Mechanical-activated digital microfluidics with gradient surface wettability

Lab on a Chip ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 223-232 ◽  
Author(s):  
Lin Qi ◽  
Ye Niu ◽  
Cody Ruck ◽  
Yi Zhao
Keyword(s):  
Digital Microfluidics ◽  
Hydrophobic Surface ◽  
Surface Wettability ◽  
Long Distance ◽  
Droplet Motion ◽  
Surface Patterns ◽  
Droplet Manipulation ◽  
Gradient Surface

Long-distance droplet motion and selective droplet manipulation on repeated hydrophobic surface patterns with gradient wettability by in-plane cyclic vibration.

scholarly journals Electrowetting on Dielectric (EWOD) Device with Dimple Structures for Highly Accurate Droplet Manipulation

2019 ◽  
Vol 9 (12) ◽  
pp. 2406 ◽  
Author(s):  
Katsuo Mogi ◽  
Shungo Adachi ◽  
Naoki Takada ◽  
Tomoya Inoue ◽  
Tohru Natsume
Keyword(s):  
High Speed ◽  
Thin Sheet ◽  
Digital Microfluidics ◽  
Three Dimensional ◽  
Substrate Type ◽  
Droplet Motion ◽  
Electrowetting On Dielectric ◽  
Flat Substrate ◽  
Single Substrate ◽  
Droplet Manipulation

Digital microfluidics based on electrowetting on dielectric (EWOD) devices has potential as a fundamental technology for the accurate preparation of dangerous reagents, the high-speed dispensing of rapidly deteriorating reagents, and the fine adjustment of expensive reagents, such as the preparation of for positron emission tomography (PET). To allow single substrate type EWODs to be practically used in an automatic operation system, we developed a dimple structure as a key technique for a highly accurate droplet manipulation method. The three-dimensional shape of the dimple structure is embossed onto a disposable thin sheet. In this study, we confirmed that the dimple structure can suppress unintended droplet motion caused by unidentified factors. In addition, the stability of the droplets on the dimple structures was evaluated using a sliding experiment. On a flat substrate, the success rate of a droplet motion was lower than 70.8%, but on the dimple structure, the droplets were able to be moved along the dimple structures correctly without unintended motion caused by several environmental conditions. These results indicated that the dimple structure increased the controllability of the droplets. Hence, the dimple structure will contribute to the practical application of digital microfluidics based on single substrate type EWODs.

Droplet Manipulation Over a Hydrophobic Surface With Roughness Patterns

Volume 4 ◽  
2004 ◽  
Author(s):  
Jia-Hui Chen ◽  
Jing-Tang Yang ◽  
Ker-Jer Huang ◽  
Chih-Sheng Yu ◽  
Joseph Yih-Chiuen Hu
Keyword(s):  
Contact Angle Hysteresis ◽  
Hydrophobic Surface ◽  
Textured Surfaces ◽  
Parylene C ◽  
Droplet Motion ◽  
Power Sources ◽  
Drag Forces ◽  
External Power ◽  
Droplet Manipulation ◽  
Novel Concept

A novel concept is proposed to manipulate droplets without external power sources in this study. The proposed device is a hydrophobic surface containing specific roughness gradients, which is composed of several textured regions with gradually increased structural roughness. Four types of hydrophobic materials, AZ6112, Teflon, Parylene C, and plasma polymerization fluorocarbon film (PPFC), are adopted to fabricate the textured surfaces and tested. Actuating forces come from the different Laplace pressures exerting on a droplet across different hydrophobic surfaces, whereas dragging forces come from the contact angle hysteresis. Two patterns of devices are shown in this article, the chain-shaped and the concentric circular. The former functions as a droplet transporting route and the latter provides both transporting and orientation functions. Theoretical estimation and experimental verification of the droplet motion, including actuation and drag forces, on the device are conducted. Optimal design will be achieved based on accurate estimations of the acting forces. The proposed device provides a simpler fabrication process and shows better biocompatibility for droplet manipulation in microfluidic systems.

Numerical study of droplet motion on discontinuous wetting gradient surface with rough strip

2021 ◽  
Vol 33 (1) ◽  
pp. 012111
Author(s):  
Wenbin Li ◽  
Jiacai Lu ◽  
Grétar Tryggvason ◽  
Ying Zhang
Keyword(s):  
Numerical Study ◽  
Droplet Motion ◽  
Gradient Surface

scholarly journals Scaling Electrowetting with Printed Circuit Boards for Large Area Droplet Manipulation

MRS Advances ◽  
2018 ◽  
Vol 3 (26) ◽  
pp. 1475-1483 ◽  
Author(s):  
Udayan Umapathi ◽  
Samantha Chin ◽  
Patrick Shin ◽  
Dimitris Koutentakis ◽  
Hiroshi Ishii
Keyword(s):  
Printed Circuit Boards ◽  
Dielectric Material ◽  
Point Of Care ◽  
Digital Microfluidics ◽  
Microfluidic Devices ◽  
Electrode Arrays ◽  
Large Area ◽  
Lab On Chip ◽  
Electrowetting On Dielectric ◽  
Droplet Manipulation

ABSTRACTDroplet based microfluidics (digital microfluidics) with Electrowetting on dielectric (EWOD) has gained popularity with the promise of being technology for a true lab-on-chip device with applications spanning across assays/library prep, next-gen sequencing and point-of-care diagnostics. Most electrowetting device architecture are linear electrode arrays with a shared path for droplets, imposing serious limitations -- cross contamination and limited number of parallel operations. Our work is in addressing these issues through large 2D grid arrays with direct addressability providing flexible programmability.Scaling electrowetting to larger arrays still remains a challenge due to complex and expensive cleanroom fabrication of microfluidic devices. We take the approach of using inexpensive PCB manufacturing, investigate challenges and solutions for scaling electrowetting to large area droplet manipulation. PCB manufactured electrowetting arrays impose many challenges due to the irregularities from process and materials used. These challenges generally relate to preparing the surface that interfaces with droplets -- a dielectric material on the electrodes and the top most hydrophobic coating that interfaces with the droplets. A requirement for robust droplet manipulation with EWOD is thin (<10um) hydrophobic dielectric material which does not break down at droplet actuation voltages (AC/DC, 60V to 200V) and has a no droplet pinning. For this, we engineered materials specifically for large area PCBs.Traditionally, digital microfluidic devices sandwich droplets between two plates and have focussed on sub-microliter droplet volumes. In our approach, droplets are on an open surface with which we are able to manipulate droplets in microliter and milliliter volumes. With milliliter droplet manipulation ability on our electrowetting device, we demonstrate “digital millifluidics”. Finally, we report the performance of our device and to motivate the need for large open arrays we show an example of running multiple parallel biological experiments.

Effects of Titanium Surface Wettability on Osteoblast Behavior In Vitro

2020 ◽  
Vol 985 ◽  
pp. 64-68
Author(s):  
Kenta Nisogi ◽  
Satoshi Okano ◽  
Sengo Kobayashi ◽  
Kensuke Kuroda ◽  
Takeaki Okamoto
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Titanium Surface ◽  
Pure Titanium ◽  
Hydrophobic Surface ◽  
Surface Wettability ◽  
In Vitro Assays ◽  
Water Contact ◽  
Heat Treated

Surface wettability is thought to influence the osteoconductivity of bone-substituting materials; however, the effects of surface wettability on osteoblast behavior are not well understood. In this study, we prepared both an as-polished pure titanium with a water contact angle (WCA) of 57° and heat-treated pure titanium with more hydrophobic surface and WCAs of 68°-98°. The effects of the surface wettability of pure titanium on osteoblast behaviors were evaluated by in vitro assays. Compared with the as-polished titanium, the proliferation rate of osteoblast increased on heat-treated titanium. This suggested that surface wettability affects osteoblast behaviors, meaning osteoconductivity is influenced by surface wettability.

Experimental and Model Studies of Various Size Water Droplet Impacting On a Hydrophobic Surface

2021 ◽  
Author(s):  
Abba Abdulhamid Abubakar ◽  
Bekir Sami Yilbas ◽  
Hussain Al-Qahtani ◽  
Ghassan Hassan ◽  
Mubarak Yakubu ◽  
...  
Keyword(s):  
High Speed ◽  
Hydrophobic Surface ◽  
Sample Surface ◽  
Liquid Pressure ◽  
Droplet Deformation ◽  
Droplet Motion ◽  
Droplet Shape ◽  
Model Studies ◽  
High Speed Data ◽  
Droplet Liquid

Abstract Impacting droplet on a hydrophobic surface is investigated and droplet size effect on impacting properties is examined. Liquid pressure variation inside droplet is numerically simulated in the impacting and rebounding periods. Droplet motion on impacted hydrophobic surface is monitored using a high-speed recording system. We showed that predictions and high-speed data for droplet shape and geometric features appear to be almost identical in the spreading and retraction of the droplet on sample surface. Increased volume of droplet gives rise to the peak pressure enhancement in droplet liquid during impact. The maximum droplet height remains larger for large volume droplets in both spreading and retraction cycles. Increasing size of droplet enlarges the wetting diameter on the impacted surface during droplet deformation on sample surfaces. The rate of peak velocity of the spreading surface of the droplet is faster for small droplets as compared to that corresponding to large droplets. The ratio of spreading period over the retraction period of the droplet becomes small for droplets with small size.

Anti-Icing Property of the Prepared Super-Hydrophobic Octadecyltrichlorosilane (OTS) Film by Phase Separation Method

2013 ◽  
Vol 663 ◽  
pp. 331-334
Author(s):  
Liang Ge ◽  
Jin Yuan Yao ◽  
Hong Wang ◽  
Gui Fu Ding
Keyword(s):  
Contact Angle ◽  
Phase Separation ◽  
Heterogeneous Nucleation ◽  
Hydrophobic Surface ◽  
Separation Method ◽  
Surface Wettability ◽  
Nucleation Theory ◽  
Ice Formation ◽  
Water Droplets ◽  
Hydrophobic Surfaces

In this paper, we prepared an octadecyltrichlorosilane(OTS) super-hydrophobic film using phase separation method to demonstrate the anti-icing property of super-hydrophobic surfaces. We investigated the super-hydrophobicity of the surface in -5°C environment, as well as the icing process of water droplets on the surface which proceeded at the temperature low to -15°C. We found that the prepared OTS film retained its super-hydrophobicity in the -5°C environment by the measurement of contact angle. It was observed that the icing progress of water droplets on the super-hydrophobic surface was greatly retarded. Based on the classical heterogeneous nucleation theory, it concluded that the ice formation is directly related to the surface wettability. This research would be beneficial to the preparation of anti-icing films.

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