Fully Integrated Biochip Platforms for Advanced Healthcare

Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications

Development of a novel intracortical electrode for chronic neural recordings

PhD ThesisMicromotion, attributable to the modulus mismatch between the brain and electrode materials, is a fundamental phenomenon contributing to electrode failure for invasive Brain-Machine Interfaces. Spike recording quality from conventional chronic electrode designs deteriorates over the weeks/months post-implantation, in terms of signal amplitude and single unit stability, due to glial cell activation by sustained mechanical trauma. Conventional electrode designs consist of a rigid straight shaft and sharp tip, which can augment mechanical trauma sustained due to micromotion. The sinusoidal probe has been fabricated to reduce micromotion related mechanical trauma. The electrode is microfabricated from flexible materials and has design measures such as a sinusoidal shaft, spheroid tip and a 3D polyimide ball anchor to restrict electrode movement relative to the surrounding brain tissue, thus theoretically minimising micromotion. The electrode was compared to standard microwire electrodes and was shown to have more stable chronic recordings in terms of SNR and LFP power. A longer chronic recording period was achieved with the sinusoidal probe for the first generation. Quantitative histology detecting microglia and astrocytes showed reduced neuronal tissue damage especially for the tip region between 6-24 months chronic indwelling period for the sinusoidal probe. This may be linked to the more stable chronic recordings. This is the first demonstration that electrode designs wholly incorporating micromotion- reducing measures may decrease the magnitude of gliosis, with possible chronic recording longevity enhancement