to optimal values at standing body position by selecting an appropriate length of the pressure compensating catheter. This is the first pressure balanced CSF valve intended for body position controlled CSF pressure regulation.

  • 10.
    Kawakita, Satoru
    et al.
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Li, Shaopei
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Nguyen, Huu Tuan
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Maity, Surjendu
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Haghniaz, Reihaneh
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Bahari, Jamal
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Yu, Ning
    Univ Calif Riverside, Dept Chem & Environm Engn, Riverside, CA 92521 USA.
    Mandal, Kalpana
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Bandaru, Praveen
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Mou, Lei
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Ermis, Menekse
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Khalil, Enam
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA; Univ Jordan, Sch Pharm, Amman 11942, Jordan.
    Khosravi, Safoora
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA; Univ British Columbia, Dept Elect & Comp Engn, Vancouver, BC V6T1Z4, Canada.
    Peirsman, Arne
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA; Univ Ghent, Dept Plast Aesthet & Reconstruct Surg, B-9000 Ghent, Belgium; Univ Ghent, Lab Expt Canc Res, B-9000 Ghent, Belgium.
    Nasiri, Rohollah
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab. Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Adachi, Annie
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA; Univ Calif San Francisco, Cardiovasc Res Inst, San Francisco, CA 94158 USA.
    Nakayama, Aya
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA; CALTECH, Div Chem & Chem Engn, Pasadena, CA 91125 USA.
    Bell, Remy
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA; Univ South Carolina, Coll Engn & Comp, Dept Biomed Engn, Columbia, SC 29208 USA.
    Zhu, Yangzhi
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Jucaud, Vadim
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Dokmeci, Mehmet Remzi
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Khademhosseini, Ali
    Terasaki Inst Biomed Innovat, Los Angeles, CA 90064 USA.
    Rapid integration of screen-printed electrodes into thermoplastic organ-on-a-chip devices for real-time monitoring of trans-endothelial electrical resistance2023In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 25, no 4, article id 37Article in journal (Refereed)
    Abstract [en]

    Trans-endothelial electrical resistance (TEER) is one of the most widely used indicators to quantify the barrier integrity of endothelial layers. Over the last decade, the integration of TEER sensors into organ-on-a-chip (OOC) platforms has gained increasing interest for its efficient and effective measurement of TEER in OOCs. To date, microfabricated electrodes or direct insertion of wires has been used to integrate TEER sensors into OOCs, with each method having advantages and disadvantages. In this study, we developed a TEER-SPE chip consisting of carbon-based screen-printed electrodes (SPEs) embedded in a poly(methyl methacrylate) (PMMA)-based multi-layered microfluidic device with a porous poly(ethylene terephthalate) membrane in-between. As proof of concept, we demonstrated the successful cultures of hCMEC/D3 cells and the formation of confluent monolayers in the TEER-SPE chip and obtained TEER measurements for 4 days. Additionally, the TEER-SPE chip could detect changes in the barrier integrity due to shear stress or an inflammatory cytokine (i.e., tumor necrosis factor-& alpha;). The novel approach enables a low-cost and facile fabrication of carbon-based SPEs on PMMA substrates and the subsequent assembly of PMMA layers for rapid prototyping. Being cost-effective and cleanroom-free, our method lowers the existing logistical and technical barriers presenting itself as another step forward to the broader adoption of OOCs with TEER measurement capability.

  • 11. Komen, Job
    et al.
    Wolbers, Floor
    Franke, Henk R.
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Proteomics.
    Vermes, Istvan
    van den Berg, Albert
    Viability analysis and apoptosis induction of breast cancer cells in a microfluidic device: effect of cytostatic drugs2008In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 10, no 5, p. 727-737Article in journal (Refereed)
    Abstract [en]

    Breast cancer is the leading cause of cancer deaths among non-smoking women worldwide. At the moment the treatment regime is such that patients receive different chemotherapeutic and/or hormonal treatments dependent on the hormone receptor status, the menopausal status and age. However, in vitro sensitivity testing of tumor biopsies could rationalize and improve the choice of chemo-and hormone therapy. Lab-on-a-Chip devices, using microfluidic techniques, make detailed cellular analysis possible using fewer cells, enabling working with a patients' own cells and performing chemo-and hormone sensitivity testing in an ex vivo setting. This article describes the development of two microfluidic devices made in poly(dimethylsiloxane) PDMS) to validate the cell culture properties and analyze the chemosensitivity of MCF-7 cells (estrogen receptor positive human breast cancer cells) in response to the drug staurosporine (SSP). In both cases, cell viability was assessed using the life-stain Calcein-AM (CAAM) and the death dye propidium iodide (PI). MCF-7 cells could be statically cultured for up to 7 days in the microfluidic chip. A 30 min flow with SSP and a subsequent 24 h static incubation in the incubator induced apoptosis in MCF-7 cells, as shown by a disappearance of the aggregate-like morphology, a decrease in CAAM staining and an increase in PI staining. This work provides valuable leads to develop a microfluidic chip to test the chemosensitivity of tumor cells in response to therapeutics and in this way improve cancer treatment towards personalized medicine.

  • 12.
    Last, Torben
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Winkler, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems. Tech Univ Carolo Wilhelmina Braunschweig, Braunschweig, Germany..
    Stemme, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems. Karolinska Univ Hosp, Bioclinicum, Solna, Sweden..
    Self-sealing MEMS spray-nozzles to prevent bacterial contamination of portable inhalers for aqueous drug delivery2022In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 24, no 3, article id 25Article in journal (Refereed)
    Abstract [en]

    Pulmonary drug delivery by portable inhalers is the gold standard in lung disease therapy. An increasing focus on environmentally friendly inhalation currently spurs the development of propellant-free devices. However, the absence of propellants in the drug creates a need for suitable sealing systems that can ensure the pathogenic safety of devices. Traditionally, liquid drug inhalers incorporate a spray nozzle and a separate check valve. Here we show a fully integrated MEMS -based spray system for aqueous drug solutions and demonstrate its bacterial safety. The device comprises a thin silicon membrane with spray orifices, which self-seal against a compliant parylene valve seat underneath. This sealing system prevents bacterial ingrowth in its default closed state, while actuation lifts the membrane from the valve seat upon pressurization and sprays an inhalable aerosol from the nozzles. To seal against bacterial contamination effectively, we found that a contact force between the valve seat and the membrane (featuring the spray nozzles) is needed. In our testing, both self-sealing and an otherwise identical unvalved version of the spray chip can be bacterially safe in continued use when thoroughly cleaned of excess fluids and subjected to low bacterial loads for brief periods. However, when directly exposed to 10(7) CFU/ml of our test organism Citrobacter rodentium for 24 h, unvalved systems become contaminated in nearly 90% of cases. In contrast, self-sealing spray chips reduced contamination probability by 70%. This development may enable preservative-free drug formulations in portable inhalers that use propellant-free aqueous drug solutions.

  • 13.
    Marques, Filipe
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Absorbable cyst brushes2023In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 25, no 3Article in journal (Refereed)
    Abstract [en]

    Cytobrushes are used for low-invasive sample collection and screening in multiple diseases, with a significant impact on early detection, prevention, and diagnosis. This study focuses on improving the safety of cell brushing in hard-to-reach locations by exploring brush construction from absorbable materials. We investigated the efficacy of loop brushes made of absorbable suture wires of Chirlac, Chirasorb, Monocryl, PDS II, Vicryl Rapid, Glycolon, and Catgut during their operation in conjunction with fine-needle aspiration in an artificial cyst model. PDS II brushes demonstrated the highest efficiency, while Monocryl and Catgut also provided a significant brushing effect. Efficient brushes portrayed higher flexural rigidity than their counterparts, and their efficiency was inversely proportional to their plastic deformation by the needle. Our results open avenues for safer cell biopsies in hard-to-reach locations by utilizing brushes composed of absorbable materials.

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  • 14.
    Ribet, Federico
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Real-time intradermal continuous glucose monitoring using a minimally invasive microneedle-based system2018In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 20, no 4, article id 101Article in journal (Refereed)
    Abstract [en]

    Continuous glucose monitoring (CGM) has the potential to greatly improve diabetes management. The aim of this work is to show a proof-of-concept CGM device which performs minimally invasive and minimally delayed in-situ glucose sensing in the dermal interstitial fluid, combining the advantages of microneedle-based and commercially available CGM systems. The device is based on the integration of an ultra-miniaturized electrochemical sensing probe in the lumen of a single hollow microneedle, separately realized using standard silicon microfabrication methods. By placing the sensing electrodes inside the lumen facing an opening towards the dermal space, real-time measurement purely can be performed relying on molecular diffusion over a short distance. Furthermore, the device relies only on passive capillary lumen filling without the need for complex fluid extraction mechanisms. Importantly, the transdermal portion of the device is 50 times smaller than that of commercial products. This allows access to the dermis and simultaneously reduces tissue trauma, along with being virtually painless during insertion. The three-electrode enzymatic sensor alone was previously proven to have satisfactory sensitivity (1.5 nA/mM), linearity (up to 14 mM), selectivity, and long-term stability (up to 4 days) in-vitro. In this work we combine this sensor technology with microneedles for reliable insertion in forearm skin. In-vivo human tests showed the possibility to correctly and dynamically track glycaemia over time, with approximately 10 min delay with respect to capillary blood control values, in line with the expected physiological lag time. The proposed device can thus reduce discomfort and potentially enable less invasive real-time CGM in diabetic patients.

  • 15.
    Roxhed, Niclas
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Griss, Patrick
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Membrane-sealed Hollow Microneedles and Related Administration Schemes for Transdermal Drug Delivery2008In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 10, no 2, p. 271-279Article in journal (Refereed)
    Abstract [en]

    This paper presents fabrication and testing of membrane-sealed hollow microneedles. This novel concept offers the possibility of a sealed microneedle-based transdermal drug delivery system in which the drug is stored and protected from the environment. Sealed microneedles were fabricated by covering the tip openings of out-of-plane silicon microneedles with thin gold membranes. In this way a leak-tight seal was established which hinders both contamination and evaporation. To allow drug release from the microneedles, three different methods of opening the seals were investigated: burst opening by means of pressure; opening by applying a small voltage in the presence of physiological saline; and opening as a result of microneedle insertion into the skin. It was found that a 170 nm thick gold membrane can withstand a pressure of approximately 120 kPa. At higher pressures the membranes burst and the microneedles are opened up. The membranes can also be electrochemically dissolved within 2 min in saline conditions similar to interstitial fluid present in the skin. Moreover, through in vivo tests, it was demonstrated that 170 nm thick membranes break when the microneedles were inserted into skin tissue. The proposed concept was demonstrated as a feasible option for sealing hollow microneedles. This enables the realization of a closed-package transdermal drug delivery system based on microneedles.

  • 16.
    Rydholm, Susanna
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Frisk, Thomas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Kowalewski, Jacob M
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Andersson Svahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Microfluidic devices for studies of primary cilium mediated cellular response to dynamic flow conditions2008In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 10, no 4, p. 555-560Article in journal (Refereed)
    Abstract [en]

    We present the first microfabricated microfluidic devices designed specifically for studies of primary cilium mediated cellular response to dynamic flow. The primary cilium functions as a mechano-sensor in renal tubular epithelium, sensing the extracellular fluid flow. Malfunction of cilia has been implicated in e.g. polycystic kidney disease and other pathological conditions. Bending of the primary cilium by fluid flow has been shown to give rise to an intracellular calcium signal, however little is known about the sensitivity to flow duration, magnitude and direction. This paper presents a novel method for studying cilia forming cells in asymmetric microfluidic environments. The microfluidic devices presented here were designed for a dynamic control of the local fluid flow on a cellular level, and thus, enables studies of cellular responses to an amplitude, frequency and direction controlled cilium movement.

  • 17.
    Samel, Björn
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Nock, Volker
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Russom, Aman
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Griss, Patrick
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    A Disposable Lab-on-a-chip Platform with Embedded Fluid Actuators for Active Nanoliter Liquid Handling2007In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 9, no 1, p. 61-67Article in journal (Refereed)
    Abstract [en]

    In this work we present the development of a disposable liquid handling lab-on-a-chip (LOC) platform with embedded actuators for applications in analytical chemistry. The proposed platform for nanoliter liquid handling is based on a thermally responsive silicone elastomer composite, consisting of PDMS and expandable microspheres. In our LOC platform, we integrate active dosing, transportation and merging of nanoliter liquid volumes. The disposable platform successfully demonstrates precise sample volume control with smart microfluidic manipulation and on-chip active microfluidic components. It is entirely fabricated from low-cost materials using wafer-level processing. Moreover, an enzymatic reaction and real-time detection was successfully conducted to exemplify its applicability as an LOC.

1 - 17 of 17
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