Surface Tension-Based Alignment of Microfibers on Hydrophilic–Superhydrophobic Grooved Surfaces

Abstract

Alignment and orderly distribution of microfibers have a major effect on the mechanical, electrical, and thermal properties of the fiber reinforced materials, biomimetic materials, and soft microsensors. However, it is still a challenging task to precisely align and distribute microfibers and construct complex patterns. This paper proposes a surface tension-based method to align and orderly distribute microfibers. A model was developed to simulate the surface tension driven alignment of the microfiber. We designed and fabricated hydrophilic–superhydrophobic grooved surfaces. We demonstrated that the microfibers can self-align to the hydrophilic–superhydrophobic grooves with different geometries. We studied the influence of the volume of the droplet and bias on the alignment success rate. The results indicate that the process can tolerate large variations of the bias and the volume, unless the volume is not enough to cover the groove. We further investigated the influence of the width of the groove on the alignment accuracy. The results show that the alignment accuracy is largely depending on the size difference between the groove and the microfiber; the better the size of the groove matches the size of the fiber, the higher the alignment accuracy will be achieved. The proposed method has great potential in construction of complex microstructures using microfibers.

Ejected Droplet-Directed Transportation and Self-Alignment of Microfibers to Micro Trenches

“…Recently, we have shown that microfibers can be aligned to microgrooves aided by a capillary gripper [19], [20]. The results of this initial investigation are promising.…”

Capillary Pick-and-Place of Glass Microfibers

“…We further studied the placement of microfibers on super hydrophilic/superhydrophobic grooved surfaces. It was previously reported that microfibers can self-align to the microgrooved structures [24] and the self-alignment has great potential for the alignment and distribution of microfibers, but the placement of the microfibers on the grooved structures have not been studied. This study mainly focuses on the placement accuracy and the placement speed of microfiber on hydrophilic-superhydrophobic microgrooves.…”

“…We have also developed a capillary gripper and demonstrated that the capillary gripper can be used to pick-and-place microchips [22] and transport miniaturized soft ribbons made of polydimethylsiloxane (PDMS) [23]. We further demonstrated that the self-alignment of microfibers using capillary force on hydrophilic/superhydrophobic grooved surfaces [24]. So far, the reported capillary force based methods and capillary grippers have shown great potentials in the construction of microstructures.…”

Self-calibration of micro-components based on manipulator guidance

“…A self-assembly method [26,27] was proposed based on shape recognition and capillary drive, and achieved selfalignment of 1000 micro-components with the receptor site at the same time. A surface tension-based method for the directional transport and self-alignment of micro-fibers has been investigated [28,29], which enables precise positioning and rapid alignment of micro-fibers. Combining robotic microassembly techniques with surface tension self-assembly techniques, a self-alignment strategy for micro-chips on patterned hydrophilic/hydrophobic different substrates is proposed [30], and the performance of the micro-assembly is evaluated for the release of micro-devices and high precision self-alignment with the substrate.…”