| 1. |
- Andersson, Martin, et al.
(författare)
-
Microfluidics for High-Pressure Analyses
- 2018
-
Ingår i: 12<sup>th</sup> Micronano System Workshop (MSW 2018, May 14-15, 2018, Espoo, Finland). ; , s. 8-8
-
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.
|
|
| 2. |
- Bocken, Nancy, et al.
(författare)
-
Emergence of carsharing business models and sustainability impacts in Swedish cities
- 2020
-
Ingår i: Sustainability (Switzerland). - : MDPI AG. - 2071-1050. ; 12:4
-
Tidskriftsartikel (refereegranskat)abstract
- The sharing economy has become prominent in the policy, business and academic discourse as a way to achieve greater levels of resource efficiency in sustainability transitions. An example is carsharing, which is regarded as a potential lever for change in sustainable mobility transitions. In this article we, apply the "ecologies of business models" perspective to investigate how carsharing initiatives have coevolved in Sweden. We focus on the city context as a useful unit of analysis to investigate carsharing in four Swedish cities: Gothenburg, Malmo, Stockholm and Umea. Through qualitative case research, we investigate the following: How did carsharing business models coevolve in the studied cities? It was found that early notions of carsharing date back to the 1970s, but the concept has changed significantly over time, particularly with the emergence of (Internet) technology-based platforms. The findings suggest that carsharing is complementary to existing private car usage in cities, rather than a replacement. Based on this, we suggest pathways for local policymakers to consider when implementing sustainable carsharing solutions. The contributions are threefold: providing an empirical study on the theoretical ecologies of business models concept; understanding how carsharing coevolved in Swedish cities and in relation to wider sustainability and mobility trends; and giving novel insight into the role of local governments.
|
|
| 3. |
- Palm, Jenny, et al.
(författare)
-
The role of cities in the sharing economy : Exploring modes of governance in urban sharing practices
- 2019
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 12:24
-
Tidskriftsartikel (refereegranskat)abstract
- Cities have for a long time been key actors in sustainable urban development, and in recent times, also for the sharing economy, as they provide a fertile breeding ground for various sharing initiatives. While some of these initiatives build on existing practices and infrastructures such as public libraries and repair workshops, others require the involvement of private companies, as in the case of car sharing. The sharing economy might therefore require a significant reinterpretation of the role of local governments, businesses and citizens, which in turn might imply a complex re-organisation of governing. This article will explore what potential roles cities might have in governing the sharing economy. Four Swedish cities serve as case studies for this purpose: Stockholm, Gothenburg, Malmö and Umeå. City data was collected primarily through qualitative means of investigation, including workshops, interviews and desk research. In Malmö, additional participatory observations were conducted on the testbed Sege Park. Results were analysed with a framework developed for understanding the various governing roles for cities in the sharing economy. Three dominant modes of governing were identified and discussed: Governing by provision and authority; governing by partnership and enabling; and governing through volunteering. The four cities made use of all three governing modes, although with a primary focus on governing by authority and governing through partnership. When characterised by governing through volunteering, projects were always initiated by the city, but then run formally by an NGO. While all governing modes may have a role and a purpose in the sharing economy, it is still important that cities reflect upon what are their actual implications. Risks include a collaborative governing mode out-competing some businesses, for example, and a self-governing mode reducing the action space of the volunteer sector.
|
|
| 4. |
|
|
| 5. |
- Svensson, Karolina, 1993-, et al.
(författare)
-
Coupling microchip pressure regulators with chipHPLC as a step toward fully portable analysis system
- 2023
-
Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 385
-
Tidskriftsartikel (refereegranskat)abstract
- Herein the coupling of a miniaturized, nanoliter scaled, pressure regulator (chipPR), and a chipHPLC device is introduced. The active temperature based flow control of the chipPR is able to generate rapid pressure changes and therefore enables on-chip pinched injection and flow gradients with reduced instrumental effort and minimal dead volumes. The functionality of the chipPR empowered chipHLPC device was demonstrated with high-speed HPLC-separations applying fluorescence and electrospray mass spectrometry (ESI-MS) detection. The system shows excellent long-term stability of chromatography integrity (retention times with RSD of 0.44-0.91%) due to the integration of a PID feedback regulation. This first chip-based HPLC device equipped with chipPRs enables precise flow control with significantly reduced technical effort compared to the state-of-the-art.
|
|
| 6. |
- Svensson, Karolina, 1993-, et al.
(författare)
-
High-pressure microfluidic electrochemical and image analysis dual detection for HPLC
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- High-performance liquid chromatography (HPLC) is often set as the lab-based golden standard. For point-of-care and point-of-site applications, making HPLC portable, easy to use and low cost, is very desirable. To reach lower costs, one important task is the development of suitable detectors. Because of the potential for low cost and high performance, a dual-detection microfluidic chip with an electrochemical detector (ECD) and optical access for image analysis was evaluated at high pressure, downstream an HPLC column. For the image analysis, a camera and near-UV-light was used to extract absorption data. To validate the response, a spectrometer was coupled downstream the chip. The results of the three different detectors were comparable, with the camera providing similar absorbance-time chromatograms as the spectrometer. However, the ECD registered only peaks from one of two analytes. To conclude, this experimental setup has potential to provide better understanding of the capability for microfluidic HPLC systems.
|
|
| 7. |
- Svensson, Karolina, 1993-, et al.
(författare)
-
Portable high-pressure pump system for HPLC combining pressurized gas and on-chip pressure regulation
- 2024
-
Ingår i: Sensors and Actuators A-Physical. - : Elsevier. - 0924-4247 .- 1873-3069. ; 371
-
Tidskriftsartikel (refereegranskat)abstract
- High-pressure pumps for microfluidic systems typically require high powerand have large sizes, which hinder portability of otherwise miniaturized HPLC systems. To solve this, a battery-powered, pneumatic system for pressure-driven chromatography is presented. The system utilizes the stored energy in pressurized gas without consuming any of the gas. As the chromatography liquid flows, the gas in the pressure container expands and its pressure reduces. To compensate for this, a solution is presented with an on-chip microfluidic pressure regulator. The chip contains a microfluidic restrictor where fluid is heated by Joule heating to decrease viscosity, and thus reduce the pressure drop over the restrictor. An 18 V battery driven system with 50 ml N2 at 51 bar could provide a water flow rate of 55 µl/min at 32 bar for 67 min with a mean power consumption of 0.2 W. With the regulating microfluidic chip, the pressure stability was 2 mbar, i.e., on pair with high-quality high-pressure syringe pumps. The required gas volume, and hence the total size, is scalable with the desired liquid volume, which makes it suitable for miniaturized systems.
|
|
| 8. |
- Södergren, Karolina, et al.
(författare)
-
How Organization Models Impact the Governing of Industrial Symbiosis in Public Wastewater Management. An Explorative Study in Sweden
- 2021
-
Ingår i: Water. - : MDPI AG. - 2073-4441. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- The industrial symbiosis (IS) landscape is evolving rapidly. While previous studies have argued for the importance of municipalities participating in the governing of IS, research on the implications of different forms of municipal organization is still lacking. This paper aims to investigate how municipal administration and municipally-owned corporations, as two forms of organization, impact the governing of IS in the water and sewage sector. This is explored in relation to the Swedish municipality Simrishamn, which recently underwent changes in the form of organization. Results show that municipal administration contributes to a more inclusive process where many actors can influence and bring ideas and perspectives on how to develop an IS. The risk, however, is that other issues within the municipality are seen as more pressing and, therefore, get prioritized before IS. In corporate form, the development of IS becomes more business-like as the focus is kept on core business. Technology development is strengthened as skills and competencies are promoted through the expertise of the employees. Drawbacks include processes becoming less transparent and political goals, such as citizen welfare not receiving the same level of priority as within municipal administration. There is also a risk that fewer perspectives are included in the process of developing IS, which may inhibit innovation, even if the results also indicate that an increased business focus of the corporate form strengthens the innovation capacity.
|
|
| 9. |
- Södergren, Karolina, et al.
(författare)
-
The role of local governments in overcoming barriers to industrial symbiosis
- 2021
-
Ingår i: Cleaner Environmental Systems. - : Elsevier BV. - 2666-7894. ; 2
-
Tidskriftsartikel (refereegranskat)abstract
- The industrial symbiosis (IS) landscape is evolving at high speed. There is a growing interest in knowledge sharing and partnering, as is evident from the establishment of multiple IS networks at local and regional level. This article investigates the role of local governments in industrial symbiosis. It aims to build a theoretical framework explaining how local governments can reduce barriers to implementation of IS by applying different modes of governing. Findings show that local governments can do many things to overcome barriers and thus enhance IS. In many instances, local governments can support IS in an enabling function, by coordinating relationships and material exchanges, providing infrastructure and funding. They can also apply authoritarian and self-governing principles to develop policies and regulations to support IS development, as well as planning and control mechanisms linked to their own material and resource flows. This article concludes by suggesting a number of policy recommendations, such as local governments establishing a clear strategy on IS, and including IS in physical planning.
|
|
| 10. |
- Södergren, Simon, 1992-, et al.
(författare)
-
In-line small high-pressure sensors in anodically bonded microfluidic restrictors
- 2023
-
Ingår i: Sensors and Actuators A-Physical. - : ELSEVIER SCIENCE SA. - 0924-4247 .- 1873-3069. ; 356
-
Tidskriftsartikel (refereegranskat)abstract
- High-pressure microflow chemistry is advancing due to its potential advantages of being rapid, inexpensive, and accessible. However, as microfluidic devices gain popularity in areas such as synthesis and analysis, there is still a lack of control over thermodynamic parameters during high-pressure processes. This is an effect of existing external sensors causing an excessive increase in the system's internal and dead volumes. To avoid this, more sensors need to be integrated into high-pressure-resistant microfluidic channels. Herein, a proposed approach for integrating an in-line pressure-flow-temperature sensor is provided, where the flow is calculated from the pressure drop over a restrictor. An anodically bonded Si-glass microfluidic chip was constructed with wet-etched glass channels, boron-doped piezoresistors, and dry-etched diaphragms. The pressure sensors showed a precision of +/- 0.07% of full scale (70 bar) and the chip can withstand more than 210 bar. The internal volume was 25 nL and the diaphragms measured 72 x 108 mu m. With this work, improved control of high-pressure microfluidics has been accomplished.
|
|
