Coplanar Electrode Fluidic-Based Acoustic Sensing Method For Underwater Applications
Tesis ini mencadangkan kaedah penderiaan akustik berasaskan cecair untuk aplikasi bawah air. Mekanisme penderiaan yang dipilih adalah berdasarkan konsep kemuatan yang terhasil daripada elektrod koplanar. Struktur tersebut dicadangkan untuk mengatasi beberapa permasalahan yang timbul daripada peranti...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2016
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| Subjects: | |
| Online Access: | http://eprints.usm.my/41001/1/Coplanar_Electrode_Fluidic-Based_Acoustic_Sensing_Method_For_Underwater_Applications.pdf |
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| Summary: | Tesis ini mencadangkan kaedah penderiaan akustik berasaskan cecair untuk aplikasi bawah air. Mekanisme penderiaan yang dipilih adalah berdasarkan konsep kemuatan yang terhasil daripada elektrod koplanar. Struktur tersebut dicadangkan untuk mengatasi beberapa permasalahan yang timbul daripada peranti sediada iaitu Pemuat Mikromesin Transduser Ultrasonik. Isu kebolehbergantungan, disebabkan lengkungan membran yang berlebihan diatasi dengan menyuntik cecair di bawah lapisan membran bagi menambah nilai redaman ketika beroperasi di bawah tekanan luaran dan voltan yang tinggi. Penggunaan teknik litografi lembut untuk fabrikasi memberi kelebihan disebabkan proses yang lebih ringkas. Kaedah penderiaan ini dibuktikan melalui kitaran lengkap yang terdiri daripada proses pemodelan, fabrikasi dan pengujian. Dimensi struktur mematuhi kriteria yang ditetapkan seperti teori lengkungan membran dan teori penembusan kedalaman. Ujian akhir menunjukkan kebolehan peranti untuk mengesan isyarat akustik 200kHz yang dipancarkan melalui peranti bawah air dengan bacaan sensitiviti sebanyak 0.67pF/Pa. Kesan persekitaran seperti getaran pada frekuensi rendah (10Hz to 100Hz) dan perubahan suhu (-20 ̊C to 30 ̊C) juga didapati tidak memberi kesan terhadap operasi peranti. Ini menujukkan kestabilan peranti untuk berfungsi pada keadaan tertentu.
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The thesis proposed a novel fluidic-based acoustic sensing method for underwater applications. The capacitive principles based on coplanar electrodes configuration is selected as the sensing mechanism. The new structure device was proposed to overcome several issues faced by the conventional device based on Capacitive Micromachined Ultrasonic Transducer (CMUT) by adapting the microfluidic technology. Reliability issues caused by the over deflected membrane was overcame by introducing the liquid backing material underneath the membrane which increases the damping at high operating voltage and high external pressure. The use of softlitography technique for fabrication also gave an advantage due to its process simplicity. The sensing concept was proven through a development cycle which consists of modelling, fabricating and testing. The structural design had satisfied several design rules such as membrane deflection theory as well as penetration depth theory. The final testing showed the ability of the device to detect 200kHz acoustic signal transmitted from the underwater acoustic projector with capacitive pressure sensitivity of 0.4 fF/Pa. It was also found that the constant frequency vibration (10Hz to 100Hz) and change of temperature (-20 ̊C to 30 ̊C) has minimal effect on the sensing performance, thus showcased the stability of the sensor.
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