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Identifier

000367442

Title

Συστοιχία ακουστικών βιοαισθητήρων τύπου Lamb για εφαρμογές στην υγεία και στο περιβάλλον

Alternative Title

Lamp-type acoustic biosensors array for applications in health and the environment

Author

Πανταζής, Αλέξανδρος

Thesis advisor

Γκιζέλη, Ηλέκτρα
Κωνσταντινίδης, Γιώργος

Abstract

Acoustic sensors have many applications, ranging from telecommunications to the study of protein interactions. Until now, the majority of the fabricated devices are based on bulk quartz, LiTaO₃ and LiNbO₃, materials that are not compatible with semiconductor processing techniques. Additionally, various parameters, like temperature, affect the operation of the device. As a consequence, the output measurements may have false indications. On the other hand, a great effort is focused on the use of polycrystalline materials, like AlN and ZnO, deposited with the sputtering method. Despite the fact that these materials fulfill the above compatibility, their quality is not the best. This is essential because it can also affect the operation of the device. In this work, a Lamb-wave device was designed for high frequency operation based for the first time on a MOCVD GaN material. MOCVD method is known for producing high quality crystalline layers. The basic target was the development of an acoustic biosensor with high sensitivity to surface perturbations and ability for monolithic integration on the same chip with other sensors and circuits. This is important for lab-on-a-chip applications with wireless data transfer. The fabricated device was evaluated as chemical and biological sensor, demonstrating a high sensitivity. The use of different biomolecules showed the capability to employ the sensor in applications related to health issues and the environment. In the first chapter (Biosensors) the reader will familiarize with the concepts of sensors/ biosensor and their types and characteristics. Second chapter (Acoustic devices) presents a general description of acoustic devices. Emphasis is given on acoustic biosensors, with several examples through bibliography. Lamb and Love type sensors are explained analytically. Chapter three (Materials and methods) contains the various methods and all the materials that were used (from fabrication to biological experiments). In chapter four (Initial experiments) a discussion takes place on the effort to detect bacteria by using Love type biosensors based on quartz material. In fact, the conclusions of this chapter lead to the development of a new system with much improved characteristics. This development, which included the design and fabrication of a Lamb-type sensor based on single-crystalline GaN material, is described in chapter five (Lamb-type acoustic device). The evaluation of the sensor with various chemical and biological molecules is presented in chapter six (Evaluation of Lamb-sensor). Additionally, the temperature effect on its performance is examined, as well as other mechanical parameters. Chapter seven (Multi-frequency experiments) contains the design of Lamb-type devices with different operational frequencies and their evaluation. The goal of this part was to study the sensitivity as a function of frequency. The design and fabrication of a Lamb-type array is described in chapter eight (Lamb-type array sensor). The novelty of the concept was the development of a platform that supports at the same time more than one frequencies, without using an external switch control system. Finally, in chapter nine (Epilogue) all our innovations are discussed. Potential applications of the Lamb-system are presented, while an approximate cost breakdown allows for comparison with commercially available systems.

Language

Greek

Subject

Acoustic device

Biomolecular interactions

Diagnostic Platform

Gallium Nitride

Lab-on-a-chip

Lamb-wave

Semiconductor micromachining

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