Electronic Theses and Dissertation

Biochip berbasis dielektroforesis dengan berbagai konfigurasi mikroelektroda telah cukup banyak diteliti. Namun mikroelektroda umumnya menggunakan bahan yang relatif mahal dan prosedur fabrikasi yang rumit. Penelitian ini bertujuan untuk merancang mikroelektroda konfigurasi oblique dan kemudian digunakan untuk mengetahui karakteristik dielektroforesis (DEP) Lactobacillus casei berdasarkan distribusi medan listrik tidak seragam. Mikroelektroda oblique difabrikasi menggunakan film tembaga di atas substrat kaca dengan teknik transfer pola. Analisis distribusi medan listrik pada mikroelektroda disimulasikan dengan software Quickfield 6.6. Pengujian karakteristik DEP sampel uji Lactobacillus casei dilakukan dengan menerapkan sinyal AC pada mikroelektroda. Sampel uji disiapkan dalam larutan medium dengan konduktivitas listrik 0,05 S/m. Hasil penelitian menunjukkan mikroelektroda konfigurasi oblique dapat difabrikasi menggunakan film tembaga di atas substrat kaca dengan teknik trasfer pola, namun hasilnya tidak terlalu mulus. Simulasi distribusi medan listrik menunjukkan medan paling kuat berada pada daerah spasi elektroda (SE) dan medan paling lemah berada pada daerah spasi ujung elektroda (SUE). Hasil pengujian karakteristik Lactobacillus casei memperlihatkan bahwa hasil nDEP teramati pada frekuensi 60-130 kHz, sedangkan pDEP teramati pada frekuensi 380-700 kHz pada tegangan 2-6 Vpp, dengan gelombang sinusoidal. Fenomena nDEP menyebabkan Lactobacillus casei terdorong menuju medan lemah yaitu daerah spasi ujung elektroda (SUE) dan pDEP menyebabkan Lactobacillus casei tertarik menuju medan kuat yaitu daerah spasi elektroda (SE). Fenomena nDEP dan pDEP kurang teramati dengan sempurna disebabkan mikroelektroda tidak mulus dan ukuran SUE yang cukup besar sehingga medan listrik yang terjadi kurang cukup menghasilkan gaya DEP pada Lactobacillus casei. Secara umum, fenomena DEP terjadi pada mikroelekroda film tembaga konfigurasi oblique.

Kata kunci: Mikroelektroda oblique, Dielektroforesis, Lactobacillus casei, Medan listrik tidak seragam

Dielectrophoresis-based biochips with various microelectrode configurations have been extensively studied. However, microelectrodes generally utilize relatively expensive materials and complicated fabrication procedures. This study aims to design oblique configuration microelectrodes and then use them to determine the dielectrophoretic characteristics (DEP) of Lactobacillus casei based on non-uniform electric field distribution. The oblique microelectrodes were fabricated using a copper film on a glass substrate using a pattern transfer technique. The analysis of electric field distribution on microelectrodes was simulated with Quickfield 6.6 software. Testing the DEP characteristics of the Lactobacillus casei test sample was carried out by applying an AC signal to the microelectrode. The test sample was prepared in a medium solution with an electrical conductivity of 0.05 S/m. The results showed that the oblique configuration microelectrodes can be fabricated using copper film on a glass substrate using pattern transfer techniques, but the results are not very smooth. The electric field distribution simulation shows that the strongest field is in the electrode spacing region (SE) and the weakest field is in the electrode tip spacing (SUE). The results of testing the characteristics of Lactobacillus casei showed that nDEP was observed at a frequency of 60–130 kHz, while pDEP was observed at a frequency of 380–700 kHz at a voltage of 2–6 Vpp with sinusoidal waves. The nDEP phenomenon causes Lactobacillus casei to be pushed towards the weak field, namely the electrode tip space area (SUE) and pDEP causes Lactobacillus casei to be attracted towards the strong field, namely the electrode tip space area (SE). The phenomenon of nDEP and pDEP was not fully observed because the microelectrode was not smooth and the size of SUE was large enough so that the electric field that occurred was not sufficient to produce DEP forces on Lactobacillus casei. In general, the DEP phenomenon occurs on an oblique configuration copper film microelectrodes. Keywords: Oblique microelectroda, Dielectrophoresis, Lactobacillus casei, Non-uniform electric field