Design and Integration of a Socket, Chamber, and Automated Control System for an E-nose based on CMOS Pixelated Capacitive Sensor array
C.R. Chen (TU Delft - Electrical Engineering, Mathematics and Computer Science)
F. Lin (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Frans Widdershoven – Mentor (TU Delft - Bio-Electronics)
T. Shen – Mentor (TU Delft - Bio-Electronics)
Mohamed A. Basyooni-M.Kabatas – Mentor (TU Delft - Dynamics of Micro and Nano Systems)
C. Verhoeven – Graduation committee member (TU Delft - Electronics)
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Abstract
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.