Approaching the Intrinsic Limits of Short Channel Vertical Organic Electrochemical Transistors.

Vertical architectures for organic electrochemical transistors (OECTs), due to their submicrometer channel lengths, have presented themselves as a straightforward design approach for achieving high /τ ratios, a figure of merit that assesses the performance of the devices by virtue of their transconductance ( = d/d) and switching time constant (τ). However, as the practical limitations of the geometries are overcome, the influence of parasitic phenomena becomes more dominant and limits the performance of the device. One approach to reduce the detrimental effects of parasitic resistance in the drain-source circuit is to use a four-point sourcing technique.

Unidirectional Electron-Tunnelling Flexible PDMS Strain Sensor with Aligned Carbon Nanotubes.

High-aspect-ratio carbon nanotubes can be directly mixed into polymers to create piezoresistive polymers. Reducing the cross-sensitivity and creating unidirectional sensitive sensors can be achieved by aligning the nanotubes before they are cured in the polymer layer. This research presents and characterises this alignment of carbon nanotubes inside polydimethylsiloxane and gives the corresponding strain sensor results.

Understanding Electrical Failure of Polyimide-Based Flexible Neural Implants: The Role of Thin Film Adhesion.

The lack of long-term stability of polymeric neural interfaces remains one of the most important and less tackled issues in this research field. To address this issue, we fabricated two test structures based on interdigitated electrodes (IDEs) encapsulated with polyimide (PI). One of the test samples was pretreated with barrel oxygen plasma prior to spin coating of the second PI layer.

Towards Long-Term Stable Polyimide-Based Flexible Electrical Insulation for Chronically Implanted Neural Electrodes.

For chronic applications of flexible neural implants, e.g., intracortical probes, the flexible substrate material has to encapsulate the electrical conductors with a long-term stability against the saline environment of the neural tissue.

An Assessment of Surface Treatments for Adhesion of Polyimide Thin Films.

Polyimide films are currently of great interest for the development of flexible electronics and sensors. In order to ensure a proper integration with other materials and PI itself, some sort of surface modification is required. In this work, microwave oxygen plasma, reactive ion etching oxygen plasma, combination of KOH and HCl solutions, and polyethylenimine solution were used as surface treatments of PI films.