Kinetic electronics: Monolithic processing of a layered flexible robotic actuator film for simple film microrobot fabrication

Low-invasive soft robotic techniques can potentially be used for developing next-generation body–machine interfaces. Most soft robots require complicated fabrication processes involving 3D printing and bonding/assembling. In this letter, we describe a monolithic soft microrobot fabrication process for the mass production of soft film robots with a complex structure by simple 2D processing of a robotic actuator film. The 45 μg/mm^2 lightweight film robot can be driven at a voltage of CMOS compatible 5 V with 0.15 mm^-1 large curvature changes; it can generate a force 5.7 times greater than its self-weight. In a durability test, actuation could be carried out over 8000 times without degradation. To further demonstrate this technique, three types of film robots with multiple degrees of freedom and moving illuminator robot were fabricated. This technique can easily integrate various electrical circuits developed in the past to robotic systems and can be used for developing advanced wearable sensing devices; It can be called “Kinetic electronics.”

Dielectric Behaviour of PVA and Cornstarch Polymer Blend Electrolytes

Simple film preparation method of solution casting has been used for making of biodegradable PVP and Cornstarch blend polymer electrolytes. Ion dynamics in polymer film membranes has been understood by conductivity and dielectric studies. The combination of 60wt% PVA and 40wt% Corn Starch is having the high conductivity value of 1.56 x 10-9 S cm-1 at ambient temperature and when the temperature increases, the conductivity also linearly increases to obtain 4.93 x 10-9 S cm-1 at 363 K which due to ion hopping mechanism in the polymer matrix. The frequency dependence of dielectric permittivity, dissipation factor (tangent loss) and electrical modulus have been used to know about dielectric behaviours of the polymer blend electrolytes. In dielectric studies, Non-Debye behaviour was observed in all samples.

Evaluation of the Rheological Property of Binder-Filler Systems after Oxidation Based on a Simple Film Oven Aging Method

Asphalt mastic is a combination of binder and filler. The binder-filler system within asphalt mixtures plays an important role in adhesion between mineral aggregates. The aging of binders in pavement always happens with fillers inside or contact with mineral aggregates, so it is critical to investigate the evolved rheological property of binder-filler systems during oxidative aging. In this study, simple film oven aging methods for the aging of mastics (binder-filler system) were conducted and verified by comparing the master-curves of aged mastics at different oven positions or different aging times. The frequency sweep test was performed to measure the changing stiffness of mastics with a different combination of binders and filler contents. Test results show that oven positions could influence the aging effect of the mastics significantly, given the influence of circulation. With increasing aging times, the complex modulus increases while phase angle decreases. Comparing the mastics which were first aged then mixed with mastics which were first mixed then aged, it was observed that fillers inside the binder could accelerate aging of the mastics. Additionally, the aging index of mastics with different combinations showed that both the modification of binders and filler contents could affect the aging rate of the mastics.

Numerical Investigation on Cooling Air Flow and Resistance Characteristics Inner Laminated Cooling Structures

Today, laminated cooling structures have been widely used in the designs of advanced gas turbines, because the structures with double walls, pins, impingement holes and film holes can provide much higher overall cooling effectiveness than simple film cooling. Of course, this kind of cooling structures also leads to a higher price due to a larger flow resistance to cooling air injection in comparison with the simple film cooling. The previous investigations concerned with the laminated cooling structures mainly focused on heat transfer performances, the flow resistance characteristics within the complex channel of the structures are relatively less. This paper presents a numerical investigation on the characteristics of the cooling air resistance passing through 6 different laminated structures. The influence factors on the fluid flow and resistance performances of cooling air, such as array, density and shape of film hole, as well as impingement-hole area (diameter), are discussed and compared at the same pressure ratios of the inlet to outlet of the 6 laminated structures. The discussions and comparisons reveal the following interesting phenomena: 1) A larger diameter of impingement hole corresponds to a larger mass flow rate of cooling air at the inlet of the laminated structure, but the inlet velocity is mainly dependent on the density of film hole. At the same total area of film holes, a larger density corresponds to a higher inlet velocity. 2) The flow rate through film hole of laminated structures is influenced more and more obvious by the outlet shape and the inflow angle of film hole as the increasing pressure ratio. 3) The resistance coefficients of the entire laminated structures are dependent on the density and shape of film holes. At the same total area of film holes, a higher density corresponds to a lower resistance coefficient. Although fan-shaped film hole can provide a larger cooling air coverage, the price is a higher resistance coefficient. Therefore, the applications of fan-shaped film holes in the laminated structures should be considered only in the regions with low environment pressures.

An Experimental Investigation on the Overall Cooling Performances of Two Turbine End-Wall Structures

This paper presents an experimental investigation on the overall cooling performances of two endwall specimens, one is a simple film cooling, the other is a laminated structure with pin-fins and impingement holes, but has the same cover board of the simple film cooling endwall. The two specimens are made of stainless steel with a real size of a gas turbine endwall. The experiments were carried out in a large temperature ratio (TR) of mainstream to cooling air (TR = 2.47), which is close to real operation conditions of modern gas turbines. The surface temperatures were measured by an infrared thermal imaging system (ITIS) at three blowing ratios (BRs = 0.63, 1.02, 2.04). The overall effectiveness of the two specimens was analyzed and compared. Through the analysis and comparisons, some interesting phenomena are discovered: 1) In general, as like as the previous studies of endwall cooling, the laminated endwall specimen can provide a higher cooling effectiveness averaged over the entire area than the simple film cooling specimen; 2) However, if we want to get more exact designs, the combination of the two structures may be better. Because of at low BR = 0.63, the simple endwall specimen can locally demonstrate a better cooling effect in an elliptic region of the endwall; 3) At high BR = 2.04, the design strategy of the simple endwall specimen can also locally be used in a triangle region. The exact designs can not only increase overall cooling effect, but also reduce the weight of whole endwalls.