Johannes Tesse Bastiaan Overvelde

Soft fluidic machines increasingly rely on self‐sustained oscillations to accomplish tasks autonomously without electronics or software. Typically, these oscillations arise from mechanical nonlinearities in complex geometries or relatively involved fluidic circuitry, and are passive in that they require external power sources. Here, we show that, by harnessing the coupling with a catalytic reaction, active oscillations can arise even in flat elastic membranes without fluidic circuits or external power. We embed a silver catalyst in a flat elastic membrane suspended over a pool of liquid hydrogen peroxide as fuel. When the fuel contacts the catalyst, it decomposes, releasing gases and generating pressure. We observe an oscillation where the reaction activates and deactivates spontaneously, causing the membrane to cyclically inflate and deflate for hours consecutively. Using experiments and a lumped‐parameter model, we show that the oscillation arises from an interplay between catalyst capillarity, membrane stiffness, and venting resistance, which together induce negative feedback and separation of timescales. These results demonstrate an active oscillation in which the energy release is directly coupled to the oscillation dynamics. By embodying energy within the oscillation, we expand the library of phenomena to achieve self‐oscillation in autonomous soft machines, opening avenues for elasto‐chemical strategies for physical control.

As soft robotics gains popularity, novel toolkits and educational systems for soft robotics are emerging. These endeavors focus mainly on teaching the programming or fabrication of soft robots, actuators, and sensors. However, as soft robotics moves toward electronics- and software-free control, it becomes essential to gain hands-on experience in soft fluidic circuit building and physical control. We bridge this gap in the educational landscape through the Soft Circuits Toolkit, a modular system of completely soft components that enables the creation and teaching of fluidic circuits, representing fluidic analogies of components such as resistors, capacitors, diodes, and transistors. The toolkit went through two design iterations and four user tests, which ultimately resulted in the toolkit presented in this article, consisting of 17 component types, a manual, and a companion website. User testing across various dimensions, including user experience, with technical university students ( N = 25) indicates that our toolkit is engaging, easy to learn, and promotes problem-solving behaviors. Based on these results, we believe that our kit can support technical universities in teaching about fluidic circuit building and physical control of soft robotics. All fabrication files for this toolkit have been made available open source.

Energy autonomy remains elusive in soft robotic devices, yet is essential for real-world operation beyond laboratory environments. Existing onboard energy-source strategies for air-powered soft robots require manual intervention for long-term use. We propose a thermopneumatic strategy that exploits circadian thermal oscillations and a pneumatic control circuit to enable energy autonomy in soft robotic systems. Our thermodynamic cycle harvests environmental thermal energy, stores it as pneumatic pressure, and autonomously discharges it to power soft pneumatic devices. Using a low-boiling-point fluid, our design repeatedly generates sufficient energy for pneumatic soft robots. Our model indicates this strategy is applicable worldwide under sufficient light intensity and ambient temperature. In a single real-world thermal cycle, our design triggered 142 activations of a self-oscillating actuator, while a two-limbed soft pneumatic robot harvested thermal energy to achieve locomotion. This study presents a long-term energy-harvesting strategy enabling energy autonomy in electronic-free soft robots without repeated manual intervention.

Soft robots harness their built‐in mechanical intelligence to respond directly to their environment. However, they typically still depend on predefined sequences to coordinate their limbs, and external centralized hardware is often used for coordination in changing circumstances. In contrast, in nature, invertebrates like echinoderms distribute behavioral control throughout their body. Inspired by this decentralized computation strategy, we present a modular soft robotic system in which each limb independently adjusts the timing of its actuation to achieve phototaxis via entirely local, stochastic feedback with limited memory. Through this embodied computation approach, coordination emerges from the interaction of the body and the environment. We show robust phototaxis for soft robots that have different morphologies, that undergo damage, and that exhibit highly nonlinear leg behavior, all without an internal body representation. These results, therefore, offer a blueprint for designing resilient, autonomous soft robots that exploit the potential intelligence of their soft adaptive bodies.

Fluidic circuits have shown significant promise in enabling complex functionality in soft robots with a minimal number of input signals. However, implementing complex behaviors typically involves numerous specialized components, resulting in intricate and nonversatile circuits. To address this challenge, a multifunctional fluidic unit designed to operate flexibly as a valve, sensor, or actuator is introduced. This unit provides an extensive design space that allows precise tuning to achieve the desired functionality. In particular, one configuration integrates all three functions simultaneously, resulting in a self‐sensing oscillating actuator. By assembling multiple units—each customized for specific roles—complex robotic behaviors can be realized. The versatility and effectiveness of this modular approach are demonstrated by creating several robotic systems, including a controlled shaker, a multimodal hopper, and a crawler capable of sensing environmental boundaries. Furthermore, when these units are mechanically coupled via a shared body, it exhibit emergent passive behaviors, such as self‐synchronization—a behavior that is elucidated with a Kuramoto model of networks of oscillators. This study highlights the potential of multifunctionality as a powerful and efficient strategy for realizing embodied intelligence in fluidic robotic systems.

Cardiovascular diseases are a leading cause of mortality, with limited possibilities for transplantation due to a critical shortage of donor hearts. Replacing the heart with total artificial hearts (TAHs) remains challenging, due to size constraints and energy requirements, among others. To address this, we introduce the LIMO heart, a compact TAH concept based on an efficient soft fluidic transmission system. By reducing actuator volume and enhancing energy transfer, LIMO enables a more compact and efficient design. We developed a soft ventricle prototype using thin-walled pouch actuators that achieve transmission ratios above one via circumferential shrinkage. A fast, cost-effective prototyping method accelerated testing. Experimental results showed high energy transfer efficiency (82 to 91%), and in vitro tests demonstrated promising cardiac outputs of 5.9 liters per minute against aortic pressure and 7.6 liters per minute against pulmonary pressure. These findings represent a step toward a more broadly applicable biventricular soft robotic TAH for treating end-stage heart failure.

End-stage heart failure is a deadly disease. Current total artificial hearts (TAHs) carry high mortality and morbidity and offer low quality of life. To overcome current biocompatibility issues, we propose the concept of a soft robotic, hybrid (pumping power comes from soft robotics, innerlining from the patient’s own cells) TAH. The device features a pneumatically driven actuator (septum) between two ventricles and is coated with supramolecular polymeric materials to promote anti-thrombotic and tissue engineering properties. In vitro, the Hybrid Heart pumps 5.7 L/min and mimics the native heart’s adaptive function. Proof-of-concept studies in rats and an acute goat model demonstrate the Hybrid Heart’s potential for clinical use and improved biocompatibility. This paper presents the first proof-of-concept of a soft, biocompatible TAH by providing a platform using soft robotics and tissue engineering to create new horizons in heart failure and transplantation medicine.