One of the issues in the field of soft-robotic systems is that how to create a fast displacement mechanism which it operates close to nature. This paper presents a deep study of hybrid of mixed electrolysis and fluids chemical reaction (HEFR) method for general applications, considering contraction/expansion of a single/multiple (taped) soft bio-inspired actuators in various conditions and a practical instance of a moving wing mechanism. This research extends the recent study of corresponding author’s team (Zakeri and Zakeri, Deformable airfoil using hybrid of mixed integration electrolysis and fluids chemical reaction (HEFR) artificial muscle technique. Sci Rep 11:5497, 2021) that previous study concentrated on just single bio actuator in deformable airfoil. This work offers a general artificial muscle which it employs the hybrid of mixed electrolysis (electrolysis module with 10 mL capacity without any separation of materials such as O2 or H2), two fluids for chemical reaction (sodium bicarbonate (NaHCO3 (s)) and acetic acid (CH3COOH (l))) and also multilayer soft skin bags (40 × 30 mm). The analyzed parameters are amount of displacement (contraction/expansion) over time (response time), the ratio of output force to total weight and extremely low expense of manufacturing. The main results are as follows: the released energy from 1 mL sodium bicarbonate, 10 mL acetic acid and a 12 V electrolysis module have ability to give a response time less than 1 s (25 mm expansion and 4 mm contraction) with 12 W power consumption and also bio actuator can easily displace a 250 g object (total weight of components is almost 33 g). Also, it has been shown that the response time of mixed electrolysis in the proposed inactive solution (without any fresh chemical reaction) will be nine times to pure water. In the active solution (refresh chemical reaction), response time of HEFR will be accelerated 2.44 times to pure chemical reaction. By applying the multilayer soft skin bags or soft actuators (multi contraction and multi expansion model), a practical movable flapping wing has been presented which a full cycle of flapping would take 2 s. The proposed method has ability to show a quick response time, without making any noise, very low construction cost and practical for general and frequent uses.

In this research, by inspiration of natural myosin motion in artificial muscle contraction, a new method for changing the thickness of an airfoil has been proposed by hybrid of mixed integration electrolysis module and chemical reaction (HEFR) of sodium bicarbonate (NaHCO3 (s)) and acetic acid (CH3COOH (l)). The mentioned method has the ability to create pressure in the fluid in a short time and fast transfer without delay due to the integration of the method in the fluid transfer tube to soft sealed skin. With soft sealed skin swelling and movement of solid skeletal structure, the force is transmitted to the desired mechanism. First, for a single of soft skin and solid structure, remarkable displacement over time in the various loading condition (by the inflation tester) has been investigated. It is shown that the proposed mechanism is capable of moving 246 g during 3 s with total mechanism weight of 10 g. In the following, the mechanism is developed into a symmetrical rhombus (set of soft skin-solid structure) with the ability to contract and expand to provide variable airfoil thickness. The proposed mechanism has the ability to move in the horizontal and vertical axis (expansion and contraction) in lower than 5 s by applying the HEFR technique. Such a mechanism is mounted on a symmetrical airfoil and has the ability to change the airfoil thickness with the appropriate response time. The proposed mechanism can be used in various industrial applications such as robotics.