Volume 6 • Issue 4 • 1000185 J Biosens Bioelectron ISSN: 2155-6210 JBSBE, an open access journal Research Article Open Access Biosensors & Bioelectronics J o u r n a l o f B i o s e n s o r s & B i o e l e c t r o n i c s ISSN: 2155-6210 Yang et al., J Biosens Bioelectron 2015, 6:4 http://dx.doi.org/10.4172/2155-6210.1000185 *Corresponding author: Lijun Yang, Microsystem Lab, School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu, China, Tel: +86-025-84315031; E-mail: fulisayang@163.com Received October 05, 2015; Accepted October 12, 2015; Published October 21, 2015 Citation: Yang L, Lu B, Zhu L, Zhu X (2015) Fabrication of Liquid Molds using Drop-on-demand Printing Technology for Bio-Pdms Miroluidic Devices. J Biosens Bioelectron 6: 185. doi:10.4172/2155-6210.1000185 Copyright: © 2015 Yang L, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Keywords: Liquid molds; Drop-on-demand printing; Bio-PDMS microluidic device; Hydrophilic; Overlap Introduction In the last few decades, biological microluidic devices have been attracting considerable interests in the area of biosensors and bioelectronics due to the characteristics of less consumption of samples, less analysis time and portability [1]. Recently, there have been many studies on biosensors and bioelectronics using biological mircoluidic devices [2,3]. Polydimethylsiloxane (PDMS), a silicon-based polymer, is oten the preferred material for the prototyping of microluidic devices as it is easily to be bonded, transparent ,durable, non-luorescent, biocompatible and nontoxic [4,5]. he most widely used method for PDMS microluidic device fabrication is sot lithography. However, the fabrication of master molds is the key step of PDMS microluidic device preparation with a sot lithography method. To date, there have been many methods developed to fabricate master molds in bio-PDMS miroluidic devices such as, UV exposure, ice-water patterning [6], the etching of copper, liquid molding on paper [7] and wax printing on paper [8]. However, most of these methods have some limitations, making the fabrication expensive, complex and not easy. he UV exposure on photosensitive polymers needs photomasks and organic solvent [9], and the equipment was complicated and the fabrication must be carried in an ultra-clean environment. he etching of copper required masks and additional etching steps [10], and the solution needed in the fabrication was toxic. Liu X fabricated PDMS micro-devices with a “liquid-molding” method [11], but however, the process is complex and diiculty. Because the method needs to photo-lithographically fabricate micro-patterns on a silanized glass substrate to form hydrophilic/hydrophobic surfaces and to fabricate 3D patterns of a liquid via dip-coating the substrate in a polar solution. We prepared a PDMS microluidic device based on drop-on-demand generation of wax molds [12], in which the wax droplets were dispersed on the substrate to form the wished patterns at the desired times and positions without contact with the substrate. However, the surface of the micro-channels in the micofuidic devices was rough and the width of the channel was large. In this paper, a new droplet-on-demand printing method [13-15] was described to fabricate liquid molds which were used in Bio-PDMS microluidic devices on a hydrophilic glass substrate using a glycerol solution. he liquid droplets were ejected from a glass micro-nozzle onto the glass substrate based on microludic pulse interior force to form diferent liquid molds. Finally, the depth, the width and the surface roughness of the micro-channel were characterized. Materials and Method Glycerol AR was purchased from Sinopharm Chemical Reagent Co., Ltd. Sylgard 184 was supplied by the Dow Corning Corporation. he TiO 2 nanoparticals(NPs) with the diameter of less than 4 nm was purchased from Shenzhen jing cai chemi cal co.,ltd. he borosilicate glass capillary (1.0 mm × 0.6 mm ×100 mm) was purchased from Beijing Zhengtianyi Scientiic And Trading Co., Ltd. he micro-nozzles used in this paper was made by a Microelectrode puller (MODEL P-2000) and a platinum resistance wire (MF-900.NARISHIGE) with the borosilicate glass capillary to get the outlet inner diameters. Figure 1 shows the fabrication process of the micro-nozzles with the platinum resistance wire in four steps. Firstly, the glass capillary tip was placed above the glass micro-ball. hen the glass micro-ball was heated by controlling the voltage and the tip was cut of at the desired position. Aterward, the tip was placed in front of the glass micro-ball. At last, the tip was forged to form a micro-nozzle by heating the micro-ball through controlling the voltage. In the DOD printing system, as is shown in Figure 2, a glass micro- nozzle illed with the 50% glycerol solution is ixed with the PZT actuator through a connecting device. he liquid in the micro-nozzles was jetted on the glass substrate to form liquid droplets with diferent diameters by the pulse inertia force supplied by a PZT actuator. he glass substrates used in this paper were hydrophilic treated by TiO 2 Fabrication of Liquid Molds using Drop-on-demand Printing Technology for Bio-Pdms Mirofluidic Devices Lijun Yang*, Baochun Lu, Li Zhu, and Xiaoyang Zhu Microsystem Lab, School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu, China Abstract A simple and easy method is demonstrated for the fabrication of liquid molds which was used for the fabricaion of bio-polydimethylsiloxan (Bio-PDMS) miroluidic devices based on a novel drop-on-demand (DOD) printing technology. The liquid molds were DOD printed well on the hydrophilic glass substrate which was treated with a TiO 2 nanoparticles (TiO 2 NPs) solution at the overlap of 30%. Then the PDMS concave molds were fabricated well by being replicated from the liquid molds and were bonded with another PDMS substrate to form a Bio-PMDS miroluidic device. The micro-channel which the width and the height were about 100 μm and 8 μm was fabricated and the surface roughness of the micro-channel with the 100×320 μm 2 area was about 179 nm measured by a white light interferometer. The experimental results showed that the width of micro-channel in the Bio-PDMS microluidic device was small and the surface of the micro-channel was smooth.