2023-2026

Metamaterial soft grippers

We use metamaterials to balance soft touch with sufficient stiffness in the mechanical response of soft grippers for harvesting delicate fruits. The metamaterial grippers obtained have advanced shape morphing and a larger contact area with more uniform pressure distribution to preserve the fruit's integrity.

Soft grippers are appealing alternatives to rigid counterparts due to their capability to passively adapt to complex shapes and to interact safely with the environment and delicate objects. Mechanical metamaterials used as the gripper's infill can further improve these functionalities. This projects aims to design soft grippers with integrated metamaterials to advance their shape morphing performance.

Curious to know more? See our findings below.

How to assess the performance of soft grippers?

The mechanical behavior of soft grippers is often estimated in qualitative demonstrations, design-specific tests or isolated metrics, complicating the comparison between different designs and hindering design optimization. We have proposed a quantitative and experimentally validated performance assessment framework for soft grippers that provides a universal basis for benchmarking and architecture-driven optimization of soft robotic grippers. More details in: I. Spanos, A.J.P. Kottapalli, A.O. Krushynska "Redefining Grip: Quantitative Evaluation of Soft Grippers", Materials & Design, 269, paper 116759 (2026) (link).

How to improve shape-morphing performance of soft grippers?

We propose to use so-called chiral metamaterials that have intrinsically coupled translational and rotational motions and thus enable to better control the pressure distribution and contact area at the gripper-object interface. More details can be found in: Spanos, I., Veenhuizen, J., Krushynska, A. O. (2026). Enhanced shape morphing of soft grippers enabled by chiral metamaterials, under review (link).

Can we control the force applied by soft grippers?

Definitely! For this, we have used flexible piezocapacitive sensors on the surface of a grasped object to measure the applied pressure on objects of different shape and dimensions. More details in the Ph.D. thesis of D.A. Guzman Embus "Sensory system for texture and pressure detection in soft grippers applications" (2026).

Can we have an autonomous robot that detects and harvests tomatoes using soft grippers?

High-school students Tom de Groot, Luuk Schouten, and Tim Wezeman from H.N. Werkman City Lyceum have shown that it is possible. See on the left the video of their robot using an intergtaed camera and a time-of-flight sensor to identify and safely pick-up a tomato.