Modelli Elettrochimici di Performance e Rumore per Biosensori e Bioattuatori elettronici

Biosensors and bioactuators are receiving increasing attention and are subject of intense research and development within the general framework of the Internet of Medical Things (IoMT) and Precision Medicine (PM), where the number of portable and connected medical devices is estimated to grow exponentially. Indeed, the benefits envisioned in the IoMT and PM scenarios cannot be achieved with the current technology and huge efforts are needed towards the development of low-cost, low-power, portable and connected, highly sensitive, selective and reliable (bio)sensors and (bio)actuators. Micro and nano-electronics fabrication technology is instrumental to embrace this process and for this reason the field of bioelectronics is blooming. In addition, new materials and, at the biomolecular level, new sensing strategies are investigated and proposed in a large number of papers addressing a growing number of targets. Several new branches have started to catch on, and, despite promising experimental evidence, the poor understanding of the underlying physics and chemistry hampers any systematic device optimization. Here is where modeling and simulation comes to help. This thesis aims to contribute to this general objective by providing several new models and model extensions for bio-chemical sensors and ionic actuators. The research activity contained in this thesis addresses biosensors and ionic actuators using a common theoretical framework that provides insights and presents tools for simulation and optimization of device designs: the main focus is on the modeling of potentiometric biochemical sensors used for monitoring physiological parameters, a class of devices amenable to micro-electronic fabrication and large scale integration. Thus, we study in detail ion interactions with solid surfaces and ion transfer processes at the interfaces between electrolyte and polymeric membranes. Our results shed light on the sensitivity, cross-sensitivity and selectivity of in ion-sensitive field effect transistors. In particular, as concerns sensing surfaces, we present a new and general approach to calculate the power spectral density (PSD) of the surface charge fluctuations, also known as chemical noise, in a straightforward manner. In addition, since polymer-based materials are highly versatile and can be used both for sensing and actuation, we report the development of a time-dependent model capable to capture ion processes supporting membrane and iontronic device development by with a two-fold objective: improving ion-selective membranes models for biosensors and studying transient effects on the ion delivery doses in bioactuators. Although presented here in their 1D form, all models in this thesis are amenable to implementation in more physical dimensions and can be unified in a common general framework model. Our work aims to pave the way to the development of comprehensive models including both the semiconductor and electrolytes/polymeric materials physics, suitable to the support the development and optimization of biosensors and bioactuators. Research activities reported in this thesis have been stimulated and supported by the Italian MIUR and Flag-ERA through the project CONVERGENCE and the European Union's Horizon 2020 research and innovation program under the IN-FET (Ionic Neuromodulation For Epilepsy Treatment) project.