| 1. |
- Cruz, Javier, 1990-, et al.
(författare)
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Stable 3D Inertial Focusing by High Aspect Ratio Curved Microfluidics
- 2021
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Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 31
-
Tidskriftsartikel (refereegranskat)abstract
- Fine manipulation of particles is essential for the analysis of complex samples such as blood or environmental water, where rare particles of interest may be masked by millions of others. Inertial focusing is amongst the most promising techniques for this task, enabling label-free manipulation of particles with sub-micron resolution at very high flow rates. However, the phenomenon still remains difficult to predict due to the focus position shifting in tortuous ways as function of the channel geometry, flow rate and particle size. Here, we present a new line of microfluidics that exploit inertial focusing in High Aspect Ratio Curved (HARC) microchannels and overcome this limitation. Consisting of a single curved channel, HARC systems provide a highly predictable, single focus position near the centre of the inner wall, largely independent of the flow rate and particle size.An explanation of the mechanism of migration and focus of particles, together with its governing equations, is provided based on simulations in COMSOL Multiphysics and experimental results. HARC microchannels built in silicon-glass were used for experimental validation, achieving a high quality, single focus position for a range of microparticles with sizes of 0.7 - 1 µm and bacterial cells (Escherichia coli). The recovery of 1 µm particles was 99.84% with a factor four in concentration.With a stable focus position, we envision that HARC systems will bring the technology closer to implementation in laboratories for analysis of complex fluids with biological particles like cells and organelles.
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| 2. |
- Jeong, Seung Hee, et al.
(författare)
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Plåster med sträckbara trådlösa givare för medicinsk teknik
- 2015
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Ingår i: Abstracts Medicinteknikdagarna 2015. ; , s. 59-
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Konferensbidrag (refereegranskat)abstract
- Målet med denna presentation är att visa på olika möjligheter för sträckbara trådlösa givare för medicinsk teknik. Vi söker läkare och företag som är intresserade av detta.Elektronikbranschen förutspår en massiv ökning av trådlösa sensorsystem inom en snar framtid och ett ”Sakernas Internet”. En av de stora utvecklingsområdena här är bärbara tillbehör; trådlösa sensornoder i kroppsnära nätverk som kommunicerar med en smartphone. Men det finns en generation efter detta och många förutspår att det kommer att vara nätverk med trådlösa givare och kommunikationsnoder som är i direktkontakt med kroppen, på huden eller som implantat. Det är här töjbar elektronik kommer att sätta sin prägel då dess mjuka, följsamma och sträckbara folier med givare och elektronik erbjuder en oöverträffad mekanisk koppling till vår hud och våra organ.Den mest uppmärksammade tekniken är den s.k. elastiska elektroniken, vilken utgår från ultratunna, och därmed flexibla, integrerade kretsar som överförs till elastiska substrat. Det möjliggör väldigt tunna system som kan ha samma höga upplösning och täthet av komponenter som annan mikroelektronik1. Detta passar väl till mindre strukturer men har flera svagheter vid tillverkning av system där större och tjockare komponenter krävs. Här har vi i stället utvecklat sträckbara kretskort med en flytande metall som ledare och kontakter. De främsta fördelarna med flytande ledare är att en vätska följer med alla formändringar utan motstånd och att små styva komponenter kan modulärt monteras och kontakteras till ledaren utan att kontakter bryts när den utsätts för en större töjning – istället kommer komponentens kontakt att glida på vätskan2. Vi har redan visat att vi idag kan producera avancerade kretsar med flera lager av ledare och monterade små komponenter för olika trådlösa system med töjningsgivare, RFID, trådlös energiöverföring, termoelektriska komponenter, mm.I denna presentation visar vi hur kan tillverka intelligenta och trådlösa sträckbara plåster med olika givare för att läsa av värmeflödet från en kropp. Vi tror dock att det är lätt för oss att göra andra typer av givare eller montera små chip av kommersiella givare och transdermala elektroder för andra medicinska tillämpningar. Vi behöver dock samverka med läkare och medicinsktekniska företag för att välja och pröva de bäst lämpade givarna.
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| 3. |
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| 4. |
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| 5. |
- Ali, M., et al.
(författare)
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Reduced photoluminescence from InGaN/GaN multiple quantum well structures following 40 MeV iodine ion irradiation
- 2009
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Ingår i: Physica. B, Condensed matter. - : Elsevier. - 0921-4526 .- 1873-2135. ; 404:23-24, s. 4925-4928
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Tidskriftsartikel (refereegranskat)abstract
- The effects following ion irradiation of GaN-based devices are still limited. Here we present data on the photoluminescence (PL) emitted from InGaN/GaN multiple quantum well (MQW) structures, which have been exposed to 40 MeV I ion irradiation. The PL is reduced as a function of applied ion fluence, with essentially no PL signal left above 1011 ions/cm2. It is observed that even the ion fluences in the 109 ions/cm2 range have a pronounced effect on the photoluminescence properties of the MQW structures. This may have consequences concerning application of InGaN/GaN MQW’s in radiation-rich environments, in addition to defect build-up during ion beam analysis.
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| 6. |
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| 7. |
- Andersson, Martin, et al.
(författare)
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Dynamic pH determination at high pressure of aqueous additive mixtures in contact with dense CO2
- 2018
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446 .- 1872-8162. ; 136, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- A system consisting of a high-pressure tolerant microfluidic glass chip, high-speed absorbance imaging, and image processing has been developed to study rapid dynamic events like pH change in a multiphase flow. The system gives both kinetic and quantitative equilibrated information. By tracking the interactions of aqueous additive mixtures and liquid CO2, at 80 bar and 24 °C, under flow, measurement at a given P, T condition is done in 0.25 s. The acidification rate to steady state was found to be mass transport limited, occurring in less than 1 s. For 30 mM of the additives ammonium acetate and ammonium formate, equilibrium pH of 4.5 and 4.1, respectively, was seen. These additives are of key importance in common mobile phases used in SFC.
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| 8. |
- Andersson, Martin, et al.
(författare)
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Microfluidics for High-Pressure Analyses
- 2018
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Ingår i: 12<sup>th</sup> Micronano System Workshop (MSW 2018, May 14-15, 2018, Espoo, Finland). ; , s. 8-8
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Konferensbidrag (refereegranskat)abstract
- When using appropriate materials and microfabrication techniques, the small dimensionsand mechanical stability of microstructured devices allow for processes at high pressureswithout loss in safety. The largest area of applications has been demonstrated in chemistry,where extraction, synthesis and analyses often excel at high densities and high temperatures.These two parameters are accessible through high pressures. Capillary chemistry has beenused since long but, just like in low-pressure applications, there are several advantages in usingmicrofluidic platforms for control of reactions, catalysis, mixing and separation. For example,planar isothermal set-ups, large local variations in geometries, dense form factors, small deadvolumes and precisely positioned microstructures.In analytical systems, we are studying high-pressure components and microsystems forsampling, sample preparation, analyses and fractionation. We will present what drives ourresearch and development: Our experimental set-up with high-pressure pumps, high-speedcamera, sensors, valves, piston-chambers, backpressure regulators, cooling table, etc. How wehave built capability in pumping and valving by the use of stainless steel and paraffinactuation. How we are making high pressure silicon-glass and glass-glass chips with integratedelectrical thin film sensors, using printed circuit boards to ease handling of the chips andintegrating modules. A set of relevant publications are listed below.
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| 9. |
- Bjerketorp, J., et al.
(författare)
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Rapid lab-on-a-chip profiling of human gut bacteria
- 2008
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Ingår i: Journal of Microbiological Methods. - : Elsevier BV. - 0167-7012 .- 1872-8359. ; 72:1, s. 82-90
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Tidskriftsartikel (refereegranskat)abstract
- The human gut microbiota has a substantial impact on human health. Different factors such as disease, diet and drug use can have significant impacts on the gut microbiota. Therefore, it is of interest to have simple, rapid methods for analysis of the composition of the gut microbiota for clinical diagnostic purposes. Since only a minor fraction of the gastrointestinal bacterial community is presently possible to cultivate, molecular approaches are currently the best suited to investigate its composition. However, most of these molecular approaches require technical expertise and expensive equipment to run and they are not routinely available. Ideally, the analyses should be point-of-care options that can be run on a chip. In this study, an existing lab-on-chip (LOC) system for sizing/quantifying DNA was combined with length heterogeneity PCR (LH-PCR), a PCR-based profiling method targeting bacterial 16S rRNA gene sequences, to develop a fast, straightforward, reproducible, and economical method for profiling bacterial communities. The LOC LH-PCR method was first evaluated using a standardized gut cocktail containing genomic DNA from eight different bacterial species representing different genera of relevance for human health. The method was also tested on DNA that was directly extracted from human faecal samples and it was consistently capable of detecting alterations in the bacterial samples before and after antibiotic treatment. Although the resolution of the method needs improvement, this study represents the first step towards development of a diagnostic LOC for profiling gut bacterial communities.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Cruz, F. Javier, 1990-, et al.
(författare)
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High pressure inertial focusing for separation and concentration of bacteria at high throughput
- 2017
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Ingår i: 28th Micromechanics and Microsystems Europe Workshop. - : IOP Publishing.
-
Konferensbidrag (refereegranskat)abstract
- Inertial focusing is a phenomenon where particles migrate across streamlines in microchannels and focus at well-defined, size dependent equilibrium points of the cross section. It can be taken into advantage for focusing, separation and concentration of particles at high through-put and high efficiency. As particles decrease in size, smaller channels and higher pressures are needed. Hence, new designs are needed to decrease the pressure drop. In this work a novel design was adapted to focus and separate 1 mu m from 3 mu m spherical polystyrene particles. Also 0.5 mu m spherical polystyrene particles were separated, although in a band instead of a single line. The ability to separate, concentrate and focus bacteria, its simplicity of use and high throughput make this technology a candidate for daily routines in laboratories and hospitals.
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| 16. |
- Cruz, Javier, 1990-, et al.
(författare)
-
Fundamentals of Inertial Focusing in High Aspect Ratio Curved Microfluidics
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Microfluidics exploiting the phenomenon of inertial focusing have attracted much attention in the last decade, as they provide the means to facilitate the detection and analysis of rare particles of interest in complex fluids such as blood and natural water. Although many interesting applications have been demonstrated, the systems remain difficult to engineer. A recently presented line of the technology, inertial focusing in High Aspect Ration Curved (HARC) microfluidics, has the potential to change this and make the benefits of inertial focusing more accessible to the community. In this paper, with experimental evidence and fluid simulations, we provide the two necessary equations to design the systems and successfully focus the desired targets in a single, stable, and high-quality position. Last, the experiments revealed an interesting scaling law of the lift force, which we believe provides a valuable insight into the phenomenon of inertial microfluidics.
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| 17. |
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| 18. |
- Cruz, Javier, 1990-, et al.
(författare)
-
High pressure inertial focusing for separating and concentrating bacteria at high throughput
- 2017
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP PUBLISHING LTD. - 0960-1317 .- 1361-6439. ; 27:8
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 19. |
- Cruz, Javier, 1990-, et al.
(författare)
-
High-resolution Particle Separation by Inertial Focusing in High Aspect Ratio Curved Microfluidics
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The ability to focus, separate and concentrate specific targets in a fluid is essential for the analysis of complex samples such as biological fluids, where a myriad of different particles may be present. Inertial focusing is a very promising technology for such tasks. Recently, inertial focusing in High Aspect Ratio Curved (HARC) microchannels was presented, which simplifies the focusing and concentration of targets by positioning particles close together over a wide range of particle size and flow rate. However, by focusing all particles together, HARC systems lose an essential feature of inertial focusing: the possibility of particle separation by size. Within this work, we report that HARC systems not only do have the capacity to separate particles but can do so with extremely high resolution, which we demonstrate for particles with a size difference down to 80 nm.A model considering the main flow, the secondary flow and a simplified expression for the lift force in HARC microchannels was developed and proven accurate for the prediction of the performance of the systems. The concept was also demonstrated experimentally with three different sub-micron particles (0.79, 0.92 and 1.0 µm in diameter) in silicon-glass microchannels, whose separation distance could be modulated by the radius of the channel.With the capacity to focus sub-micron particles and to separate them with high resolution, inertial focusing in HARC systems are a technology with a strong potential for particle manipulation. We believe that this will facilitate the analysis of complex fluid samples containing bioparticles like bacteria, viruses or eukaryotic organelles.
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| 20. |
- Cruz, Javier, 1990-, et al.
(författare)
-
High-resolution particle separation by inertial focusing in high aspect ratio curved microfluidics
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- The ability to focus, separate and concentrate specific targets in a fluid is essential for the analysis of complex samples such as biological fluids, where a myriad of different particles may be present. Inertial focusing is a very promising technology for such tasks, and specially a recently presented variant, inertial focusing in High Aspect Ratio Curved systems (HARC systems), where the systems are easily engineered and focus the targets together in a stable position over a wide range of particle sizes and flow rates. However, although convenient for laser interrogation and concentration, by focusing all particles together, HARC systems lose an essential feature of inertial focusing: the possibility of particle separation by size. Within this work, we report that HARC systems not only do have the capacity to separate particles but can do so with extremely high resolution, which we demonstrate for particles with a size difference down to 80 nm. In addition to the concept for particle separation, a model considering the main flow, the secondary flow and a simplified expression for the lift force in HARC microchannels was developed and proven accurate for the prediction of the performance of the systems. The concept was also demonstrated experimentally with three different sub-micron particles (0.79, 0.92 and 1.0 mu m in diameter) in silicon-glass microchannels, where the resolution in the separation could be modulated by the radius of the channel. With the capacity to focus sub-micron particles and to separate them with high resolution, we believe that inertial focusing in HARC systems is a technology with the potential to facilitate the analysis of complex fluid samples containing bioparticles like bacteria, viruses or eukaryotic organelles.
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| 21. |
- Cruz, Javier, 1990-, et al.
(författare)
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Inertial focusing of microparticles and its limitations
- 2016
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Ingår i: 27Th Micromechanics And Microsystems Europe Workshop (Mme 2016). - : IOP Publishing.
-
Konferensbidrag (refereegranskat)abstract
- 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.
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| 22. |
- Cruz, Javier, 1990-, et al.
(författare)
-
Inertial focusing with sub-micron resolution for separation of bacteria
- 2019
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Ingår i: Lab on a Chip. - : ROYAL SOC CHEMISTRY. - 1473-0197 .- 1473-0189. ; 19:7, s. 1257-1266
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we study inertial focusing in curved channels and demonstrate the alignment of particles with diameters between 0.5 and 2.0 m, a range of biological relevance since it comprises a multitude of bacteria and organelles of eukaryotic cells. The devices offer very sensitive control over the equilibrium positions and allow two modes of operation. In the first, particles having a large variation in size are focused and concentrated together. In the second, the distribution spreads in a range of sizes achieving separation with sub-micron resolution. These systems were validated with three bacteria species (Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae) showing good alignment while maintaining the viability in all cases. The experiments also revealed that the particles follow a helicoidal trajectory to reach the equilibrium positions, similar to the fluid streamlines simulated in COMSOL, implying that these positions occupy different heights in the cross section. When the equilibrium positions move to the inner wall as the flow rate increases, they are at a similar distance from the centre than in straight channels (approximate to 0.6R), but when the equilibrium positions move to the outer wall as the flow rate increases, they are closer to the centre and the particles pass close to the inner wall to elevate their position before reaching them. These observations were used along with COMSOL simulations to explain the mechanism behind the local force balance and the migration of particles, which we believe contributes to further understanding of the phenomenon. Hopefully, this will make designing more intuitive and reduce the high pressure demands, enabling manipulation of particles much smaller than a micrometer.
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| 23. |
- Cruz, Javier, 1990-
(författare)
-
Microfluidics for High-Pressure Inertial Focusing : Focusing, Separation and Concentration of Micro and Sub-micron Particles
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The birth of microsystems set the ground for technologies never imagined before, for it is not only the small size what characterizes the miniaturized systems, but unique phenomena arise in the micro scale. This thesis relates to one such unique phenomenon, inertial focusing, a phenomenon that occurs in microfluidic systems if very special conditions are met and that allows for fine manipulation of particles in fluid samples. This ability is key in a bigger picture: the analysis of complex fluids, where rare particles of interest may be present in very few numbers amongst a myriad of others, making the task difficult – if not impossible. A system exploiting inertial focusing allows, for instance, to focus, separate, isolate and concentrate such rare particles of interest, and even to transfer them to another fluid, thereby enabling/facilitating their detection and analysis. Examples of rare particles of interest in complex fluids are circulating tumor cells in blood, that give away the presence of cancer, extracellular vesicles also in blood, that contain biomarkers with physiological and pathological information about the patient, or bacteria in natural water, where the species present and their numbers are to be monitored for safety reasons and/or biological studies. This thesis covers the state of art physical principles behind the phenomenon and extends the understanding both in theory and applications. Specifically, the technology is extended to allow for manipulation of sub-micron particles, a range of interest as it comprises bacteria, viruses and organelles of eukaryotic cells. This was possible by an analysis of the balance of forces in play and by the integration of inertial focusing in high-pressure systems (up to 200 bar). In a second block, a very special line of inertial focusing is introduced and developed; inertial focusing in High Aspect Ratio Curved (HARC) microfluidics. These systems, engineered to rearrange the force field responsible for the particle manipulation, not only achieve excellent performances for focusing and concentration of particles, but also extreme resolution in their separation (mathematically unlimited; demonstrated experimentally for differences in size down to 80 nm). Perhaps more important than the performance, the systems are stable, intuitive and simpler to design, attributes that we hope will make the technology and its outstanding benefits more accessible to the community. With its remarkable performance, it would not come as a surprise if, in the near future, inertial focusing makes a strong impact on how analyses are performed nowadays and opens up for possibilities beyond the current state of the art.
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| 24. |
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| 25. |
- Cruz, Javier, 1990-, et al.
(författare)
-
The upper limit and lift force within inertial focusing in high aspect ratio curved microfluidics
- 2021
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Microfluidics exploiting the phenomenon of inertial focusing have attracted much attention in the last decade as they provide the means to facilitate the detection and analysis of rare particles of interest in complex fluids such as blood and natural water. Although many interesting applications have been demonstrated, the systems remain difficult to engineer. A recently presented line of the technology, inertial focusing in High Aspect Ratio Curved microfluidics, has the potential to change this and make the benefits of inertial focusing more accessible to the community. In this paper, with experimental evidence and fluid simulations, we provide the two necessary equations to design the systems and successfully focus the targets in a single, stable, and high-quality position. The experiments also revealed an interesting scaling law of the lift force, which we believe provides a valuable insight into the phenomenon of inertial focusing.
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| 26. |
- Hjort, Klas, 1964-
(författare)
-
Fluidic circuitboard technology
- 2010
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Ingår i: Int Sci Conf on Microfluidics in Bioanalytical Res and Diagnostics. ; , s. 24-
-
Konferensbidrag (refereegranskat)
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| 27. |
- Hjort, Klas, 1964-
(författare)
-
High-pressure microfluidics
- 2017
-
Konferensbidrag (refereegranskat)abstract
- When using appropriate materials and microfabrication techniques, with the small dimensions the mechanical stability of microstructured devices allows for processes at high pressures without loss in safety. The largest area of applications has been demonstrated in green chemistry and bioprocesses, where extraction, synthesis and analyses often excel at high densities and high temperatures, which are accessible through high pressures. Capillary chemistry has been used since long but, just like in low-pressure applications, there are several potential advantages in using microfluidic platforms, e.g., planar isothermal set-ups, large local variations in geometries, dense form factors, small dead volumes and precisely positioned microstructures for control of reactions, catalysis, mixing and separation. Other potential applications are in, e.g., microhydraulics, exploration, gas driven vehicles, and high-pressure science. From a short review of the state-of-art and frontiers of high pressure microfluidics, the focus will be on our different solutions demonstrated for microfluidic handling at high pressures and challenges that remain.
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| 28. |
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| 29. |
- Hjort, Klas, 1964-, et al.
(författare)
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Microfluidic mixing and separation
- 2016
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 26:1
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Tidskriftsartikel (refereegranskat)
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| 30. |
- Hjort, Klas, 1964-, et al.
(författare)
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Micromachining in bulk GaAs
- 1990
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Ingår i: Sensors and materials. - 0914-4935. ; 2, s. 1-
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Tidskriftsartikel (refereegranskat)
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| 31. |
- Hjort, Klas, 1964-
(författare)
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Microsystems for the good life
- 2018
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Ingår i: Int. Summit Forum on Micro and Nano Manipul. and Manufact.. ; , s. 5-5
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Microsystems Technology Division of Uppsala University is committed to make microsystems for the good life. I will present our research on novel materials and technologies for miniaturized systems that are for the good of society and can provide fundamental answers in science.
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| 32. |
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| 33. |
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| 34. |
- Hjort, Klas, 1964-, et al.
(författare)
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Softer, thinner and more compliant implants
- 2018
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Konferensbidrag (refereegranskat)abstract
- Tissue irritation is caused by two main reasons – chemical and mechanical. In recent years, material chemical biocompatibility has been much improved but most implants used in soft tissue still have low compliance. This is especially severe in the brain, where the tissue often has a compliance of a soft hydrogel and ordinary silicone materials like PDMS have an elastic modulus up to 1,000 times higher, i.e. like a wooden stick irritating your skin. Starting from the remaining challenges of the highly successful Cochlear Implants and recent work on stretchable electronics this review conclude on the merits with soft stretchable printed circuitboards, with components of fluids, gels, and sprinkled with a smart dust of small chips.
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| 35. |
- Hjort, Klas, 1964-
(författare)
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Stretchable Microfluidic RF Electronics for Biopatches
- 2016
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Ingår i: 17<sup>th</sup> International Symposium on RF-MEMS and RF-microsystems (MEMSWAVE 2016). ; , s. 8-8
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Konferensbidrag (refereegranskat)abstract
- Silicone based compliant and unobtrusive wireless sensor nodes on the skin, so called biopatches or biostamps, have good potential to revolutionize precision medicine.In much, their promise comes from being unobtrusive in similar manner as contact lenses are compared to eye-glasses. Also, they have intrinsic advantages in their compliancy and direct contact to the body in applications like physical sensors for biomechanical readout, sweat biomarker sensors, optically based non-invasive sensors for various blood stream data, and planar electrophysiological arrays.[i]Our group initiated the use of liquid alloys for stretchable RF-electronics.[ii] The primary objective was to provide large cross-sections with high compliancy for low resistance also in larger areas and components needed in high quality RF-circuits. In addition, the liquid alloy provided a sliding contact to the embedded modules and with that contact robust against large strains. Most recently, we have introduced a very compliant and adhesive PDMS elastomer (named S3-PDMS for soft, stretchable and sticky PDMS), which not only allows for better contact to the skin but also increases the adhesion between the embedded modules and the elastomer.[iii] With these improvements, we now believe that it is possible to make also thicker biopatches unobtrusive, allowing for reusable gadgets, and circuits and devices which demand more volume. At the moment we are investigating how such biopatches should be used in biomechanical medicine. Our technology development is built on batch-wise printed circuit board production with good prospects for medium-sized series. However, to truly revolutionize the precision of precision medicine, the continuous sensoric feedback that supports the medical treatment should be tailored for each person’s needs. Hence, we aim for serial production of very small customized series of sensors as prescribed by your doctor.[i] T.Q. Trung and N.-E. Lee, Flexible and Stretchable Physical Sensor Integrated Platforms for Wearable Human-Activity Monitoring and Personal Healthcare, Adv. Mater. 2016, DOI: 10.1002/adma.201504244; Rugged and breathable forms of stretchable electronics with adherent composites for transcutaneous monitoring, Nature Commun. 2014, 5, 4779; W. Gao, S. Emaminejad, H.Y.Y. Nyein, S. Challa, K. Chen, A. Peck, H.M. Fahad, H. Ota, H. Shiraki, D. Kiriya, D.-H. Lien, G.A. Brooks, R.W. Davis, and A. Javey, Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis, Nature 2016, doi:10.1038/nature16521; H. Lee, T.K. Choi, Y.B. Lee, H.R. Cho, R.Ghaffari, L.Wang, H.J. Choi, T.D.Chung, N.Lu, T. Hyeon, S.H. Choi, and D.-H. Kim, A graphene-based electrochemical device with thermoresponsive microneedles for diabetes monitoring and therapy, Nature Nanotechnology 2016, doi:10.1038/nnano.2016.38 .[ii] S. Cheng, A. Rydberg, K. Hjort and Z. G. Wu, Liquid metal stretchable unbalanced loop antenna, Appl. Phys. Lett. 2009, 94, 144103; Z.G. Wu, K. Hjort, and S.H. Jeong, Microfluidic stretchable radio frequency devices, Proc. IEEE 2015, 103, 1211-1225.[iii] S.H. Jeong, S. Zhang, K. Hjort, Z.G. Wu, Sticky elastomer composite for microfluidic stretchable sensor patches, 2015 MRS Fall Meeting (Nov. 29-Dec. 4, 2015, Boston, MA) B12.04.; S. Jeong, Soft Intelligence - Liquid Matters in Compliant Microsystems, 2016, Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1357, urn:nbn:se:uu:diva-281281
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| 36. |
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| 37. |
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| 38. |
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| 39. |
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| 40. |
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| 41. |
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| 42. |
- Jiao, Mingzhi, et al.
(författare)
-
Comparison of NO2 Gas-Sensing Properties of Three Different ZnO Nanostructures Synthesized by On-Chip Low-Temperature Hydrothermal Growth
- 2018
-
Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 47:1, s. 785-793
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Tidskriftsartikel (refereegranskat)abstract
- Three different ZnO nanostructures, dense nanorods, dense nanowires, and sparse nanowires, were synthesized between Pt electrodes by on-chip hydrothermal growth at 90°C and below. The three nanostructures were characterized by scanning electron microscopy and x-ray diffraction to identify their morphologies and crystal structures. The three ZnO nanostructures were confirmed to have the same crystal type, but their dimensions and densities differed. The NO2 gas-sensing performance of the three ZnO nanostructures was investigated at different operation temperatures. ZnO nanorods had the lowest response to NO2 along with the longest response/recovery time, whereas sparse ZnO nanowires had the highest response to NO2 and the shortest response/recovery time. Sparse ZnO nanowires also performed best at 300°C and still work well and fast at 200°C. The current–voltage curves of the three ZnO nanostructures were obtained at various temperatures, and the results clearly showed that sparse ZnO nanowires did not have the linear characteristics of the others. Analysis of this phenomenon in connection with the highly sensitive behavior of sparse ZnO nanowires is also presented.
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| 43. |
- Jiao, Mingzhi, et al.
(författare)
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Influence of annealing temperature on theperformance and stability of on-chip hydrothermally grown ZnO nanorod gassensor toward NO2
- 2018
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Ingår i: Academia Journal of Scientific Research. - 2315-7712. ; 6:5, s. 180-189
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Tidskriftsartikel (refereegranskat)abstract
- Nanorod-based gas sensors synthesized at low temperature should generally be stabilized by anneling before usage. However, the influence of annealing on the sensing performance and stability of these nanorods is rarely reported. In this study, we first fabricated gas sensors based on ZnO nanorods grown on-chip on glass substrate using hydrothermal method. Subsequently, these sensors were annealed at either 400 °C, 500 °C, or 600 °C in air for 4 h. The gas-sensing performance of the ZnO nanorods toward NO2 was tested before and after annealing. The sensitivity of the gas sensors to NO2 decreased, but the stability increased with the increase in annealing temperature. Photoluminescence spectroscopy and X-ray diffraction were used to investigate the material structure of ZnO nanorods. Results revealed that the oxygen-atom-related defects in the ZnO lattice in the region close to the surface influenced by annealing process were the most significant factors on the sensing properties and stability of ZnO nanorods.
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| 44. |
- Jiao, Mingzhi, et al.
(författare)
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On-chip growth of patterned ZnO nanorod sensors with PdO decoration for enhancement of hydrogen-sensing performance
- 2017
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 42:25, s. 16294-16304
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we used a low-temperature hydrothermal technique to fabricate arrays of sensors with ZnO nanorods grown on-chip. The sensors on the glass substrate then were sputter decorated with Pd at thicknesses of 2, 4, and 8 nm and annealed at 650 °C in air for an hour. Scanning electron microscopy, high resolution transmission microscopy, X-ray diffraction, and surface analysis by X-ray photoelectron spectroscopy characterization demonstrated that decoration of homogenous PdO nanoparticles on the surface of ZnO nanorods had been achieved. The sensors were tested against three reducing gases, namely hydrogen, ethanol, and ammonia, at 350, 400, and 450 °C. The ZnO nanorods decorated with PdO particles from the 2 and 4 nm layers showed the highest responses to H2 at 450 and 350 °C, respectively. These samples also generally exhibited better selectivity for hydrogen than for ethanol and ammonia at the same concentrations and at all tested temperatures. However, the ZnO nanorods decorated with PdO particles from the 8 nm layer showed a reverse sensing behaviour compared with the first two. The sensing mechanism behind these phenomena is discussed in the light of the spillover effect of hydrogen in contact with the PdO particles as well as the negative competition of the PdO thin film formed between the sensor electrodes during sputter decoration, Pd-Zn heterojunction that forms at high temperature and thus influences the conductivity of the ZnO nanorods.
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| 45. |
- Jung, Jiyoung
(författare)
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Investigation of thermal conductivity for liquidmetal composites using the micromechanics-based mean-field homogenization theory
- 2020
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Ingår i: Soft Matter. - 1744-683X .- 1744-6848. ; :25, s. 5840-5847
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Tidskriftsartikel (refereegranskat)abstract
- For the facile use of liquid metal composites (LMCs) for soft, stretchable and thermal systems, it iscrucial to understand and predict the thermal conductivity of the composites as a function of liquidmetal (LM) volume fraction and applied strain. In this study, we investigated the effective thermalconductivity of LMCs based on various mean-field homogenization frameworks including Eshelby, Mori–Tanaka, differential and double inclusion methods. The double inclusion model turned out to make theprediction closest to the experimental results in a wide range of LM volume fractions. Interestingly, wefound that the theoretical models based on the assumption of ideal LM dispersion and zero interfacialresistance underestimated the thermal conductivity compared to the experimental results in a lowvolume fraction regime. By considering the accompanied variations in the LM inclusion’s aspect ratios undera typical size distribution of inclusions (Bmm), the change of effective thermal conductivity was predictedunder a uniaxial 300% tensile strain. Our study will deepen the understanding of the thermal properties ofLMCs and support the designs of stretchable thermal interfaces and packaging with LMCs in the future.
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| 46. |
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| 47. |
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| 48. |
- Köhler, Johan, et al.
(författare)
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A hybrid cold gas microthruster system for spacecraft
- 2001
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Ingår i: Digest of Papers for the 11th Int Conf on Solid-State Sensors and Actuators - Transducers '01 and Eurosensors XV, Munich, Germany, June 10-14. ; , s. 886-889
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Konferensbidrag (refereegranskat)
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| 49. |
- Li, Shiyu, et al.
(författare)
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Docking and Activity of DNA Polymerase on Solid-State Nanopores
- 2022
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Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 7:5, s. 1476-1483
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Tidskriftsartikel (refereegranskat)abstract
- Integration of motor enzymes with biological nanopores has enabled commercial DNA sequencing technology; yet studies of the similar principle applying to solid-state nanopores are limited. Here, we demonstrate the real-life monitoring of phi29 DNA polymerase (DNAP) docking onto truncated-pyramidal nanopore (TPP) arrays through both electrical and optical readout. To achieve effective docking, atomic layer deposition of hafnium oxide is employed to reduce the narrowest pore opening size of original silicon (Si) TPPs to sub-10 nm. On a single TPP with pore opening size comparable to DNAP, ionic current measurements show that a polymerase-DNA complex can temporally dock onto the TPP with a certain docking orientation, while the majority become translocation events. On 5-by-5 TPP arrays, a label-free optical detection method using Ca2+ sensitive dye, are employed to detect the docking dynamics of DNAP. The results show that this label-free detection strategy is capable of accessing the docking events of DNAP on TPP arrays. Finally, we examine the activity of docked DNAP by performing on-site rolling circle amplification to synthesize single-stranded DNA (ssDNA), which serves as a proof-of-concept demonstration of utilizing this docking scheme for emerging nanopore sensing applications.
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| 50. |
- Li, Shiyu, et al.
(författare)
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Dynamics of DNA Clogging in Hafnium Oxide Nanopores
- 2020
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 124:51, s. 11573-11583
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Tidskriftsartikel (refereegranskat)abstract
- Interfacing solid-state nanopores with biological systems has been exploited as a versatile analytical platform for analysis of individual biomolecules. Although clogging of solid-state nanopores due to nonspecific interactions between analytes and pore walls poses a persistent challenge in attaining the anticipated sensing efficacy, insufficient studies focus on elucidating the clogging dynamics. Herein, we investigate the DNA clogging behavior by passing double-stranded (ds) DNA molecules of different lengths through hafnium oxide(HfO2)-coated silicon (Si) nanopore arrays, at different bias voltages and electrolyte pH values. Employing stable and photoluminescent-free HfO2/Si nanopore arrays permits a parallelized visualization of DNA clogging with confocal fluorescence microscopy. We find that the probability of pore clogging increases with both DNA length and bias voltage. Two types of clogging are discerned: persistent and temporary. In the time-resolved analysis, temporary clogging events exhibit a shorter lifetime at higher bias voltage. Furthermore, we show that the surface charge density has a prominent effect on the clogging probability because of electrostatic attraction between the dsDNA and the HfO2 pore walls. An analytical model based on examining the energy landscape along the DNA translocation trajectory is developed to qualitatively evaluate the DNA–pore interaction. Both experimental and theoretical results indicate that the occurrence of clogging is strongly dependent on the configuration of translocating DNA molecules and the electrostatic interaction between DNA and charged pore surface. These findings provide a detailed account of the DNA clogging phenomenon and are of practical interest for DNA sensing based on solid-state nanopores.
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