Actively-controlled superhydrophobic surfaces

Abstract

Active superhydrophobic surface structures are actively-controlled surface structures exhibiting a superhydrophobic state and an ordinary state. Active superhydrophobic surface structures comprise an outer elastomeric covering defining an exposed surface, a controlled group of MEMS (micro-electro-mechanical system) actuators at least covered by the elastomeric covering, and, a controlled region of the exposed surface corresponding to the controlled group. The controlled region has a superhydrophobic state in which the controlled region is textured. The controlled region also has an ordinary state in which the controlled region is smooth (i.e., less textured than in the superhydrophobic state). Active superhydrophobic surface structures may be part of an apparatus that includes a controller and/or one or more sensors. The controller, sensors, and the controlled region may form a feedback loop in which the active superhydrophobic surface is actively controlled.

1 . An active superhydrophobic surface structure comprising:
 an outer elastomeric covering defining an exposed surface;   a controlled group of one or more MEMS actuators at least covered by the outer elastomeric covering; and   a controlled region of the exposed surface corresponding to the controlled group;   wherein the controlled region has a superhydrophobic state in which the controlled region is textured and an ordinary state in which the controlled region is smooth.   
     
     
         2 . The active superhydrophobic surface structure of  claim 1 , wherein the controlled region in the superhydrophobic state is superhydrophobic and icephobic, and wherein the controlled region in the ordinary state is hydrophobic. 
     
     
         3 . The active superhydrophobic surface structure of  claim 1 , wherein a contact angle of water with the controlled region in the superhydrophobic state is greater than a contact angle of water with the controlled region in the ordinary state. 
     
     
         4 . The active superhydrophobic surface structure of  claim 1 , wherein, in the superhydrophobic state, each MEMS actuator of the controlled group is activated to deform a portion of the controlled region and wherein, in the ordinary state of the controlled region, each MEMS actuator of the controlled group is deactivated and the controlled region is unaffected by the controlled group of MEMS actuators. 
     
     
         5 . The active superhydrophobic surface structure of  claim 1 , wherein the controlled region in the superhydrophobic state includes a plurality of microprotrusions, and wherein the one or more MEMS actuators are configured to selectively form the microprotrusions. 
     
     
         6 . The active superhydrophobic surface structure of  claim 1 , wherein the controlled region in at least one of the superhydrophobic state and the ordinary state includes a plurality of nanoprotrusions, and wherein the one or more MEMS actuators are configured to selectively form the nanoprotrusions. 
     
     
         7 . The active superhydrophobic surface structure of  claim 1 , further comprising a plurality of vibration generators configured to at least one of (a) selectively vibrate the controlled region and (b) selectively impart a sonic shock into the controlled region. 
     
     
         8 . The active superhydrophobic surface structure of  claim 1 , further comprising a heater configured to selectively heat the controlled region. 
     
     
         9 . The active superhydrophobic surface structure of  claim 1 , wherein the active superhydrophobic surface structure includes a plurality of controlled groups and a plurality of controlled regions corresponding to the controlled groups. 
     
     
         10 . An aircraft comprising:
 an aerodynamic component with a leading edge;   a controller;   one or more sensors; and   an active superhydrophobic surface structure including:
 an outer elastomeric covering defining an exposed surface; 
 a controlled group of one or more MEMS actuators at least covered by the outer elastomeric covering; and 
 a controlled region of the exposed surface corresponding to the controlled group; 
   wherein the controlled region has a superhydrophobic state in which the controlled region is textured and an ordinary state in which the controlled region is smooth;   wherein the active superhydrophobic surface structure is proximate to the leading edge; and   wherein the controller is configured to control the controlled region of the active superhydrophobic surface structure based at least on information from the sensors in a feedback loop.   
     
     
         11 . The aircraft of  claim 10 , wherein the controller is configured to transition the controlled region between the superhydrophobic state and the ordinary state by activating the one or more MEMS actuators of the controlled group to transition to the superhydrophobic state and by deactivating the one or more MEMS actuators of the controlled group to transition to the ordinary state. 
     
     
         12 . The aircraft of  claim 10 , wherein the controlled region in the superhydrophobic state is superhydrophobic and icephobic, and wherein the controlled region in the ordinary state is hydrophobic. 
     
     
         13 . An apparatus comprising:
 a body; and   an active superhydrophobic surface structure including:
 an outer elastomeric covering defining an exposed surface; 
 a controlled group of one or more MEMS actuators at least covered by the outer elastomeric covering; and 
 a controlled region of the exposed surface corresponding to the controlled group; 
   wherein the body includes the active superhydrophobic surface structure; and   wherein the controlled region has a superhydrophobic state in which the controlled region is textured and an ordinary state in which the controlled region is smooth.   
     
     
         14 . The apparatus of  claim 13 , wherein the body includes an aerodynamic component that has a leading edge, and wherein the active superhydrophobic surface structure is proximate to the leading edge. 
     
     
         15 . The apparatus of  claim 13 , further comprising a controller and one or more sensors. 
     
     
         16 . The apparatus of  claim 15 , wherein at least one of the sensors is configured to measure a measured property, wherein the measured property is at least one of a property of the exposed surface, a property of the apparatus, and a property of an environment proximate to the apparatus, wherein the measured property includes at least one of temperature, apparatus speed, wind speed, wind direction, apparatus orientation, exposed surface orientation, angle of attack, humidity, and pressure. 
     
     
         17 . The apparatus of  claim 15 , wherein one or more of the one or more sensors are configured to detect at least one of an environmental condition and an exposed surface condition. 
     
     
         18 . The apparatus of  claim 15 , wherein the controller is configured to control the controlled region based at least on information from the sensors in a feedback loop. 
     
     
         19 . The apparatus of  claim 15 , wherein the controller is configured to transition the controlled region between the superhydrophobic state and the ordinary state by activating the one or more MEMS actuators of the controlled group to transition to the superhydrophobic state and by deactivating the one or more MEMS actuators of the controlled group to transition to the ordinary state. 
     
     
         20 . The apparatus of  claim 15 , wherein the controller is configured to transition the controlled region from the ordinary state to the superhydrophobic state based upon a detection of condensation conditions, a detection of icing conditions, a forecast of condensation conditions, and/or a forecast of icing conditions.