This paper investigates the ability of biomachined lab-on-a-chip (LoC) to perform drug testing of Amphotericin B to the Candida albicans. The chip is made of polydimethyl siloxane (PDMS). Molds are patterned using CNC milling followed by biomachining. CNC milling process creates channel features on the bottom mold, while biomachining forms rough surface on the channels. After the molds are created, LoC can be manufactured using those molds. Hence, contour surface on LoC’s channels is also realized following the mold surface. Later, Candida albicans is seeded on the LoC’s channels for 24 and 48 hours with the continuous flow of Yeast Nitrogen Base (YNB) Sterile. Then, cell viability is tested using 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium (MTT).The result shows that C. albicans could adhere and grow in the LoC channels. Based on this result, drug testing is conducted in the presence and absence of Amphotericin B (Amp B) under two schemes: without (static) and with (dynamic) the continuous flow of YNB Sterile and Amp B. After 48 hour incubation period, C. albicans biofilm of 28.72 % is shown during dynamic scheme, whereas static scheme had C. albicans biofilm of 99.32 % indicating that the dynamic scheme provides a better efficacy compared to the static scheme.
Engineering a cell-friendly material in a form of lab-on-chip is the main goal of this study. The chip was made of polydimethyl siloxane (PDMS) with a surface modification to realize a groovy structure on its surface. This groovy surface was naturally and randomly designed via biomachining process. This measure was aimed to improve the cell attachment on the PDMS surface that always known as hydrophobic surface. The biomachined surface of mold and also products were characterized as surface roughness and wettability. The result shows that the biomachining process were able to be characterized in three classes of roughness on the surface of PDMS.
Maskless photolithograpy is an alternative method of conventional UV photolithograpy for microfabrication since its advantages of time and cost saving. For this reason, a visible-light based maskless photolithograpy is proposed as a part of biomachining process. Modification of the method is done by replacing light source of UV light to visible light, utilizing commercial DLP projector and changing the material removal process that generally uses echant with biomachining process. The process was done by using the profile generated by computer then displayed through a commercial DLP projector shining speciment test. Focusing lens placed under the projector to draw the focal point and reduces the size of the profile. The best parameter was determined by setring exposure time, developing time, variation profiles, focusing, colors combination and optical aspect. Using a commercial projector maskless photolithography on a negative resist tone successfully performed. The best characteristic was obtained by placing the focusing lens 3X magnification within 3 cm below the projector and 14 cm above speciment test, color combination of black-light blue (R = 0, G = 176, B = 240), with the timing of prebake 1 minute, exposure 7 minutes, postbake 5 minutes, developing 5 minutes produces the smallest profile 166 μm with 13,7 μm deviation. Biomachining process with bacteria Acidithiobacillus ferrooxidans NBRC 14262 on copper was also successfully performed with the smallest profile of 180 μm with 26 μm deviation.
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