Design and characterization of high-frequency ultrasound microprobe
| Autor: | Kabaši, Anton |
|---|---|
| Přispěvatelé: | Bilušić, Ante, Kovačić, Damir, Krce, Lucija |
| Jazyk: | chorvatština |
| Rok vydání: | 2018 |
| Předmět: | |
| Popis: | Prikazan je cjelokupni proces izrade piezoelektričnih mikroproba koji je izveden na Prirodoslovnomatematičkom fakultetu u Splitu u sklopu nastavka provedbe projekta MEMSplit. Kao uzorak je korišten debeli film PMN-PT (Pb (Mg1/3Nb2/3)O3-PbTiO3). Uzorci su sintetizirani tehnikom sol-gel na Institutu Jožefa Stefana u Ljubljani. Strukturna analiza rendgenskom difrakcijom pokazuje uzorke 30 µm debelog filma PMN-PT-a visoke kvalitete. Mjerenje pretražnim elektronskim mikroskopom pokazuje zrnatu strukturu i poroznost filma s dimenzijama zrna 5 µm. Električna analiza potvrđuje uspješnost polarizacije uzorka. Krivulja električne histereze je dobivena mjerenjem krugom Sawyer-Tower. Određena je rezonantna frekvencija piezoelektrika 28.5 MHz. Istražene su mogućnosti izrade mikroproba metodama optičke litografije za dva različita koncepta fotolitografske maske. Prvi koncept obuhvaća mikroprobu sa linearnim zasjecima piezoelektrika i odbačen je zbog nemogućnosti neizotropnog jetkanja debelog filma PMN-PT-a. Drugi koncept ne uključuje proces jetkanja piezoelektrika. Polariziran je pravokutni dio piezoelektričnog filma i elektrode su nanešene na polarizirani sloj. Optičkom litografijom i procesima podizanja žrtvenog sloja te kemijskim jetkanjem uzorak je pripremljen, polariziran i na njega su nanesene mikrostrukture elektroda za pobuđivanje akustičnog signala. Zbog poroznosti filma i zadržavanja kemikalija korištenih u procesu izrade, došlo je do pucanja nekih elektroda za pobuđivanje akustičnog signala što je privremeno onemogućilo daljnju analizu uzorka. Sljedeći korak bi bio ispitivanje interferencije između ultrazvučnih elemenata te mjerenje akustičkih svojstava mikroproba. We present the entire process of developing a piezoelectric microprobe which was derived at the University of Split,Faculty of Science as a continuation of the MEM Split project. PMN-PT(Pb(Mg1/3Nb2/3)O3PbTiO3) thick film was used as a sample. The samples were synthesized by the sol-gel technique at the Institute Jožef Stefan Ljubljana, Slovenia. Structural analysis by X-ray diffraction has shown a high sample quality with thicknesses of 30 µm. Measurements with a scanning electron microscope have shown a grainy structure and porosity of the films with grain sizes around 5 µm. Electrical analysis confirmed the success of polarisation of the sample. Hysteresis curve was measured using a Sawyer-Tower circuit. The resonant frequency of the piezoelectric was measured at 28.5 MHz. Possibilities of developing a microprobe using methods of photolithography were investigated for two different concepts of the photomask. One concept was a microprobe with a linear kerfed array of piezoelectric elements and was rejected due to the inability of anisotropic chemical etching of PMN-PT. The second concept does not involve etching of the thick film. A rectangular area of the piezoelectric was polarised and electrodes were microstructured on top of it. Using photolithographic processes of lift-off and chemical etching the sample was prepared, polarised and electrodes for exciting the acoustic signal were microstructured on top. Due to the porosity of the film and contamination by chemicals used during the process, some electrodes cracked, which temporarily stopped further analysis. The next step would be to analyse the interference between the ultrasound elements and measurement of the acoustic properties of the microprobes. |
| Databáze: | OpenAIRE |
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