Ikjoo Byun

Transfer of thin Au films to polydimethylsiloxane (PDMS) with reliable bonding using (3-mercaptopropyl)trimethoxysilane (MPTMS) as a molecular adhesive

This paper describes the transfer of thin gold films deposited on rigid silicon substrates to polydimethylsiloxane (PDMS) with reliable and strong bonding. Modification of the Au surfaces with (3-mercaptopropyl)trimethoxysilane (MPTMS) as a molecular adhesive was carried out to promote adhesion between Au and PDMS. The degree of bonding with respect to the concentration of MPTMS, treatment time and methods of deposition was investigated by a simple adhesion test using two different adhesive tapes. The effect of hydrolysis of MPTMS is discussed based on the bonding mechanism of MPTMS to the PDMS prepolymer. Also, the adsorption of MPTMS on Au deposited by different methods is discussed. The results indicate that liquid deposition of MPTMS provides the strongest adhesion between Au and PDMS among the different deposition methods and the different linker molecules. Based on these studies, the Au patterns with linewidth of less 2 μm were successfully transferred to PDMS with reliable and strong bonding in a full 3 inch wafer scale, using a dry peel-off process. (Some figures may appear in colour only in the online journal)

Microcontact printing using a flat metal-embedded stamp fabricated using a dry peel-off process

A microcontact printing method using a flat metal-embedded polydimethylsiloxane (PDMS) stamp has been demonstrated. Metal patterns embedded in the PDMS stamp act as a molecular transport barrier. The flat stamp avoids the mechanical deformation of the stamp tip which is a crucial problem when printing the stamp onto a substrate.

Fabrication of PDMS Nano-Stamp by Replicating Si Nano-Moulds Fabricated by Interference Lithography

In this research, a polydimethylsiloxane nanostamp for nanocontact printing was fabricated by replicating Si nanomoulds. Si moulds of various shapes and sizes were fabricated by interference lithography and deep reactive ion etching. As an anti-adhesion layer, octadecyltrichlorosilane was treated on Si nanomoulds. Further, superhydrophobic surfaces were obtained by self-assembled monolayer treatment on Si nanostructures.

Elucidating the mechanism of the considerable mechanical stiffening of DNA induced by the couple Zn 2+ /Calix[4]arene-1,3-O-diphosphorous acid

The couple Calix[4]arene-1,3-O-diphosphorous acid (C4diP) and zinc ions (Zn2+) acts as a synergistic DNA binder. Silicon NanoTweezer (SNT) measurements show an increase in the mechanical stiffness of DNA bundles by a factor of >150, at Zn2+ to C4diP ratios above 8, as compared to Zinc alone whereas C4diP alone decreases the stiffness of DNA. Electroanalytical measurements using 3D printed devices demonstrate a progression of events in the assembly of C4diP on DNA promoted by zinc ions. A mechanism at the molecular level can be deduced in which C4diP initially coordinates to DNA by phosphate-phosphate hydrogen bonds or in the presence of Zn2+ by Zn2+ bridging coordination of the phosphate groups. Then, at high ratios of Zn2+ to C4diP, interdigitated dimerization of C4diP is followed by cross coordination of DNA strands through Zn2+/C4diP inter-strand interaction. The sum of these interactions leads to strong stiffening of the DNA bundles and increased inter-strand binding.

Fabrication of micro-heaters embedded in PDMS using a dry peel-off process

This paper describes a reliable fabrication method of micro-heaters embedded in polydimethylsiloxane (PDMS). Gold patterns are transferred and embedded to the PDMS from a silicon substrate, by peeling off. The surface adhesion among silicon substrate, Au patterns, and PDMS is modified with self-assembled monolayers. Therefore, micro-heaters embedded in PDMS can be fabricated by a simpler and easier way compared to conventional methods. The thermal characterization of micro-heaters and PDMS device is carried out by electrical and infrared thermo-microscopic measurements. The experimental results well agree with the numerical analysis performed by finite element method.