I. Current Technical Challenges Facing the Industry

Traditional robots rely on rigid structures to function, whereas soft robots draw inspiration from biological bodies and their movement principles, with designs entirely based on flexible materials.

The morphology of a soft robot directly determines its locomotion performance: actuators generate motion by inflating and deflating internal chambers of varying sizes and shapes. Consequently, to achieve the desired motion, it is essential to master the design principles of soft robots and thoroughly understand the deformation characteristics of their constituent materials.

Among numerous materials, silicone rubber is ideally suited for fabricating compliant grippers, as it can undergo deformation under low loads while exhibiting both high elasticity and excellent fatigue resistance.

Silicone 3D printing lowers the barrier to development, serving as a powerful enabler of innovation. It streamlines the design process and plays a pivotal role in advancing soft robotics. This technology is particularly well-suited for fabricating prototypes and intricate components, offering distinct advantages in customization, production efficiency, and cost control. Take soft grippers as an example: researchers can rapidly modify cavity shapes and finger structures without repeatedly tooling molds, enabling multiple rounds of prototype iteration.

II. Capability for Implementing Geometric Structures

The grasping performance of a soft gripper is highly dependent on the geometric configuration of its internal air chambers and flow channels, with the wall‑thickness distribution and arrangement of the finger chambers directly determining the bending posture after inflation. Leveraging silicone 3D printing enables the fabrication of highly complex silicone structures that are difficult to achieve using conventional injection‑molding or casting processes, making it ideally suited for producing intricately shaped components such as nested structures and hollow‑core designs.

3D printing enables the monolithic fabrication of pneumatic or hydraulic soft‑gripper actuators featuring hollow chambers and intricate fluidic channels. Unlike conventional casting, which is limited to simple single‑chamber fingers, 3D printing allows for the integration of multiple independent cavities within a single gripper finger. Such actuators can be custom‑designed to meet the specific deformation requirements of soft robotic grippers. The geometry of the actuator’s chambers and the gradient design of their wall thickness determine the bending angle and curvature upon inflation, thereby enabling a wide range of motions—such as multi‑segmental, piecewise bending that mimics the jointed flexion of human fingers—thus enhancing grasping performance. Moreover, by leveraging soluble sacrificial support materials compatible with the printing system, it becomes possible to create internal structures—like overhanging features and sealed cavities—that are unattainable with traditional manufacturing techniques, freeing the design of soft grippers from the constraints imposed by conventional fabrication processes.

III. Environmental Adaptability

3D-printed silicone products exhibit excellent waterproof and airtight properties, enabling the reliable fabrication of sealed, flexible gripper actuators or gripper modules with multiple independent chambers capable of performing complex deformation motions. Airtightness directly determines the operational stability of pneumatic soft grippers, preventing gas leakage that could lead to insufficient gripping force and actuation failure.

It is also possible to combine multiple deformation modes. For example, a flexible gripper actuator can be designed to perform both extension and bending motions while simultaneously incorporating a small torsional twist. When grasping objects with circular or irregular shapes, the fingers can adaptively conform to the object’s surface, thereby enhancing the precision and versatility of the grasping task and reducing the requirements for object‑positioning accuracy.

By adjusting printing parameters such as layer height, material composition, and infill structure, the dynamic performance of soft‑robotic grippers can be tailored, including their deformation output force and response speed. For example, for the same gripper design, regions printed at a 0.3 mm layer height exhibit more compliant deformation, while those printed at 0.6 mm show greater stiffness, enabling a gradient in stiffness across a single gripper finger. Without requiring material changes, optimizing the gripper’s mechanical properties solely through parameter adjustments allows it to balance compliant deformation with structural support, making it suitable for handling objects of varying weights and fragilities.

IV. Multi-Material Integrated Manufacturing

3D printing enables one‑step fabrication of parts with fully integrated, multifunctional properties. By selecting raw materials with varying stiffnesses, it is possible to combine flexible and rigid regions within a single component—for example, pairing silicone with thermoplastic polymers or using silicones of different hardness grades. This tunable material stiffness facilitates the creation of robust, reliable mechanical joints between flexible grippers and mounting bases.

3D printing also enables the direct integration of pressure, strain, and tactile sensors into the soft‑robotic body during the printing process. This capability to fabricate multi-material soft robots with embedded sensors in a single step is of great significance for the development of intelligent human–robot interfaces, as it enhances the device’s environmental perception, motion accuracy, and adaptability to diverse environments.

Meanwhile, silicone 3D printing enables part performance to be tailored to real-world application requirements: high‑hardness silicone requires greater external force to deform but can deliver higher torque and stronger gripping force; softer silicone deforms more easily, making it less likely to damage fragile objects during handling, though it cannot withstand heavy loads.

V. Equipment Technical Principles and Operational Workflow

Equipment Technical Principle:

The Lynxter series 3D printers employ a liquid additive manufacturing (LAM) process. Liquid silicone rubber is supplied in two components, A and B, each delivered to a separate positive-displacement metering pump. The two components are mixed at the pump outlets and then extruded through a nozzle, with nozzle diameters ranging from 0.23 mm to 1.04 mm. The silicone material is deposited layer by layer in the form of tiny droplets until the complete part is formed.

The device is equipped with two independent print heads and can also extrude soluble sacrificial support material. This support material is used to fabricate complex structures with large overhangs, maintaining the overall shape of the part during the curing stage. Upon mixing components A and B, a chemical reaction is triggered, causing the liquid silicone rubber to transition into a solid state while simultaneously achieving all desired mechanical properties, including elasticity, hardness, chemical stability, and thermal stability.

Soft robotic flexible gripper fabrication process:

(1) 3D models can be created using any CAD software. Slicing software then generates printer‑compatible process parameters and outputs G‑code; simply import the file into the printer to begin manufacturing.

(2) Once the silicone material is extruded from the nozzle, it immediately undergoes a chemical reaction. The time required to form a part depends on its complexity, ranging from a few minutes to several hours. Curing can be accelerated by heating the print chamber or by baking the printed part in an oven after printing. Silicone parts require no additional post‑processing to achieve their intended performance.

VI. Relevant Cutting-Edge Application Cases

(1) Targeting Manufacturing and Industry 4.0: Flexible Gripping Reimagines Automated Operations

Silicone and 3D printing technologies are emerging as key drivers of innovation in modern manufacturing, reshaping the ways collaborative robots and automated systems are deployed. In electronics manufacturing, assembling precision components such as microchips demands highly delicate operations; conventional rigid robotic grippers can easily damage workpieces or fail to provide stable clamping. The food industry faces similar challenges: fruits and vegetables are soft and irregularly shaped, posing significant hurdles for traditional robots tasked with sorting and picking.

Pneumatic/hydraulic soft grippers incorporating compliant materials represent a viable solution, capable of conforming to the complex geometries of precision workpieces. These soft robots are driven by pneumatic or hydraulic actuation, offering controllable and gentle gripping forces; their inherent compliance allows them to adapt to irregular workpiece contours, ensuring secure grasping without causing damage. This approach is particularly well-suited for industries requiring delicate handling—such as food processing, textiles and apparel, sensitive pharmaceuticals and medical devices, and optical manufacturing—enabling the development of responsive flexible production lines, streamlining workflows, and fostering safer human–robot collaboration environments.

Fragile products like potato chips can be handled safely using soft robotic grippers.

(2) Soft-Robotics Innovation in Healthcare: Patient-Centric Flexible Medical Devices

Silicone‑based soft robots are bringing transformative changes to the medical field, ushering healthcare into a new, patient‑centered era. In the realm of prosthetics, 3D‑printed silicone soft robotic limbs offer exceptional adaptability and, by mimicking natural human movements, significantly enhance the quality of life for amputees. Moreover, the combination of silicone and 3D printing enables the customization of medical devices, improving both therapeutic outcomes and patient comfort.

Soft robotics holds tremendous promise in minimally invasive surgery (MIS) and robot-assisted minimally invasive surgery (RAMIS). Current robot‑assisted MIS systems are predominantly rigid, with limited maneuverability, making it difficult to access specific anatomical sites and posing a risk of tissue damage. By virtue of their morphological and structural flexibility, soft robots have the potential to address these challenges, enabling more precise and safer surgical procedures. Soft robotics is fundamentally transforming patient care, offering more personalized and efficient solutions across a wide range of medical workflows.

Soft prosthetic hand prototype from Rob Scharff’s soft robotics research project

(3) Silicone 3D Printing Empowers Soft Robotics Development: Streamlining Prototyping and the Fabrication of Complex Structures

Silicone‑based additive manufacturing is a key approach for fabricating soft‑robotic structures, offering advantages such as rapid prototyping and the ability to produce complex geometries that are difficult to achieve with conventional fabrication methods. 3D printing enables swift iterative design modifications, thereby shortening the development cycle of soft‑robotic systems; one of its core strengths lies in the high‑precision fabrication of customized, intricate components with variable wall thicknesses and internal cavities, meeting the unique design requirements of soft robotics.

The 3D‑printed soft gripper developed by Lynxter—available in both pneumatic‑actuated and non‑pneumatic versions—is a prime example. Similar technologies are also employed to fabricate flexible grippers, actuators, and wearable assistive devices, enhancing device functionality and adaptability. The convergence of silicone, 3D printing, and soft robotics has given rise to innovative technological solutions, continually expanding the frontiers of applications across manufacturing, healthcare, and other sectors, facilitating technology implementation, and exerting far‑reaching impacts on diverse industries.

Examples of 3D-printed grippers with and without pneumatic actuation