Soft Pneumatic Gripper

Rigid robot grippers are strong but clumsy with delicate things — fruit, eggs, soft packaged goods — where a hard jaw either crushes the object or drops it. Soft robotics answers with compliant fingers that conform to the object's shape, distributing the grip force. This project builds the canonical student version: two silicone bellows fingers, cast or assembled with chambered walls, mounted on a 3D-printed palm and base. A miniature 12 V air pump inflates them through silicone tubing; as internal pressure rises the fingers curl inward and wrap the object. A pressure gauge on the line and a control valve let the student map pressure against curl angle and grip success on a set of test objects. The build covers soft-actuator fabrication, pneumatic plumbing at low pressure, and the design logic of compliance — with honest limits on what a student-scale soft gripper can lift.

1. The silicone fingers are fabricated with internal air chambers and mounted on the 3D-printed palm.
2. Silicone tubing connects each finger to the miniature air pump through the control valve and pressure gauge.
3. With the valve open, the pump inflates the chambers; the asymmetric chamber walls force each finger to curl inward.
4. The student places a test object between the fingers and raises pressure until the fingers wrap and lift it.
5. The gauge reading at successful grip is recorded per object, building the pressure–grip table for the report.
6. Releasing the valve vents the fingers, which relax open and release the object.

Tech stack:

• Silicone bellows actuators
• 3D-printed PLA frame (CAD)
• 12 V miniature diaphragm air pump
• Analog pressure gauge
• Manual control valve
• Silicone pneumatic tubing
• 12 V DC supply

• [Silicone bellows fingers] Two chambered soft fingers curl when pressurized, conforming to the object's shape instead of pinching it — the defining soft-robotics behavior.
• [3D-printed palm and base] The mounting frame is 3D-printed, so the student owns the full CAD-to-part workflow and can iterate the geometry.
• [Miniature air pump] A small 12 V diaphragm pump supplies the actuation pressure — no compressor or lab air line needed for the demonstration.
• [Pressure gauge] An analog gauge on the air line shows actuation pressure live, so the pressure–curl relationship is measured, not guessed.
• [Control valve] A manual valve meters inflation and release, letting the student demonstrate graded gripping from a light touch to a full curl.
• [Test-object grip study] A documented procedure grips a set of everyday objects (wooden block, ball, soft pouch) and records success vs pressure — the experiment at the heart of the report.
• [Modular finger mounting] Fingers detach from the palm, so the student can test one finger's curl profile independently before assembling the gripper.

• Working soft pneumatic gripper prototype
• 3D CAD files for palm, base and finger moulds
• Finger fabrication procedure (moulding/assembly guide)
• Pneumatic plumbing diagram
• Grip-test procedure with object set and recording sheets
• Project report PDF (soft robotics, compliant mechanisms, test results)
• PPT presentation for final review
• Viva Q&A preparation document

• Grip force and payload are design targets, not measured claims — the student measures what their build achieves in the grip study.
• Light objects only; this student-scale gripper cannot lift industrial payloads and does not claim to.
• Silicone fingers wear and can puncture — the manual covers inspection and repair, and spare-finger fabrication is documented.
• Cycle speed is limited by the small pump's flow rate; fast pick-and-place is out of scope.
• Open-loop control only — no force or position feedback on the fingers as shipped.