Joonwon Kim

Frost formation can cause operational difficulty and efficiency loss for many facilities such as aircraft, wind turbines, and outdoor heat exchangers. Self-propelled jumping by condensate droplets on superhydrophobic surfaces delays frost formation, so many attempts have been made to exploit this phenomenon. However, practical application of this phenomenon is currently unfeasible because many processes to fabricate the superhydrophobic surfaces are inefficient and because self-propelled jumping

This paper reports a dramatic reduction of liquid droplet flow resistance by engineering the surfaces into nanomechanical hydrophobic structures that show a contact angle over 175/spl deg/. Flow resistances of droplets on open surfaces as well as in confined microchannels (between surfaces) have been measured with significant reduction of flow resistance (over 99% and over 95%, respectively) compared with a surface of the same material.

We report the drop impact characteristics on four hydrophobic surfaces with different well-scale structures (smooth, nano, micro, and hierarchical micro/nano) and the effects of those structures on the behavior of water drops during impact. The specimens were fabricated using silicon wet etching, black silicon formation, or the combination of these methods. On the surfaces, the microstructures form obstacles to drop spreading and retracting, the nanostructures give extreme water-repellency, and

Abstract Embolization, which is a minimally invasive endovascular treatment, is a safe and effective procedure for treating vascular malformations (e.g., aneurysms). Hydrogel microfibers obtained via spatiotemporally controllable in situ photocrosslinking exhibit great potential for embolizing aneurysms. However, this process is challenging because of the absence of biocompatible and morphologically stable hydrogels and the difficulty in continuously spinning the microfibers via in situ photocro

Abstract Flexible capacitive‐type touch sensors have significant potential in robotics, foldable displays, and wearable electronics. However, the general parallel‐plate structure of these sensors unintentionally changes initial values and sensitivity in various situations, such as in electromagnetic interference (EMI) and bending. In the present study, a double side EMI‐shielded bending‐insensitive capacitive‐type touch sensor is proposed with a linear response over a wide detection range. The d

We report a simple, efficient microfluidic array system for reliable isolation of cells. A microfluidic array chip, integrated with a size-based cell bandpass filter, provides the unprecedented capability of organizing single cells from a population containing a wide distribution of sizes.

Abstract Multilayered 3D vascular replicas incorporating the complementary advantages of elastomers and hydrogels can serve as a training platform to realistically simulate endovascular intervention, the preferred therapeutic procedure for cardio‐cerebrovascular disease. However, the fabrication process is challenging because of the difficulty in uniformly coating a thin hydrogel layer only on the inner surface of tortuous 3D vascular replicas composed of an elastomer monolayer. This study propo