In the emerging research field of bioelectronic medicine, it has been indicated that neuromodulation of the Vagus Nerve (VN) has the potential to treat various conditions such as epilepsy, depression, and autoimmune diseases. In order to reduce side effects, as well as to increase the effectiveness of the delivered therapy, sub-fascicle stimulation specificity is required. In the electrical domain, increasing spatial selectivity can only be achieved using invasive and potentially damaging approaches like compressive forces or nerve penetration. To avoid these invasive methods, while obtaining a high spatial selectivity, a 2 mm diameter extraneural cuff-shaped proof-of-concept design with integrated Lead Zirconate Titanate (PZT) piezoelectric ultrasound transducers is proposed. For the development of the proposed concept, wafer-level microfabrication techniques are employed. Moreover, acoustic measurements are performed on the device, in order to characterize the ultrasonic beam profiles of the integrated PZT-based piezoelectric ultrasound transducers. A focal spot size of 200 μm by 200 μm is measured for the proposed cuff. Moreover, the curvature of the device leads to constructive interference of the ultrasound waves originating from multiple piezoelectric ultrasound transducers, which in turn leads to an increase of 45% in focal pressure compared to the focal pressure of a single piezoelectric ultrasound transducer. Integrating piezoelectric ultrasound transducers in an extraneural cuff-shaped design has the potential to achieve high-precision ultrasound neuromodulation of the Vagus Nerve without requiring intraneural implantation.

This document reports details the development of a solid stool detection system. On behalf of Momo Medical - a TU Delft-based startup company - a device for detecting defecates by elderly people has been designed. The goal of the detection system is to detect solid stools by elderly patients wearing a diaper and to notify the nurses in a nursing home accordingly. The project has been organized and conducted in two groups: Hardware & Software. Our group has been in charge of the hardware. The other group has been responsible for the software. The main focus in this report will be the hardware design of the system. This report contains: the analysis of the problem, the development of a solution, the design and the evaluation of the device in test. The developed device detects methane by means of multiple gas sensors, since methane is the main gas component released while defecating. Several iterations making a suited printed circuit board and case have been carried out, while taking aspects like safety, reliability and noise performance into account. The report concludes with a summary of main results and an outline of future work.