Navigating the body’s smallest, tightest pathways has long restricted the reach of minimally invasive surgery. Traditional instruments struggle to access tunnels narrower than a grain of rice, limiting image quality and therapeutic precision. Soft robots are promising alternatives, but creating stable, fluid-powered devices only a few millimeters wide has remained a major engineering challenge. A new development process now enables the reliable construction of these tiny robots, allowing for delicate airway navigation and future in-body sensing and treatment.

Researchers at Shanghai Jiao Tong University (Shanghai, China) have developed a dexterous, noodle-thin soft robotic scope that is capable of advancing deep into the airway, steering left, right, and downward to image or manipulate tissue in tight anatomical spaces. To develop the soft robot, the researchers used a modified version of traditional “bubble casting,” a method where a long bubble is injected into liquid silicone to form a hollow channel as the material cures.

In conventional casting, miniaturization often fails because surface tension tears fragile bubbles apart, resulting in collapsed or uneven inner walls. To overcome this, the researchers engineered a highly stable silicone mixture. By adding a thickener and an accelerator, the silicone behaves like chilled toothpaste—soft and flowable when injected but instantly stiff upon air contact. This allows bubbles to pass cleanly through the mixture, forming smooth, precise inner voids that define the soft robot’s tiny, functional channels.

Results from early demonstrations, published in National Science Review, show the robot maneuvering through airway passages just a few millimeters wide to collect high-resolution images or remove clots. The refined bubble casting technique ensures each miniature segment has consistent structure and mechanical properties, essential for accurate actuation.

The next stage of development will focus on embedding sensors capable of measuring temperature, pressure, and pH within the robot’s body, as well as adding hydrogel-based drug coatings that dissolve on command. These upgrades would enable Soft Robot 2.0—smart, non-invasive “in-body pharmacies” designed to monitor tissue and deliver therapeutic compounds precisely where they are needed.

“We aren’t just making robots smaller—we’re making surgery gentler too,” said Guoying Gu, corresponding author of the study.

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