Micro et nano-patterning de polymères conducteurs pour des applications biomédicales

Bioelectronics uses electrical signals to interact with biological systems. Sensors that allow for electrical read-out of important disease markers, and implants/stimulators used for the detection and treatment of pathological cellular activity are only a few examples of what this technology can offer. Due to their intriguing electroactive and mechanical properties, organic electronics or π-conjugated materials have been extensively explored regarding their use in bioelectronics applications. The attractive mixed electronic/ionic conductivity feature of conducting polymers enables coupling between the electronic charges in the bulk of the organic films with ion fluxes in biological medium. The prototypical material of organic bioelectronics is the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate (PSS). PEDOT:PSS is commercially available, water-dispersible conjugated polymer complex that can be cast into films of high hole and cation conductivity, good charge storage capacity, biocompatibility, and chemical stability. In the present work we investigate an approach to tailor the mechanical, electrical, and electrochemical properties of PEDOT:PSS and study their impact on the performance of organic electrochemical transistors. In addition, we study the effect of micro-structuring and nano-patterning on the electrochemical impedance of PEDOT:PSS- coated gold electrodes for future neural recordings and stimulation. Moreover we demonstrate the use of micro-patterned PEDOT:PSS in cell adhesion and migration.La bioélectronique utilise des signaux électriques pour interagir avec des systèmes biologiques. Les capteurs qui permettent la lecture électrique de marqueurs de maladies importantes et les implants/stimulateurs utilisés pour la détection et le traitement d'activité cellulaire pathologique ne sont que quelques exemples de ce que cette technologie peut offrir. Du fait de leurs propriétés électro-actives et mécaniques fascinantes, l'électronique organique ou les matériaux conjugués π ont été largement exploités dans le domaine de la bioélectronique. Le mélange intéressant entre conductivité électronique et ionique de ces polymères conducteurs permet le couplage entre les charges électroniques présentent dans le volume des films organiques avec les flux ioniques du milieu biologique. Le matériau prototypique de la bioélectronique organique est le polymère conducteur poly(3,4-éthylènedioxythiophène) (PEDOT) dopé avec du polystyrène sulfonate (PSS). Dans ce rapport, nous étudierons une approche pour moduler les propriétés mécaniques, électriques et électrochimiques du PEDOT: PSS et étudier leur impact sur la performance des transistors électrochimiques organiques. Par ailleurs, nous évaluerons l'effet de la micro-structuration et du nano-patterning sur l'impédance électrochimique des électrodes en or recouvertes de PEDOT: PSS utiles pour de futurs enregistrements et stimulations neurales. Enfin, nous démontrerons l'utilisation du PEDOT:PSS à micro-motifs pour l'adhésion et la migration de cellules

Micro- and nano-patterning of conducting polymers for biomedical applications

La bioélectronique utilise des signaux électriques pour interagir avec des systèmes biologiques. Les capteurs qui permettent la lecture électrique de marqueurs de maladies importantes et les implants/stimulateurs utilisés pour la détection et le traitement d'activité cellulaire pathologique ne sont que quelques exemples de ce que cette technologie peut offrir. Du fait de leurs propriétés électro-actives et mécaniques fascinantes, l'électronique organique ou les matériaux conjugués π ont été largement exploités dans le domaine de la bioélectronique. Le mélange intéressant entre conductivité électronique et ionique de ces polymères conducteurs permet le couplage entre les charges électroniques présentent dans le volume des films organiques avec les flux ioniques du milieu biologique. Le matériau prototypique de la bioélectronique organique est le polymère conducteur poly(3,4-éthylènedioxythiophène) (PEDOT) dopé avec du polystyrène sulfonate (PSS). Dans ce rapport, nous étudierons une approche pour moduler les propriétés mécaniques, électriques et électrochimiques du PEDOT: PSS et étudier leur impact sur la performance des transistors électrochimiques organiques. Par ailleurs, nous évaluerons l'effet de la micro-structuration et du nano-patterning sur l'impédance électrochimique des électrodes en or recouvertes de PEDOT: PSS utiles pour de futurs enregistrements et stimulations neurales. Enfin, nous démontrerons l'utilisation du PEDOT:PSS à micro-motifs pour l'adhésion et la migration de cellules.Bioelectronics uses electrical signals to interact with biological systems. Sensors that allow for electrical read-out of important disease markers, and implants/stimulators used for the detection and treatment of pathological cellular activity are only a few examples of what this technology can offer. Due to their intriguing electroactive and mechanical properties, organic electronics or π-conjugated materials have been extensively explored regarding their use in bioelectronics applications. The attractive mixed electronic/ionic conductivity feature of conducting polymers enables coupling between the electronic charges in the bulk of the organic films with ion fluxes in biological medium. The prototypical material of organic bioelectronics is the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate (PSS). PEDOT:PSS is commercially available, water-dispersible conjugated polymer complex that can be cast into films of high hole and cation conductivity, good charge storage capacity, biocompatibility, and chemical stability. In the present work we investigate an approach to tailor the mechanical, electrical, and electrochemical properties of PEDOT:PSS and study their impact on the performance of organic electrochemical transistors. In addition, we study the effect of micro-structuring and nano-patterning on the electrochemical impedance of PEDOT:PSS- coated gold electrodes for future neural recordings and stimulation. Moreover we demonstrate the use of micro-patterned PEDOT:PSS in cell adhesion and migration

The role of absorbed water in ionic liquid cellulosic electrolytes for ionic thermoelectrics

The advantages of large output thermovoltage and sustainable constituent materials have generated a rapid growth in research about ionic thermoelectrics. Recently, giant values of ionic Seebeck coefficients up to 10-26 mV K-1 have been reported. However, the fundamental understanding of the ionic thermoelectric effect is still rudimentary and there is a lack of a well-established measurement standard. In this work, we systematically studied the ionic thermoelectric properties of gel electrolytes made of hydroxyethyl cellulose and an ionic liquid. We discovered that the absorbed water from the atmosphere into the cellulose/ionic liquid gel dramatically increases the apparent ionic Seebeck coefficient from 3 to 12.5 mV K-1. We identified the contribution of a hydrovoltaic voltage generated from water concentration difference as the main reason for the enhanced apparent ionic Seebeck coefficient, which depends on the kinetics of water absorption and desorption on the cold and hot side of the device. Finally, we demonstrated that it is possible to harvest electricity and charge a supercapacitor with intermittent temperature gradients by using this combination of ionic Seebeck voltage and hydrovoltaic voltage.Funding Agencies|Swedish Research Council VRSwedish Research Council [2016-05990, 2018-04037]; Advanced Functional Materials Center at Linkoping University [2009-00971]; Vinnova for the Digital Cellulose Competence Center (DCC)Vinnova [2016-05193]</p

Stretchable Tissue-Like Gold Nanowire Composites with Long-Term Stability for Neural Interfaces.

Publication status: PublishedFunder: Swedish Foundation for Strategic Research; doi: http://dx.doi.org/10.13039/501100001729Soft and stretchable nanocomposites can match the mechanical properties of neural tissue, thereby minimizing foreign body reactions to provide optimal stimulation and recording specificity. Soft materials for neural interfaces should simultaneously fulfill a wide range of requirements, including low Young's modulus (> 1000 S cm-1), biocompatibility, and chronic stability (>> 1 year). Current nanocomposites do not fulfill the above requirements, in particular not the combination of softness and high conductivity. Here, this challenge is addressed by developing a scalable and robust synthesis route based on polymeric reducing agents for smooth, high-aspect ratio gold nanowires (AuNWs) of controllable dimensions with excellent biocompatibility. AuNW-silicone composites show outstanding performance with nerve-like softness (250 kPa), high conductivity (16 000 S cm-1), and reversible stretchability. Soft multielectrode cuffs based on the composite achieve selective functional stimulation, recordings of sensory stimuli in rat sciatic nerves, and show an accelerated lifetime stability of >3 years. The scalable synthesis method provides a chemically stable alternative to the widely used AgNWs, thereby enabling new applications within electronics, biomedical devices, and electrochemistry

Stretchable Tissue-Like Gold Nanowire Composites with Long-Term Stability for Neural Interfaces

Soft and stretchable nanocomposites can match the mechanical properties of neural tissue, thereby minimizing foreign body reactions to provide optimal stimulation and recording specificity. Soft materials for neural interfaces should simultaneously fulfill a wide range of requirements, including low Young’s modulus (&lt;&lt;1 MPa), stretchability (≥30%), high conductivity (&gt;&gt; 1000 S cm−1), biocompatibility, and chronic stability (&gt;&gt; 1 year). Current nanocomposites do not fulfill the above requirements, in particular not the combination of softness and high conductivity. Here, this challenge is addressed by developing a scalable and robust synthesis route based on polymeric reducing agents for smooth, high-aspect ratio gold nanowires (AuNWs) of controllable dimensions with excellent biocompatibility. AuNW-silicone composites show outstanding performance with nerve-like softness (250 kPa), high conductivity (16 000 S cm−1), and reversible stretchability. Soft multielectrode cuffs based on the composite achieve selective functional stimulation, recordings of sensory stimuli in rat sciatic nerves, and show an accelerated lifetime stability of &gt;3 years. The scalable synthesis method provides a chemically stable alternative to the widely used AgNWs, thereby enabling new applications within electronics, biomedical devices, and electrochemistry. This project was financially supported by the Swedish Foundation for Strategic Research, the Swedish Research Council (2019-04424), the Knut and Alice Wallenberg Foundation (Wallenberg Academy Fellow), and the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO Mat LiU No 2009 00971). The authors further acknowledge the Swedish Research Council and Swedish Foundation for Strategic Research for access to ARTEMI, the Swedish National Infrastructure in Advanced Electron Microscopy (2021-00171 and RIF21-0026). M JD would like to acknowledge funding from the European Research Council (834677 “e-NeuroPharma” ERC-2018-ADG). A R acknowledges the funding support from the Marie Skłodowska-Curie Actions Seal of Excellence Fellowship program from the Swedish Governmental Agency for Innovation Systems, VINNOVA (grant 2021-01668). </p