Early detection of plant diseases is crucial to minimize crop losses and reduce the usage of pesticides. Electronic Nose (E-Nose) detect volatile organic compounds (VOCs) emitted by stressed or diseased plants, and one such device is a pixelated capacitive sensor (PCS). We designed and built a setup to investigate the influence of light (wavelength and intensity) on the sensitivity of a functionalized PCS for VOCs detection. Our test results indicate that UV illumination, particularly at 375 nm, enhances the sensitivity of the PCS, with a 3-fold enhancement compared to dark conditions. The sensor showed fast saturation (<1 min) and recovery (<2 min) times, confirming the effectiveness of the chamber design for repeatable gas exposure.

This thesis presents the design and implementation of a socket, a chamber and an automated control system for an electronic nose (e-nose) based on CMOS Pixelated Capacitive Sensor (PCS) array chip in a Quad Flat No-Leads (QFN) 5 mm x 5 mm chip package. The objective of this project is to enable repeatable and reliable detection of volatile organic compounds (VOCs) by ensuring a gas-tight sensing environment and minimizing human intervention in experimental procedures, while ensuring good electrical connections by the socket.

A socket was developed to ensure good electrical contact using an anisotropic conductive sheet, allowing the QFN-packaged PCS chip to be inserted and removed without the need for soldering. The socket interfaces with a tightly sealed chamber to prevent gas leakage (< 0.1 ml/min) and maintain a stable gas flow across the sensor. Both components were prototyped in Polyethylene Terephthalate Glycol (PETG) and therefore do not fulfill the final requirement for heat and chemical resistance yet.

To automate gas delivery, the system integrates Bronkhorst mass flow controllers and RVM industrial microfluidic rotary valves. A Python-based graphical user interface (GUI) was developed to schedule gas flow profiles, control valve positions and compute VOC concentrations using the Antoine equation and Dalton's Law of Partial Pressures. This enables dynamic delivery of programmable VOC concentration. Although the automated control system meets most mandatory requirements and all trade-off requirements, some limitations remain. These include unreliable serial communication with the valve during automated operation, even though manual operation through the GUI is executed reliably. This inconsistency is likely caused by timing or firmware-related issues.

With the development of sensor miniaturization and intelligence, the application of flexible electrochemical sensors in health monitoring and drug testing is gradually emerging. The current research focuses on the electrode application of conductive nanomaterials, and carbon-based composites are increasingly widely used in the field of flexible sensors due to their excellent conductivity and flexibility. Among them, boron-doped diamond (BDD) has attracted much attention due to its excellent electrochemical properties and corrosion resistance, making it an ideal electrode material for integration in flexible sensors. The combination of 3D printing technology, especially fused deposition modeling (FDM), provides a new path for flexible electrode manufacturing with high efficiency and low cost.
In this study, we explored the FDM printing performance of TPU/CNT/BDD and TPU/CB composites and their potential as flexible electrodes. The results show that TPU/CNT/BDD printing is difficult and the resistance increases after printing. In contrast, the printing process of TPU/CB material is simple, repeatable, and maintains excellent structural stability and conductivity under mechanical stretching. In electrochemical tests, DMSO treatment can significantly improve the conductivity and redox activity of TPU/CB electrodes, indicating that this strategy has broad prospects for applications such as flexible electronic devices, wearable sensors and energy storage devices.