| 1. |
- Benselfelt, Tobias, et al.
(författare)
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Electrochemically Controlled Hydrogels with Electrotunable Permeability and Uniaxial Actuation
- 2023
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 35:45
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Tidskriftsartikel (refereegranskat)abstract
- The unique properties of hydrogels enable the design of life-like soft intelligent systems. However, stimuli-responsive hydrogels still suffer from limited actuation control. Direct electronic control of electronically conductive hydrogels can solve this challenge and allow direct integration with modern electronic systems. An electrochemically controlled nanowire composite hydrogel with high in-plane conductivity that stimulates a uniaxial electrochemical osmotic expansion is demonstrated. This materials system allows precisely controlled shape-morphing at only -1 V, where capacitive charging of the hydrogel bulk leads to a large uniaxial expansion of up to 300%, caused by the ingress of & AP;700 water molecules per electron-ion pair. The material retains its state when turned off, which is ideal for electrotunable membranes as the inherent coupling between the expansion and mesoporosity enables electronic control of permeability for adaptive separation, fractionation, and distribution. Used as electrochemical osmotic hydrogel actuators, they achieve an electroactive pressure of up to 0.7 MPa (1.4 MPa vs dry) and a work density of & AP;150 kJ m-3 (2 MJ m-3 vs dry). This new materials system paves the way to integrate actuation, sensing, and controlled permeation into advanced soft intelligent systems. The unique properties of hydrogels enable the design of life-like soft intelligent systems. This work demonstrates how the swelling of hydrogels from cellulose nanofibrils and carbon nanotubes can be electrochemically controlled to achieve electrochemical osmotic actuation. This new materials system paves the way for integrated actuation, sensing, and controlled permeation in electrotunable separation membranes or soft actuators.image
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| 2. |
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| 3. |
- Piper, Andrew, et al.
(författare)
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A disposable, wearable, flexible, stitched textile electrochemical biosensing platform
- 2021
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Ingår i: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 194
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Tidskriftsartikel (refereegranskat)abstract
- Wearable sensors are a fast growing and exciting research area, the success of smart watches are a great example of the utility and demand for wearable sensing systems. The current state of the art routinely uses expensive and bulky equipment designed for long term use. There is a need for cheap and disposable wearable sensors to make single use measurements, primarily in the area of biomarker detection. Herein we report the ability to make cheap (0.22 USD/sensor), disposable, wearable sensors by stitching conductive gold coated threads into fabrics. These threads are easily functionalised with thiolate self-assembled monolayers which can be designed for the detection of a broad range of different biomarkers. This all textile sensing platform is ideally suited to be scaled up and has the added advantage of being stretchable with insignificant effect on the electrochemistry of the devices. As a proof of principle, the devices have been functionalised with a continuous glucose sensing system which was able to detect glucose in human sweat across the clinically relevant range (0.1-0.6 mM). The sensors have a sensitivity of 126 +/- 14 nA/mM of glucose and a limit of detection of 301 +/- 2 nM. This makes them ideally suited for biomarker detection in point-of-care sensing applications.
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| 4. |
- Shakya, Jyoti, et al.
(författare)
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2D MXene electrochemical transistors
- 2024
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Ingår i: Nanoscale. - 2040-3364 .- 2040-3372. ; 16:6, s. 2883-2893
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Tidskriftsartikel (refereegranskat)abstract
- The solid-state field-effect transistor, FET, and its theories were paramount in the discovery and studies of graphene. In the past two decades another transistor based on conducting polymers, called organic electrochemical transistor (ECT), has been developed and largely studied. The main difference between organic ECTs and FETs is the mode and extent of channel doping; while in FETs the channel only has surface doping through dipoles, the mixed ionic-electronic conductivity of the channel material in organic ECTs enables bulk electrochemical doping. As a result, organic ECTs maximize conductance modulation at the expense of speed. To date ECTs have been based on conducting polymers, but here we show that MXenes, a class of 2D materials beyond graphene, enable the realization of electrochemical transistors (ECTs). We show that the formulas for organic ECTs can be applied to these 2D ECTs and used to extract parameters like mobility. These MXene ECTs have high transconductance values but low on-off ratios. We further show that conductance switching data measured using ECT, in combination with other in situ-ex situ electrochemical measurements, is a powerful tool for correlating the change in conductance to that of the redox state, to our knowledge, this is the first report of this important correlation for MXene films. 2D ECTs can draw great inspiration and theoretical tools from the field of organic ECTs and have the potential to considerably extend the capabilities of transistors beyond those of conducting polymer ECTs, with added properties such as extreme heat resistance, tolerance for solvents, and higher conductivity for both electrons and ions than conducting polymers. Here we show that not only conducting polymers, but also 2D MXenes can be used as materials for electrochemical transistors ECTs. MXene extend the capabilities of ECTs with properties such as extreme heat resistance, and higher conductivity/speeds.
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| 5. |
- Wang, Zhen, et al.
(författare)
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Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium-Ion Batteries
- 2023
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 33:30
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Tidskriftsartikel (refereegranskat)abstract
- Tunable dynamic networks of cellulose nanofibrils (CNFs) are utilized to prepare high-performance polymer gel electrolytes. By swelling an anisotropically dewatered, but never dried, CNF gel in acidic salt solutions, a highly sparse network is constructed with a fraction of CNFs as low as 0.9%, taking advantage of the very high aspect ratio and the ultra-thin thickness of the CNFs (micrometers long and 2–4 nm thick). These CNF networks expose high interfacial areas and can accommodate massive amounts of the ionic conductive liquid polyethylene glycol-based electrolyte into strong homogeneous gel electrolytes. In addition to the reinforced mechanical properties, the presence of the CNFs simultaneously enhances the ionic conductivity due to their excellent strong water-binding capacity according to computational simulations. This strategy renders the electrolyte a room-temperature ionic conductivity of 0.61 ± 0.12 mS cm−1 which is one of the highest among polymer gel electrolytes. The electrolyte shows superior performances as a separator for lithium iron phosphate half-cells in high specific capacity (161 mAh g−1 at 0.1C), excellent rate capability (5C), and cycling stability (94% capacity retention after 300 cycles at 1C) at 60 °C, as well as stable room temperature cycling performance and considerably improved safety compared with commercial liquid electrolyte systems.
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| 6. |
- Wang, Zhen, et al.
(författare)
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Layer-by-Layer Assembly of Strong Thin Films with High Lithium Ion Conductance for Batteries and Beyond
- 2021
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 17:32, s. 2100954-
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Tidskriftsartikel (refereegranskat)abstract
- Polyethylene oxide (PEO) is one of the most widely used polymeric ion conductors which has the potential for a wide range of applications in energy storage. The enhancement of ionic conductivity of PEO-based electrolytes is generally achieved by sacrificing the mechanical properties. Using layer-by-layer (LbL) self-assembly with a nanoscale precision, mechanically strong and self-healable PEO/polyacrylic acid composite thin films with a high Li+ conductivity of 2.3 ± 0.8 × 10−4 S cm−1 at 30 °C, and a strength of 3.7 MPa is prepared. These values make the LbL composite among the best recorded multifunctional solid electrolytes. The electrolyte thin film withstands at least 1000 cycles of striping/plating of Li at 0.05 mA cm−2. It is further shown that the LbL thin films can be used as separators for Li-ion batteries to deliver a capacity of 116 mAh g−1 at 0.1 C in an all-LbL-assembled lithium iron phosphate/lithium titanate battery. Finally, it is demonstrated that the thin films can be used as ion-conducting substrates for flexible electrochemical devices, including micro supercapacitors and electrochemical transistors.
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| 7. |
- Zeglio, Erica, 1987-, et al.
(författare)
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Mixing Insulating Commodity Polymers with Semiconducting n-type Polymers Enables High-Performance Electrochemical Transistors
- 2024
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Ingår i: Advanced Materials. - 0935-9648 .- 1521-4095.
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Tidskriftsartikel (refereegranskat)abstract
- Diluting organic semiconductors with a host insulating polymer is used to increase the electronic mobility in organic electronic devices, such as thin film transistors, while considerably reducing material costs. In contrast to organic electronics, bioelectronic devices such as the organic electrochemical transistor (OECT) rely on both electronic and ionic mobility for efficient operation, making it challenging to integrate hydrophobic polymers as the predominant blend component. This work shows that diluting the n-type conjugated polymer p(N-T) with high molecular weight polystyrene (10 KDa) leads to OECTs with over three times better mobility-volumetric capacitance product (µC*) with respect to the pristine p(N-T) (from 4.3 to 13.4 F V−1 cm−1 s−1) while drastically decreasing the amount of conjugated polymer (six times less). This improvement in µC* is due to a dramatic increase in electronic mobility by two orders of magnitude, from 0.059 to 1.3 cm2 V−1 s−1 for p(N-T):Polystyrene 10 KDa 1:6. Moreover, devices made with this polymer blend show better stability, retaining 77% of the initial drain current after 60 minutes operation in contrast to 12% for pristine p(N-T). These results open a new generation of low-cost organic mixed ionic-electronic conductors where the bulk of the film is made by a commodity polymer.
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