Browsing by Author "Cezan, S. D."

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Open Access
Artificial heliotropism and nyctinasty based on optomechanical feedback and no electronics
(Mary Ann Liebert, 2018) Baytekin, B.; Cezan, S. D.; Baytekin, H. T.; Grzybowski, B. A.
Although plants are typically not considered an inspiration for designing motile robots, they do perform a variety of intricate motion patterns, including diurnal cycles of sun tracking (heliotropism) and leaf opening (nyctinasty). In real plants, these motions are controlled by complex, feedback-based biological mechanisms that, to date, have been mimicked only in computer-controlled artificial systems. This work demonstrates both heliotropism and nyctinasty in a system in which few simple, but strategically positioned thermo-responsive springs and lenses form a feedback loop controlling these motions and substantiating a behavioral analogy to "plants." In particular, this feedback allows the "artificial plant" to reach and stabilize at a metastable position in which the solar flux on the "plants" and the solar power "leaves" are maximized. Unlike many soft robotic systems, our "plants" are completely autonomous, in that, they do not require any external controls or power sources. Bioinspired designs such as this could be of interest for soft robotic systems in which materials alone - rather than power-consuming electronic circuitry - control the motions.
Open Access
Minimizing friction, wear, and energy losses by eliminating contact charging
(American Association for the Advancement of Science, 2018) Sayfidinov, K.; Cezan, S. D.; Baytekin, Bilge; Baytekin, H. T.
One-fourth of the global energy losses result from friction and wear. Although friction and tribocharging were presented to be mutually related, reduction of friction and wear by eliminating tribocharges on common polymers, and decrease of power losses in devices with polymer parts were not shown to date. Here, we demonstrate that for common polymers, friction—which is strongly related to surface charge density—can be notably reduced by various methods of tribocharge mitigation, namely, corona discharging, solvent treatment, or placing a grounded conductor on the backside of one of the shearing materials. In our simple demonstrations, we found that by preventing tribocharge accumulation, a remarkable two-thirds of power loss during operation of simple mechanical devices with common polymers and plastic parts can be saved and wear can be reduced by a factor of 10. These demonstrations indicate important practical ramifications in mechanical systems with insulating parts. Copyright