Details

Autor(en) / Beteiligte

• Nelson, Wyatt C
• Sen, Prosenjit
• Kim, Chang-Jin “CJ”

Titel

Dynamic Contact Angles and Hysteresis under Electrowetting-on-Dielectric

Ist Teil von

• Langmuir, 2011-08, Vol.27 (16), p.10319-10326

Ort / Verlag

Washington, DC: American Chemical Society

Erscheinungsjahr

2011

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• By designing and implementing a new experimental method, we have measured the dynamic advancing and receding contact angles and the resulting hysteresis of droplets under electrowetting-on-dielectric (EWOD). Measurements were obtained over wide ranges of applied EWOD voltages, or electrowetting numbers (0 ≤ Ew ≤ 0.9), and droplet sliding speeds, or capillary numbers (1.4 × 10–5 ≤ Ca ≤ 6.9 × 10–3). If Ew or Ca is low, dynamic contact angle hysteresis is not affected much by the EWOD voltage or the sliding speed; that is, the hysteresis increases by less than 50% with a 2 order-of-magnitude increase in sliding speed when Ca < 10–3. If both Ew and Ca are high, however, the hysteresis increases with either the EWOD voltage or the sliding speed. Stick–slip oscillations were observed at Ew > 0.4. Data are interpreted with simplified hydrodynamic (Cox–Voinov) and molecular-kinetic theory (MKT) models; the Cox–Voinov model captures the trend of the data, but it yields unreasonable fitting parameters. MKT fitting parameters associated with the advancing contact line are reasonable, but a lack of symmetry indicates that a more intricate model is required.