In this report, microfluidic chips, based on PDMS material, fabricated by soft lithography with the length-and-diameter ratio of channel 3000 times, have been fabricated for the research on biomedical orientation. | Journal of Science and Technology 54 (1A) (2016) 168-174 FABRICATING THE MICROFLUIDIC CHIP WITH LENGTH-AND-DIAMETER RATIO OF CHANNEL AROUND 3000 Le Thuy Thanh Giang1, *, Pham Minh Tuan1, Tran Hong Nhan1, Tran Quang Trung1 Solid State Department, Faculty of Physics – Engineering Physics, University of Science, Vietnam National University, 227 Nguyen Van Cu St., Ward 4, District 5, Ho Chi Minh City. 1 * Email: lttgiang@ Received: 03 September 2015; Accepted for publication: 26 October 2015 ABSTRACT Microfluidics is a device that accurately controls the motion of fluid flow with a very small amount of liquid. This field has been studied with many empirical applications in physics, chemistry, biochemistry, nanotechnology and biotechnology. Depending on particular application, the length-and-diameter ratio of channel is designed specifically in order to gain the highest efficiency for physical response and chemical reaction, etc. In this report, microfluidic chips, based on PDMS material, fabricated by soft lithography with the length-and-diameter ratio of channel 3000 times, have been fabricated for the research on biomedical orientation. Illustration of microfluidic chip with straight and spiral shape and the length-and-diameter ratio of channel around 3000. Keywords: microfluidic chip, PDMS, soft-lithography. 1. INTRODUCTION In the past two decades, the microfluidic chips, which are able to miniaturize the facilities in experiments with the micro volumes of fluids (µL, nL, pL or fL), demonstrated useful abilities and practical applications in the multidisciplinary field, such as health diagnosis, genome and protein research, chemical analysis, environmental assessment and detection of pathogens, as well as in the field of other scientific studies [1 - 4]. The equipment using Micro Total Analysis Systems ( TAS) is more advantageous than traditional sophisticated, expensive and closed systems, especially in the ability to control fluid flow precisely,