Inseong You

One-step modification of superhydrophobic surfaces by a mussel-inspired polymer coating.

A bio-inspired approach for superhydrophobic surface modification was investigated. Hydrophilic conversion of the superhydrophobic surface was easily achieved through this method, and the superhydrophobic-hydrophilic alternating surface was generated by the method combined with soft-lithography. The resulting patterned surface showed high water adhesion property in addition to superhydrophobic property.

Enhancement of Blood Compatibility of Poly(urethane) Substrates by Mussel-Inspired Adhesive Heparin Coating

Heparin immobilization on surfaces has drawn a great deal of attention because of its potential application in enhancing blood compatibility of various biomedical devices such as catheters, grafts, and stents. Existing methods for the heparin immobilization are based on covalent linkage formation and electrostatic interaction between substrates and heparin molecules. However, complicated multistep procedures and uncontrolled desorption of heparin are limitations of these methods. In this work, we report a new heparin derivative that exhibits robust adhesion on surfaces. The derivative, called hepamine, was prepared via conjugation of dopamine, a mussel-inspired adhesive moiety, onto a heparin backbone. Immersion of poly(urethane) substrates into an aqueous solution of hepamine resulted in robust heparin coating of the poly(urethane), the most widely used polymeric material for blood-contacting medical devices. The hepamine-coated poly(urethane) substrate showed significant inhibition of blood coagulation and platelet adhesion. The use of hepamine for surface modification is advantageous for several reasons: for example, no chemical pretreatment of the substrates is necessary, and surface functionalization is a simple, one-step procedure. Thus, the heparin immobilization method described herein is an excellent alternative approach for the introduction of heparin molecules onto surfaces.

Material-independent fabrication of superhydrophobic surfaces by mussel-inspired polydopamine

This study reports methods for general preparation of superhydrophobic surfaces on any type of material surface using mussel-inspired poly(dopamine) (pDA). The use of pDA presents several advantages over conventional superhydrophobic fabrication methods: development of superhydrophobicity in a material-independent manner, enhancement of mechanical stability, decreases in angle hysteresis, and applicability to 3D objects.

Surface-tension-confined microfluidics and their applications.

This article is a brief overview of the emerging microfluidic systems called surface-tension-confined microfluidic (STCM) devices. STCM devices utilize surface energy that can control the movement of fluid droplets. Unlike conventional poly(dimethylsiloxane)-based microfluidics which confine the movement of fluids by three-dimensional (3D) microchannels, STCM systems provide two-dimensional (2D) platforms for microfluidics. A variety of STCM devices have been prepared by various micro-/nanofabrication strategies. Advantages of STCM devices over conventional microfluidics are significant reduction of energy consumption during device operation, facile introduction of fluids onto 2D microchannels without the use of a micropump, increased flow rate in a special type of STCM device, among others. Thus, STCM devices can be excellent alternatives for certain areas in microfluidics. In this Minireview, fabrication methods, operating modes, and applications of STCM devices are introduced.

Bio-inspired surface treatment on touch screen panels (TSPs) for adhesion enhancement

Immersion of substrates in a dilute aqueous solution of bio-inspired building blocks resulted a deposition of polydopamine thin film on the substrate. The Self-polymerization speed measured by ellipsometry was 1.6 nm/hr. Strong catalyst was added in order to enhance the speed. The resulting speed was increased from 1.6 nm/hr to 30 nm/hr. Bio-inspired surface treated PET and ITO-PET substrates with various treatment times were assembled with FPC using commercial acrylic ACF. As a result, adhesion strength between PET substrates and FPC was enhanced dramatically from below 10 gf/cm to over 500 gf/cm even when the treatment time was 5 min. Electrical contact resistance did not show any notable changes. It was presumably due to the sufficiently low thickness (2.5 nm) of bio-inspired thin film on the electrode.