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- Arbring Sjöström, Theresia, 1987-
(författare)
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Organic Bioelectronics for Neurotransmitter Release at the Speed of Life
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The signaling dynamics in neuronal networks includes processes ranging from lifelong neuromodulation to direct synaptic neurotransmission. In chemical synapses, the time delay it takes to pass a signal from one neuron to the next lasts for less than a millisecond. At the post-synaptic neuron, further signaling is either up- or down-regulated, dependent on the specific neurotransmitter and receptor. While this up- and down-regulation of signals usually runs perfectly well and enables complex performance, even a minor dysfunction of this signaling system can cause major complications, in the shape of neurological disorders. The field of organic bioelectronics has the ability to interface neurons with high spatiotemporal recording and stimulation techniques. Local chemical stimulation, i.e. local release of neurotransmitters, enables the possibility of artificially altering the chemical environment in dysfunctional signaling pathways to regain or restore neural function. To successfully interface the biological nervous system with electronics, a range of demands must be met. Organic bioelectronic techniques and materials are capable of reaching the demands on the biological as well as the electronic side of the interface. These demands span from high performance biocompatible materials, to miniaturized and specific device architectures, and high dose control on demand within milliseconds.The content of this thesis is a continuation of the development of organic bioelectronic devices for neurotransmitter delivery. Organic materials are utilized to electrically control the dose of charged neurotransmitters by translating electric charge into controlled artificial release. The first part of the thesis, Papers 1 and 2, includes further development of the resistor-type release device called the organic electronic ion pump. This part includes material evaluation, microfluidic incorporation, and device design considerations. The aim for the second part of this thesis, Papers 3 and 4, is to enhance temporal performance, i.e. reduce the delay between electrical signal and neurotransmitter delivery to corresponding delay in biological neural signaling, while retaining tight dosage control. Diffusion of neurotransmitters between nerve cells is a slow process, but since it is restricted to short distances, the total time delay is short. In our organic bioelectronic devices, several orders of magnitude in speed can be gained by switching from lateral to vertical delivery geometries. This is realized by two different types of vertical diodes combined with a lateral preload and waste configuration. The vertical diode assembly was further expanded with a control electrode that enables individual addressing in each of several combined release sites. These integrated circuits allow for release of neurotransmitters with high on/off release ratios, approaching delivery times on par with biological neurotransmission.
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| 2. |
- Nissa, Josefin, 1987-
(författare)
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Interacting with biological membranes using organic electronic devices
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many physiological processes are reliant on activities in the cell membrane. These activities are of great importance to our well-being since they allow the cells to respond to their environment and communicate with each other to function as tissues and organs. In this thesis the use of organic electronic devices to interface with cell membranes has been explored. Organic electronics are especially suited for the task given their ability to transduce ionic to electronic signals. Four scientific papers are included in the thesis, where organic electronic devices are used together with living cells and supported lipid bilayers (SLB). In the first paper a ferroelectric cell release surface is presented. Release of cells cultured on the surface was induced by a polarization change in the ferroelectric polymer. This non-enzymatic release method was developed primarily for treatment of severe burns.The remaining three papers strive to combine lipid bilayers and the conjugated polymer poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) in biosensors. The target device is an organic electrochemical transistor (OECT) functionalized with a supported lipid bilayer. Several aspects of the integration are explored, including promotion of vesicle fusion onto PEDOT:PSS and optimization of OECT design and biasing conditions for sensing. For SLB formation on PEDOT:PSS two different silica material systems, one PEDOT:PSS/silica composite and one mesoporous silica film, were evaluated with respect to electrical properties and quality of the resulting bilayer. The electrical properties were found to be similar, but the quality of the bilayer was better on the mesoporous silica film.In the last two papers the focus is on optimization of OECTs for sensing purposes. Biasing conditions for operation at high transconductance were identified, as well as design principles for large sensor output in impedance sensing.
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| 3. |
- Seitanidou, Maria, 1985-
(författare)
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Overcoming Limitations of Iontronic Delivery Devices
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organic electronic devices are considered as one of the best candidates to replace conventional inorganic electronic devices due to their electronic conductive functionality, low-cost production techniques, the ability to tune their optical and electronic properties using organic chemistry, and their mechanical flexibility. Moreover, these systems are ideal for bioelectronic applications due to their softness, biocompatibility, and most importantly, their electronic and ionic transport. Indeed, these materials are compatible with biological tissues and cells improving the signal transduction between electronic devices and electrically excitable cells. As ions serve as one of the primary signal carriers of cells, they can selectively tune a cell’s activity; therefore, an improved interface between electronics and biological systems can offer several advantages in healthcare, e.g. the development of efficient drug delivery devices. The main focus of this thesis is the development of electronic delivery devices. Electrophoretic delivery devices called organic electronic ion pumps (OEIPs) are used to electronically control the delivery of small ions, neurotransmitters, and drugs with high spatiotemporal resolution. This work elucidates the ion transport processes and phenomena that happen in the ion exchange membranes during ion delivery and clarifies which parameters are crucial for the ion transport efficiency of the OEIPs. This thesis shows a systematic investigation of these parameters and indicates new methods and OEIP designs to overcome these challenges. Two novel OEIP designs are developed and introduced in this thesis to improve the local ion transport while limiting side effects. OEIPs based on palladium proton trap contacts can improve the membrane permselectivity and optimize the delivery of γ-aminobutyric acid (GABA) neurotransmitters at low pH while preventing any undesired pH changes from proton transport in the biological systems. And OEIPs based on glass capillary fibers are developed to overcome the limitations of devices on planar substrates, related to more complex and larger biologically relevant ion delivery with low mobility for implantable applications. This design can optimize the transport of ions and drugs such as salicylic acid (SA) at low concentrations and at relatively much higher rates, thereby addressing a wider range of biomedically relevant applications and needs.
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| 4. |
- Ajjan, Fátima, 1986-, et al.
(författare)
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Doped Conjugated Polymer Enclosing a Redox Polymer : Wiring Polyquinones with Poly(3,4‐Ethylenedioxythiophene)
- 2020
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Ingår i: Advanced Energy and Sustainability Research. - : John Wiley & Sons. - 2699-9412. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- The mass implementation of renewable energies is limited by the absence of efficient and affordable technology to store electrical energy. Thus, the development of new materials is needed to improve the performance of actual devices such as batteries or supercapacitors. Herein, the facile consecutive chemically oxidative polymerization of poly(1-amino-5-chloroanthraquinone) (PACA) and poly(3,4-ethylenedioxythiophene (PEDOT) resulting in a water dispersible material PACA-PEDOT is shown. The water-based slurry made of PACA-PEDOT nanoparticles can be processed as film coated in ambient atmosphere, a critical feature for scaling up the electrode manufacturing. The novel redox polymer electrode is a nanocomposite that withstands rapid charging (16 A g−1) and delivers high power (5000 W kg−1). At lower current density its storage capacity is high (198 mAh g−1) and displays improved cycling stability (60% after 5000 cycles). Its great electrochemical performance results from the combination of the redox reversibility of the quinone groups in PACA that allows a high amount of charge storage via Faradaic reactions and the high electronic conductivity of PEDOT to access to the redox-active sites. These promising results demonstrate the potential of PACA-PEDOT to make easily organic electrodes from a water-coating process, without toxic metals, and operating in non-flammable aqueous electrolyte for large scale pseudocapacitors.
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