Tailoring the structure-property of segmented ionenes through analysis of thermomechanical and electrical properties

Ionenes are ion-containing polymers with ions located on the polymer backbone. This characteristic of ionenes can be used to tailor the structure of polymers for a variety of applications. In this dissertation, we have investigated the effects of ionene microstructure on the properties of elastomeric samples. Placement of charge density in segmented ionenes can be controlled through the selection of soft/hard segments, changing the ratio of soft/hard segments, the molecular weight alteration of the soft segment, and microphase separation. The influences of these parameters were investigated through the synthesis of ionenes with various properties, while the structure-property relationships were scrutinized. In the first study, the results from molecular dynamics (MD) simulations of the ionene structure were compared with the experimental tests to evaluate the effect of microphase separation and ionic aggregation of ionene on their properties. The results of this study are discussed in detail in Chapter 3. The second study focused on using poly(ethylene glycol) (PEG) as the soft segment component of segmented block ionenes with two types of aliphatic hard segments (linear aliphatic and DABCO). All PEG samples created crystallized structures, and the highest melting temperature was obtained for PEG50/DD-ionene in both hard segment types, which confirms the effect of phase mixing on limiting the crystallinity in PEG75/DD-ionenes. The results of this study are discussed in detail in Chapter 4. The third study was based on the previous investigated to compare the effect of soft segment type on final properties using PTMO monomer as the soft segment. In this set of samples, the aromatic configuration of the hard segment created a more phase segregated 16 structure, particularly in DABCO-based PTMO25/DD-ionenes. This sample showed a broad rubbery plateau which is related to a high fraction of ionic aggregates and the formation of a stable network. The results of this study are discussed in detail in Chapter 5. In Chapter 6, two molecular weight of PEG soft segment (1000 and 4000 g/mol) were selected to study the effect of spacer length. From XRD results, it was evident that PEG1k/DD-ionenes formed an amorphous morphology and the crystalline structure occurred by increasing the molecular weight of PEG to 4000 g/mol. This significant change in crystalline structure resulted in an obvious difference in mechanical properties. Due to the versatility of the ionene design, a variety of potential applications for well-defined ionenes can be suggested. In Chapter 7, we focused on designing the composite components to change the electrical properties as a function of soft to hard segment ratios of aliphatic ionenes. We integrated carbon nanofibers (CNFs) and modified CNFs to create electrically conductive networks. The sensitivity of ionene composites under strain and recovery of the structure after unloading were selected as effective measures to identify the optimum components of the composite for sensing applications

Transient Electronics as Sustainable Systems: From Fundamentals to Applications

The unique attribute of transient technology is that it promotes the potential for the design and implementation of sustainable systems through their capability to fully or partially disintegrate after a predefined period of stable operation. Transient electronics have a wide range of potential applications as biomedical implants, environmental sensors, and hardware‐secured devices. Controlled disintegration of such systems without the need for harsh solvents is a step toward realizing green and sustainable electronics. In this short review, recent progress in the development of transient electronics is studied. First, an overview of the transient materials, both the substrate and electronic component, is described. Second, the mechanisms under which transiency occurs, including aqueous dissolution and thermal degradation, are reported. Third, manufacturing techniques for the fabrication of transient electronics are reviewed. And last, various transient electronic devices and their applications are discussed.This is the published version of the following article: Jamshidi, Reihaneh, Mehrnoosh Taghavimehr, Yuanfen Chen, Nicole Hashemi, and Reza Montazami. "Transient Electronics as Sustainable Systems: From Fundamentals to Applications." Advanced Sustainable Systems: 2100057. DOI: 10.1002/adsu.202100057. Posted with permission.</p

Microfluidic Seeding of Cells on the Inner Surface of Alginate Hollow Microfibers

Mimicking microvascular tissue microenvironment in vitro calls for a cytocompatible technique of manufacturing biocompatible hollow microfibers suitable for cell-encapsulation/seeding in and around them. The techniques reported to date either have a limit on the microfiber dimensions or undergo a complex manufacturing process. Here, a microfluidic-based method for cell seeding inside alginate hollow microfibers is designed whereby mouse astrocytes (C8-D1A) are passively seeded on the inner surface of these hollow microfibers. Collagen I and poly-d-lysine, as cell attachment additives, are tested to assess cell adhesion and viability; the results are compared with nonadditive-based hollow microfibers (BARE). The BARE furnishes better cell attachment and higher cell viability immediately after manufacturing, and an increasing trend in the cell viability is observed between Day 0 and Day 2. Swelling analysis using percentage initial weight and width is performed on BARE microfibers furnishing a maximum of 124.1% and 106.1%, respectively. Degradation analysis using weight observed a 62% loss after 3 days, with 46% occurring in the first 12 h. In the frequency sweep test performed, the storage modulus (G′) remains comparatively higher than the loss modulus (G″) in the frequency range 0–20 Hz, indicating high elastic behavior of the hollow microfibers.This is the published version of the following article: Aykar, Saurabh S., Nima Alimoradi, Mehrnoosh Taghavimehr, Reza Montazami, and Nicole N. Hashemi. "Microfluidic Seeding of Cells on the Inner Surface of Alginate Hollow Microfibers." Advanced Healthcare Materials: 2102701. DOI: 10.1002/adhm.202102701. Copyright 2022 The Authors. Attribution 4.0 International (CC BY 4.0). Posted with permission

Machine learning-assisted E-jet printing of organic flexible electronics

Electrohydrodynamic-jet (e-jet) printing technique enables the high-resolution printing of complex soft electronic devices. As such, it has an unmatched potential for becoming the conventional technique for printing soft electronic devices. In this study, the electrical conductivity of the e-jet printed circuits was studied as a function of key printing parameters (nozzle speed, ink flow rate, and voltage). The collected experimental dataset was then used to train a machine learning algorithm to establish models capable of predicting the characteristics of the printed circuits in real-time. Decision tree was applied on the data set and resulted in the accuracy of 0.72 and further evaluations showed that pruning the tree increased the accuracy while sensitivity decreased in the highly pruned trees. The k-fold cross validation (CV) method was used in model selection to test the ability of model to get trained on data. The accuracy of CV method was the highest for random forest at 0.83 and K-NN model (k = 10) at 0.82. Precision parameters were compared to evaluate the supervised classification models. According to F-measure values, the K-NN model (k = 10) and random forest are the best methods to classify the conductivity of electrodes.This is a manuscript of an article published as Shirsavar, Mehran Abbasi, Mehrnoosh Taghavimehr, Lionel J. Ouedraogo, Mojan Javaheripi, Nicole N. Hashemi, Farinaz Koushanfar, and Reza Montazami. "Machine learning-assisted E-jet printing of organic flexible electronics." Biosensors and Bioelectronics (2022): 114418. DOI: 10.1016/j.bios.2022.114418. Copyright 2022 Elsevier B.V. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission

Capacitance of Flexible Polymer/Graphene Microstructures with High Mechanical Strength

Carbon-modified fibrous structures with high biocompatibility have attracted much attention due to their low cost, sustainability, abundance, and excellent electrical properties. However, some carbon-based materials possess low specific capacitance and electrochemical performance, which pose significant challenges in developing electronic microdevices. In this study, we report a microfluidic-based technique of manufacturing alginate hollow microfibers incorporated by water dispersed modified graphene (bovine serum albumin–graphene). These architectures successfully exhibited enhanced conductivity ∼20 times higher than alginate hollow microfibers without any significant change in the inner dimension of the hollow region (220.0 ± 10.0 μm) compared with pure alginate hollow microfibers. In the presence of graphene, higher specific surface permeability, active ion adsorption sites, and shorter pathways were created. These continuous ion transport networks resulted in improved electrochemical performance. The desired electrochemical properties of the microfibers make alginate/graphene hollow fibers an excellent choice for further use in the development of flexible capacitors with the potential to be used in smart health electronics.This is a manuscript of an article is published as Nasirian, Vahid, Amir Ehsan Niaraki-Asli, Saurabh S. Aykar, Mehrnoosh Taghavimehr, Reza Montazami, and Nicole N. Hashemi. "Capacitance of Flexible Polymer/Graphene Microstructures with High Mechanical Strength." 3D Printing and Additive Manufacturing (2022). Final publication is available from Mary Ann Liebert, Inc., publishers. http://dx.doi.org/10.1089/3dp.2022.0026 Copyright 2022 Mary Ann Liebert, Inc. Posted with permission

Minute-sensitive real-time monitoring of neural cells through printed graphene microelectrodes

Real-time and high-throughput cytometric monitoring of neural cells exposed to injury mechanisms is invaluable for in-vitro studies. Electrical impedance spectroscopy via microelectrode arrays is a label-free technique for monitoring of neural growth and their detachment upon death. In this method, the interface material plays a vital role to provide desirable attachment cues for the cell network. Thus, here we demonstrate the electrohydrodynamic patterning of aqueous graphene for microelectrode fabrication. We investigated whether the wrinkled surface morphology of the electrodes fabricated by this deposition method expands their electroactive surface area and thus enables a rapid response time. The nano-scale quality of the graphene lattice is characterized by Raman spectroscopy and Transmittance electron microscopy. N27 rat dopaminergic neural cells were cultured on the chips and the surface morphology of the microelectrodes during cellular growth was investigated by Scanning electrode spectroscopy. Attachment of the neural population on the graphene microelectrodes was parametrized and the change in the impedance spectrum of this cell population was quantified at 10 Hz to 10 kHz frequencies along with the change in TUBB3 gene expression. The viability test of the cell population on the biosensor demonstrated no significant difference in comparison to the control, and a cell density of 2289 cell/mm2 was achieved. As a proof of concept, the confluent N27 cell population was exposed to UV and its cytotoxic impact on neural detachment and lift-off was monitored. The multiplexed detection of cellular activity was reported with a temporal resolution of one minute.This is a manuscript of an article published as Niaraki, Amir, Mehran Abbasi Shirsavar, Saurabh S. Aykar, Mehrnoosh Taghavimehr, Reza Montazami, and Nicole N. Hashemi. "Minute-sensitive real-time monitoring of neural cells through printed graphene microelectrodes." 210 Biosensors and Bioelectronics (2022): 114284. DOI: 10.1016/j.bios.2022.114284. Copyright 2022 Elsevier B.V. Attribution 4.0 International (CC BY 4.0) Posted with permission

Polyethylene Glycol Wrapped Alginate/Graphene Hollow Microfibers as Flexible Supercapacitors

Carbon-modified fibrous structures with high biocompatibility have attracted much attention as supercapacitors due to their low cost, sustainability, abundance, and excellent electrochemical performance. However, some of these carbon-based materials suffer from low specific capacitance and electrochemical performance, which have been significant challenges in developing biocompatible electronic devices. In this regard, several studies have been reported on the development of 3D carbon-based micro architectures that provided high conductivity, energy storage potential, and 3D porosity frameworks. This study reports manufacturing of microfluidic Alginate hollow microfiber modified by water-soluble modified Graphene (BSA-Graphene). These architectures successfully exhibited conductivity enhancement conductivity of about 20 times more compared to Alginate hollow microfibers, and without any significant change in the inner-dimension values of hollow region (220.0 ± 10.0 µm) in comparison with pure alginate hollow microfibers. In the presence of Graphene, more obtained specific surface permeability and active ion adsorption sites could successfully provide as shorter pathways. These obtained continuous ion transport networks resulted in improved electrochemical performance. These desired electrochemical properties of the microfibers make Alginate/Graphene hollow fibers an excellent choice for further use in the development of lightweight flexible supercapacitors with scalable potential to be used in intelligent health electronic gadgets.This is a pre-print of the article Nasirian, Vahid, Amir Ehsan Niaraki-Asli, Saurabh Aykar, Mehrnoosh Taghavimehr, Reza Montazami, and Nicole Hashemi. "Polyethylene Glycol Wrapped Alginate/Graphene Hollow Microfibers as Flexible Supercapacitors." (2021). DOI: 10.33774/chemrxiv-2021-11wh5. Copyright 2021 The Author(s). The content is available under CC BY NC ND 4.0 License. Posted with permission

Machine Learning-Assisted E-jet Printing of Organic Flexible Biosensors

Electrohydrodynamic-jet (e-jet) printing technique enables the high-resolution printing of complex soft electronic devices. As such, it has an unmatched potential for becoming the conventional technique for printing soft electronic devices. In this study, the electrical conductivity of the e-jet printed circuits was studied as a function of key printing parameters (nozzle speed, ink flow rate, and voltage). The collected experimental dataset was then used to train a machine learning algorithm to establish models capable of predicting the characteristics of the printed circuits in real-time. Precision parameters were compared to evaluate the supervised classification models. Since decision tree methods could not increase the accuracy higher than 71%, more advanced algorithms are performed on our dataset to improve the precision of model. According to F-measure values, the K-NN model (k=10) and random forest are the best methods to classify the conductivity of electrodes. The highest accuracy of AdaBoost ensemble learning has resulted in the range of 10-15 trees (87%).This is a pre-print of the article Shirsavar, Mehran Abbasi, Mehrnoosh Taghavimehr, Lionel J. Ouedraogo, Mojan Javaheripi, Nicole N. Hashemi, Farinaz Koushanfar, and Reza Montazami. "Machine Learning-Assisted E-jet Printing of Organic Flexible Biosensors." arXiv preprint arXiv:2111.03985 (2021). Copyright 2021 The Author(s). Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission

Machine Learning-Assisted E-jet Printing of Organic Flexible Biosensors

Electrohydrodynamic-jet (e-jet) printing technique enables the high-resolution printing of complex soft electronic devices. As such, it has an unmatched potential for becoming the conventional technique for printing soft electronic devices. In this study, the electrical conductivity of the e-jet printed circuits was studied as a function of key printing parameters (nozzle speed, ink flow rate, and voltage). The collected experimental dataset was then used to train a machine learning algorithm to establish models capable of predicting the characteristics of the printed circuits in real-time. Precision parameters were compared to evaluate the supervised classification models. Since decision tree methods could not increase the accuracy higher than 71%, more advanced algorithms are performed on our dataset to improve the precision of model. According to F-measure values, the K-NN model (k=10) and random forest are the best methods to classify the conductivity of electrodes. The highest accuracy of AdaBoost ensemble learning has resulted in the range of 10-15 trees (87%).This is a pre-print of the article Shirsavar, Mehran Abbasi, Mehrnoosh Taghavimehr, Lionel J. Ouedraogo, Mojan Javaheripi, Nicole N. Hashemi, Farinaz Koushanfar, and Reza Montazami. "Machine Learning-Assisted E-jet Printing of Organic Flexible Biosensors." arXiv preprint arXiv:2111.03985 (2021). Copyright 2021 The Author(s). Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission

Transient Electronics as Sustainable Systems: From Fundamentals to Applications

The unique attribute of transient technology is that it promotes the potential for the design and implementation of sustainable systems through their capability to fully or partially disintegrate after a predefined period of stable operation. Transient electronics have a wide range of potential applications as biomedical implants, environmental sensors, and hardware-secured devices. Controlled disintegration of such systems without the need for harsh solvents is a step toward realizing green and sustainable electronics. In this short review, recent progress in the development of transient electronics is studied. First, an overview of the transient materials, both the substrate and electronic component, is described. Second, the mechanisms under which transiency occurs, including aqueous dissolution and thermal degradation, are reported. Third, manufacturing techniques for the fabrication of transient electronics are reviewed. And last, various transient electronic devices and their applications are discussed.This is the peer-reviewed version of the following article: Jamshidi, Reihaneh, Mehrnoosh Taghavimehr, Yuanfen Chen, Nicole Hashemi, and Reza Montazami. "Transient Electronics as Sustainable Systems: From Fundamentals to Applications." Advanced Sustainable Systems 6, no. 2 (2022): 2100057, which has been published in final form at DOI: 10.1002/adsu.202100057. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Copyright 2021 The Authors. Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). Posted with permission.