Sensors and Actuators A 139 (2007) 139–144 DNA purification silicon chip Hong Miao Ji a,∗ , Victor Samper a , Yu Chen a , Wing Cheong Hui a , Hui Jen Lye b , Fatimah Bte Mustafa c , Ai Cheng Lee a,b , Lin Cong c , Chew Kiat Heng c , Tit Meng Lim b a Institute of Microelectronics, Singapore b Department of Biological Sciences, National University of Singapore, Singapore c Department of Pediatrics, National University of Singapore, Singapore Received 1 August 2006; received in revised form 16 May 2007; accepted 25 May 2007 Available online 3 June 2007 Abstract A silicon microchip has been developed for purification of deoxyribonucleic acid (DNA) from human blood based on the known affinity of DNA to silica under high chaotropic salt conditions. The chip comprises several components which include a micromixer, microfilter, microbinder and two microvalves to perform the functions of the mixing, filtering, purification and fluidic control; and yet it can be accomplished by a simple mask process flow process. Original human blood sample which is a mixture of many components, including white blood cells (WBC), red blood cells (RBC), platelets, plasma, etc., can be used directly as the input sample. After cell sorting, cell lysing, DNA binding, eluting and cleaning processes, pure DNA has been extracted for the white blood cells. An average of 10 ng DNA/l blood was able to be extracted from this fully integrated DNA extraction chip. The purity of the eluted DNA was evaluated by optical density at wavelengths of 260nm and 280nm. Tests results showed that the most DNA solution eluted was free from RNA and protein contamination. © 2007 Elsevier B.V. All rights reserved. Keywords: DNA extraction; Preparation; Purification; Micromixer; Microvalve; Microbinder; Microfilter 1. Introduction Conventional DNA analysis of a biological sample often involves the extraction of high quality DNA. The extraction pro- cess requires several laborious steps and the results are highly depending on the technician’s skills. Faster extraction speed and ease of use are the important aspects to be addressed for mak- ing DNA microextractor an economical and high throughput purification process. A DNA extraction method that is based on microfluidics offers many advantages, such as full automation of the process, portable instrumentation for field or point-of-care applications, small input sample and small chemical volumes requirement [1,2]. Many laboratories have been focusing their attention on the miniaturization of DNA analytical systems such as elec- ∗ Corresponding author. E-mail address: jihm@ime.a-star.edu.sg (H.M. Ji). trophoresis and PCR amplification devices [3–8], however, the miniaturization of the upstream tools for DNA extraction has been reported less frequently. Although few have demonstrated the use of microbeads inside microfluidic chips to extract DNA [8] or even more a complete system [9,10], it still use magnetic bead-based cell capture, cell pre-concentration and purification. It will be difficult to integrate all these components together for mass production. A silicon-based microfluidic chip to isolate DNA from white blood cells has been reported but it involves very complex structures including multiple layers of silicon chips [11]. Here, a simple micromachined silicon chip has been devel- oped for purification of DNA from blood. It will extract pure DNA from original whole human blood which is like a cocktail mixed with white blood cells (WBC), red blood cells (RBC), platelets and plasma. This chip comprises many different microfluidic components, such as micromixer, micro- filter, microbinder and microvalves in one single layer. It utilizes the special characteristic of the affinity of DNA to silica under high chaotropic salt conditions as the main 0924-4247/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.sna.2007.05.033