Underwater Suit-Wearing Cyborg Insect Capable of Hours-Long Diving and Terra-Aqua Travel

IntroductionCyborg insects are hybrid systems that integrate living insects with electronic components1,2,3,4,5, combining the biological capabilities of insects with the technological functions of electromechanical devices to remotely induce their movements. Current cyborg insects are envisioned for use in complex tasks such as search-and-rescue missions6, pipeline inspection7 and object transportation8, with cockroach-based ones considered the most promising owing to their robustness and ease of locomotion control. Unlike conventional artificial small robots which consume substantial power to drive actuators, draining the energy stored in their onboard batteries, cyborg insects locomote with the insects’ own muscles, requiring no electrical actuation and achieving minimal power consumption9,10. Their compact size, adaptability, and robustness allow them to traverse cluttered environments and enter into confined spaces inaccessible to larger robots11.However, their operation is constrained by the host’s physiological requirements, such as optimal oxygen and temperature levels. Naturally, the inability of terrestrial hosts like cockroaches to absorb aquatic oxygen prevents underwater functions12. Given that real-world search-and-rescue or infrastructure inspection terrains often include puddles, flooded zones, or other partially submerged areas, continuous operation requires developing cyborg insects capable of temporary submersion and locomotion underwater while maintaining normal metabolic activity.If a miniature unit capable of supplying oxygen could be mounted onto a cockroach’s body, it might be possible to realise a cyborg cockroach that operates both on land and underwater. Cockroaches, like most terrestrial insects, breathe through thoracic spiracles that take in oxygen directly from the air13,14. If oxygen could be supplied to these spiracles while preventing water entry, cyborg insects might be able to operate underwater as well as on land. To realise this concept, we designed a compact and self-contained oxygen supply system, referred to as a ‘diving suit’, based on a controlled chemical reaction that gradually releases oxygen without requiring electronic components. Utilising the Madagascar hissing cockroach (Gromphadorhina portentosa) as the biological platform, a wearable diving suit comprising a flexible shell, an oxygen generator and oxygen delivery tubes was designed enabling survival and task execution during prolonged submersion (Fig. 1A). The flexible abdominal shell insulates the abdominal spiracles from surrounding water and acts as an oxygen storage and transport tank (Fig.

1B, i). The oxygen generator is a sealed chamber containing a hydrogen peroxide (H2O2) solution and a manganese dioxide (MnO2) catalyst. Under catalytic action, the H2O2 decomposes to produce oxygen (Fig. 1B, ii) to maintain the insects’ normal respiratory function. The oxygen delivery tubes connect the flexible shell to the cockroach’s thoracic spiracles (Fig. 1B, iii), transporting the generated oxygen to the tracheae. Together, these components enable cockroaches to achieve amphibious locomotion (Fig. 1C). This study presents an amphibious cyborg insect capable of user-induced locomotion with a low-power, compact design, that enables long-duration operation in confined and cluttered terrestrial–aquatic environments.Fig. 1: Concept and design of amphibious cyborg insect system.A Conceptual illustration of the cyborg insect operating underwater. B Structural design and oxygen generation mechanism of diving suit for cyborg cockroaches. i) Diving suit comprises a flexible waterproof shell, an integrated oxygen generator and oxygen delivery tubes. ii) Oxygen generator employs a MnO2-H2O2 catalytic reaction on a cellulose sponge and generates oxygen and water. iii) Generated oxygen is delivered to the prothoracic and mesothoracic spiracles through oxygen delivery tubes. C Demonstration of real-world locomotion. Photographs of the cyborg insect with a diving suit performing i) downward climbing, ii) underwater locomotion, and iii) upward climbing.Results and discussionIntegrative design of diving suit for underwater survival and mobilityA chemical reactor-based oxygen generation unit (Fig. 2A, i), was implemented to eliminate the need for electronic components and maintain a compact, insect-mountable design. This oxygen generator unit is housed within a lightweight and flexible shell that attaches easily to the insect’s body (Fig. 2A, ii). Given that cockroaches breathe via thoracic spiracles14, oxygen delivery tubes were installed to connect the generated oxygen to the thoracic spiracles (Fig. 2A, iii). The tube tips were shaped for secure mechanical attachment to the spiracular valves, forming an integrated and wearable diving suit.Fig. 2: Structure and oxygen delivery mechanism of diving-suit system.A Diving suit integrates i) an oxygen generator, ii) a flexible waterproof shell and iii) oxygen delivery tubes.

The generated oxygen is delivered through tubes to the thoracic spiracles via spiracle connectors, forming a sealed respiratory pathway. B Oxygen generator design. i) Exploded view of oxygen generator. It includes: a container with a MnO2-deposited cellulose sponge inside, a sealing lid, and a hydrophobic PTFE microporous membrane. ii) Working principle of hydrophobic PTFE microporous membrane, which allows gas to pass through while preventing liquid penetration. C Optical microscope image of thoracic spiracles. The left one is the prothoracic spiracle, which remains open with a lip-like structure. The right one is the mesothoracic spiracle, which stays closed with only a small hole open. D Customised spiracle connectors with oxygen delivery tubes. E Installation of the oxygen delivery tube with spiracle connector to i–ii) prothoracic spiracle, iii–iv) mesothoracic spiracle.Oxygen was generated through the MnO2-catalysed decomposition of H2O2, which produces only water and oxygen as by-products and proceeds readily under neutral conditions15,16,17. When MnO2 powder was directly mixed with H2O2 solution in the confined 1.6 ml reactor caused rapid decomposition, vigorous bubbling and fluid agitation15,18, which destabilised the cockroach’s movement. Hence, MnO2 was deposited onto a highly absorbent hydrophilic cellulose sponge (1 × 1 cm). This configuration confined the reaction to solid–liquid interfaces, where oxygen was generated from numerous separated microsites (Supplementary Fig. S1), preventing gas accumulation and large-bubble coalescence. To prevent liquid agitation and ensure stable oxygen release, H2O2 was dripped onto the sponge, which serves as a carrier for the H2O2 solution and a substrate for MnO2 deposition. To ensure the safe operation of oxygen generators near insects, the generator structure must prevent chemical leakage and transport only oxygen to the outside shell. The oxygen generator comprises the small container that housed MnO2-deposited sponge and a lid that incorporated hydrophobic PTFE microporous membrane with a pore size of 0.22 µm (Fig. 2B, i). The micropores allow gas to permeate but block liquid penetration.

The membrane was integrated into the lid, allowing the gaseous oxygen alone pass through and be released outside while remaining H2O2 solution, MnO2 powder (mostly 1–10 µm in diameter, larger than the pore size), and the generated liquid water were retained inside the generator, eliminating risk of chemical leakage (Fig. 2B, ii). Sealing stability of the oxygen generator was confirmed by subjecting the assembled unit to agitation on a vortex shaker for 10 min to simulate mechanical shocks. Afterward, the lid surface was wiped with water-sensitive test paper, and no colour change was observed. That unit was then placed with the lid and membrane facing downward over another piece of water-sensitive test paper for 3 h. No colour change was detected on the paper, confirming that no liquid leakage occurred. To further evaluate potential biological impact on long-term exposure to byproducts of H2O2 decomposition, five diving suit-wearing cyborg insects were monitored for three days following experimental exposure. All individuals survived throughout the observation period with normal behaviours. Because the decomposition of H2O2 is exothermic19, excessive heat could disturb the insect’s physiology. However, no noticeable temperature rise was detected at the oxygen generator when monitored with an infrared camera (Ti400, Fluke), with the temperature remaining between 23.6 and 24.0 °C throughout the reaction (Supplementary Fig. S2). This result suggested that the dispersed MnO2 catalytic sites on the cellulose sponge and the utilisation of small reactant amounts (2 mg MnO2 powder and 3% H2O2 solution) minimised the heat release, prevented localised heat accumulation and allowed the generated heat to diffuse without affecting the surrounding temperature. Future improvements in oxygen generators could focus on actively regulating oxygen generation rates. For example, integrating miniature oxygen concentration sensors and micropumps would enable quantitative delivery of H2O2 based on real-time oxygen levels within the suit, thereby achieving dynamic oxygen supply matched to the insect’s activity states and overcoming limitations of the current passive system.Initially, dorsal mounting of the oxygen generator on the cockroach created significant water-resistance during underwater locomotion and raised the centre of gravity to approximately 1.7 cm, causing postural instability and rollover. The ventral side provided only a limited gap of 2–3 mm from the ground, insufficient to accommodate the oxygen generator there.

To preserve the insect’s streamlined body profile and maintain a low centre of gravity, the generator was therefore positioned at the posterior end of the abdomen and secured by enclosing both the generator and the abdomen within the lightweight and flexible shell (Fig. 2A, i). This configuration enabled stable and smooth underwater walking without rollover.The shell was designed as a thin-walled (1 mm), flexible enclosure that wraps around the cockroach’s abdomen, enabling fabrication with flexible resin, preserving natural movement, and accommodating individuals with slight size variations (Fig. 2A, ii). The shell geometry was modelled on the natural morphology of the cockroach’s abdomen, incorporating an oval cone shell led to the least impact on the cockroach’s movement20 and maintained the streamlined body form of the cockroach. The cone’s wide opening allowed the shell to slide smoothly over the tapered abdomen from the posterior end, making the installation straightforward. The anterior end of the shell was sealed to the cockroach’s first abdominal segment with a soft nitrile rubber membrane (0.16 mm thick, 1.0 cm wide). The membrane filled the narrow gap between the shell and the exoskeleton surface, forming an elastic seal that prevented water ingress and maintained a watertight interface. Its flexibility allowed the membrane both to accommodate slight variations in abdominal size among individuals and to deform with the cockroach’s body during locomotion (Supplementary Fig. S3), thereby preserving natural vertical and lateral movement.The oxygen delivery tubes transport oxygen from the oxygen generator inside the shell to the thoracic spiracles (Fig. 2A, iii). One end of the tubes connects to the shell; the other end connects to the spiracles. The external, soft and anatomically distinct nature of the two pairs of thoracic spiracles (Fig. 2C) presents a design challenge14. The prothoracic spiracles remain open, forming a groove that directly exposes the spiracular valve, whereas the mesothoracic spiracles remain closed, leaving only a small hole visible. This complexity mandated the design of customised connectors to achieve a tight seal that ensures both effective oxygen delivery and waterproof sealing. The prothoracic spiracles connector has a spoon-shaped cover with an oval cap (Fig. 2D, i), designed to fully enclose the spiracular valve exposed at the prothoracic spiracle (Fig.