Design and manufacture of edible microfluidic logic gates

Edible robotics is an emerging research field with potential use in environmental, food, and medical scenarios. In this context, the design of edible control circuits could increase the behavioral complexity of edible robots and reduce their dependence on inedible components. Here we describe a method to design and manufacture edible control circuits based on microfluidic logic gates. We focus on the choice of materials and fabrication procedure to produce edible logic gates based on recently available soft microfluidic logic. We validate the proposed design with the production of a functional NOT gate and suggest further research avenues for scaling up the method to more complex circuits.Comment: 7 pages, 6 figure

Towards edible drones for rescue missions: design and flight of nutritional wings

Drones have shown to be useful aerial vehicles for unmanned transport missions such as food and medical supply delivery. This can be leveraged to deliver life-saving nutrition and medicine for people in emergency situations. However, commercial drones can generally only carry 10 % - 30 % of their own mass as payload, which limits the amount of food delivery in a single flight. One novel solution to noticeably increase the food-carrying ratio of a drone, is recreating some structures of a drone, such as the wings, with edible materials. We thus propose a drone, which is no longer only a food transporting aircraft, but itself is partially edible, increasing its food-carrying mass ratio to 50 %, owing to its edible wings. Furthermore, should the edible drone be left behind in the environment after performing its task in an emergency situation, it will be more biodegradable than its non-edible counterpart, leaving less waste in the environment. Here we describe the choice of materials and scalable design of edible wings, and validate the method in a flight-capable prototype that can provide 300 kcal and carry a payload of 80 g of water

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Department of Mechanical Engineeringope

Compliant mechanosensory composite (CMC): a compliant mechanism with an embedded sensing ability based on electric contact resistance

Sensing ability enables a robot to be aware at its motion, or to modulate the locomotory behavior. While many sensing components have been developed for macroscale robots, such off-the-shelf sensors are hardly integrated with millimeter-to-centimeter scaled robots due to the size limitation. In this work, we propose a compliant mechanosensory composite (CMC) to fabricate a small compliant mechanism with an embedded sensing ability. For this purpose, a conductive polymer PEDOT:PSS was directly printed onto the two layers of flexural joints in a compliant mechanism. Owing to the variation of electric contact resistance upon bending, the CMC could measure the bending angle of the flexural joint. Three different sensor pattern topologies (e.g. planar, interdigitated, and serpentine) were tested, and the serpentine pattern was chosen. Also, its performance was further verified by analyzing the cyclic bending and transient response. Overall, a sparsely printed serpentine pattern with thicker line exhibited consistent response without a noticeable hysteresis. To demonstrate the applicability of the CMC, a small inchworm robot actuated by a micro servo motor was built, and its motion was successfully measured using the embedded sensor. In addition, multi degrees-of-freedoms mechanisms such as a four-bar spherical joint was fabricated to measure a three-dimensional motion. We expect the proposed CMC will enable a small robot to become sensible at its self motion, external load, and physical contacts in future

Development of a Four-Bar Linkage Integrated with a Polypyrrole Actuator and a Resistive Sensor Toward Biomimetic Pleopods

Developing a highly integrated mesoscale (a few millimeter-centimeter) mechanism is dauntingly challenging work, and yet many technological improvements in soft robotics keep pushing the boundary. In this work, we proposed a new approach to develop a compliant mechanism integrated with a conductive polymer actuator and a resistive sensor. A polypyrrole (PPy) was utilized to fabricate a unimorph bending actuator through electropolymerization owing to its low operating voltage and high energy density. Also, carbon blacked filled polydimethylsiloxane (CPDMS) was directly contact printed on a flexural joint of a compliant mechanism to sense its motion. The performance of a PPy actuator and CPDMS sensor were individually investigated, which would be valuable at followup studies. In addition, inspired by pleopods (i.e. swimming legs) of aquatic arthropods, a CPDMS sensor integrated four-bar-linkage driven by a PPy actuator was developed for future applications in mesoscale swimming robots. After immersing in an electrolyte solution, the PPy actuator successfully drove the linkage structure with 5 V while the CPDMS sensor was able to partially sense the motion

Design of hair-like appendages and their coordination inspired by water beetles for steady swimming on the water surface

Locomotion of water beetles have been widely studied in biology owing to their remarkable swimming skills. Here, we investigated the coordination between the two pairs of legs to achieve steady swimming with novel hair-like appendages. Some design considerations and a fabrication of the hair-like appendages, which can passively adjust their projected area to obtain net thrust, are proposed. As do water beetles in nature, the coordination between the two pairs of legs were considered to achieve steady swimming without jerky motion by varying the beating frequency and phase of the legs. To verify the functionality of the hair-like appendages and their coordinations, six different types of appendages were fabricated, and two robots (one with single pair and the other with two pairs of legs) were built. Locomotion of the robots were compared through experiments, and steady swimming was achievable by properly coordinating the two-pairs of legs without sacrificing the swmming speed

Toward Fast and Efficient Mobility in Aquatic Environment: A Robot with Compliant Swimming Appendages Inspired by a Water Beetle

Water beetles are proficient drag-powered swimmers, with oar-like legs. Inspired by this mechanism, here we propose a miniature robot, with mobility provided by a pair of legs with swimming appendages. The robot has optimized linkage structure to maximize the stroke angle, which is actuated by a single DC motor with a series of gears and a spring. A simplified swimming appendage model is proposed to calculate the deflection due to the applied drag force, and is compared with simulated data using COMSOL Multiphysics. Also, the swimming appendages are optimized by considering their locations on the legs using two fitness functions, and six different configurations are selected. We investigate the performance of the robot with various types of appendage using a high-speed camera, and motion capture cameras. The robot with the proposed configuration exhibits fast and efficient movement compared with other robots. In addition, the locomotion of the robot is analyzed by considering its dynamics, and compared with that of a water boatman (Corixidae).clos

Design and Analysis of a Rotational Leg-type Miniature Robot with an Actuated Middle Joint and a Tail (RoMiRAMT-II)

In this paper, a rotational leg-type miniature robot with a bioinspired actuated middle joint and a tail is proposed for stable locomotion and improved climbing ability. The robot has four independently actuated rotational legs, giving it advantages of both wheel-type and leg-type locomotion. The design parameters of the rotational legs were determined by 3D simulation within the seven candidates that selected by a newly proposed metric. It also has unique characteristics inspired by biological structures: a middle joint and a tail. An actuated middle joint allows the frontal body to be lifted or lowered, which was inspired by a flexible body joint of animals, to climb higher obstacles. Effectiveness of the middle joint was analytically verified by the geometric analysis of the robot. Additionally, a multi-functional one Degree Of Freedom (1-DOF) tail was added; the tail prevented the body being easily flipped, while allowed the robot to climb higher obstacles. A bristle-inspired micro structure was attached to the tail to enhance straightness of locomotion. Body size of the robot was 158 mm x 80 mm x 85 mm and weighed 581 g including a 7.4 V Li-Polymer battery. The average velocity of the robot was 2.74 m.s(-1) (17.67 body lengths per second) and the maximum height of an obstacle that the robot could climb was 106 mm (2.5 times of leg length), which all were verified by experiments

Design and Analysis of a Rotational Leg-type Miniature Robot with and Actuated Middle Joint and a Tail (RoMiRAMT)

In this paper, a rotational leg-type miniature robot with an actuated middle joint and tail, called RoMiRAMT, is proposed for stable locomotion and improved climbing ability. The robot has four independently actuated rotational legs, giving it advantages of both wheel-type and leg-type locomotion. The design parameters of the rotational legs were determined by 3D simulation within the properly selected candidates. It also has unique characteristics inspired by biological structures: a spine and a tail. An actuated middle joint allows the frontal body to be lifted or lowered, which was inspired by a spine, to climb higher obstacles. Additionally, a multi-functional two degrees of freedom (2-DOF) tail was added; the tail provides instant deceleration, and minimized the likelihood of flipping, while allowing the robot to climb higher obstacles. A microcontroller was embedded in the robot, along with a micro-camera and an inertia measurement unit (IMU) sensor. By controlling the robot using the yaw angle signal measured by the IMU sensor, straight movement was enhanced. The body size of the RoMiRAMT is 155 ⨉ 80 mm without the rotational legs, and the weight is 593 g including batteries. The maximum velocity of the robot was 2.58 m/s (16.65 body lengths per second) and the maximum height of an obstacle that the robot can climb was 95 mm, which all were verified by experiments

Integrated Design and Fabrication of a Conductive PDMS Sensor and Polypyrrole Actuator Composite

Polypyrrole (PPy) has been widely used as an electro active polymer actuator owing to its high energy density, and the applicability in low voltage (i.e. less than 3 V) driven systems. Its scalable fabrication process also enables a PPy actuator to be used in mesoscale (a few millimeter to centimeter) robotic mechanisms. Although many PPy actuator driven mechanisms have been studied previously, its in-situ measurement of the motion of a PPy actuator was rarely investigated. To further expand the potential applications of a PPy actuator in automation and control of mesoscale robots, it is essential to develop a highly integrated sensor-actuator structure. In this work, we proposed a new fabrication process to make one kind by electrochemically synthesize a PPy layer on the opposite side of a carbon doped polydimethylsiloxane (CPDMS) based resistive sensor where a polyvinylidene fluoride (PVDF) membrane was used as a common substrate. A simple way to make a CPDMS sensor was proposed, and its electric and mechanical properties were studied using various material combinations. In addition, the characteristics of a CPDMS-PPy composite was studied using cyclic voltammetry, and the integrated sensor response analysis with and without applied load during the electrochemically induced PPy actuation. The proposed structure was not only able to sense its bending motion, but it could also roughly distinguish the stiffness of an object in contact. To demonstrate a simple application, a compliant linkage structure, which simultaneously actuated and sensed by the proposed composite, was built