A team at Purdue University have designed a mobile microgripper (MMG) that can handle fragile cell spheroids with controlled force and high spatial precision.

Spheroids have become integral to tissue engineering, as they can replicate biological interactions between cells and the surrounding matrix- but they are exceedingly fragile, meaning handling can be problematic.

“Other techniques for cell spheroid bioassembly can affect the tissue construct and/or apply limited manipulation forces,” said Dr David Cappelleri, professor of mechanical engineering and biomedical engineering at Purdue.

“The force-sensing MMG … addresses these current issues by allowing the safe bioassembly of different spheroids into a single construct,” he said.

But in a new study, a team at Purdue University, West Lafayette, Indiana, have created a tiny robotic gripper, that can manipulate spheroids without causing tissue damage.

The robot uses a magnetic microscopic claw mechanism

The wireless mobile microrobot gripper consists of two articulated arms connected by a hinge, allowing controlled closure to grasp the spheroid cells with minimal force, operating under magnetic actuation. External magnetic fields enabled both movement of the device and precise control of the gripping jaws. This design maintains combability with biological environments whilst subverting the need for direct mechanical contact and bulky instrumentation.

“This was a big part of the design – to figure out a way to use magnetic fields for both locomotion and for control of the opening and closing of the gripper jaws,” added Cappelleri.

The force-sensitivity of the MMG continuously monitors the spheroids and adjusts its grip accordingly, meaning operators can handle a variety of spheroid shapes and structures, reducing the risk of damaging the cell during handling.

Computational modelling and in vitro experiments have confirmed the MMG can handle cells safely

The research team evaluated the microgripper’s performance and established that the magnitude of force applied during spheroid manipulation was within viability limits after transfer. Future study will work on extending the microgripper’s ability to work on three-dimensional tissue fabrication, with a long-term objective to construct fully functional engineered tissues.

So far, the MMG has successfully eneabled assembly of spheroids into planar cellular sheets, which will serve as a foundational structure for future constructs. These more elaborate constructs are similar to structures that house the heterogenous cell populations in in vivo tissues.

The team also plan to transition from manual operations to automated control of the microscopic robots, which could increase production across quantity and efficacy.

In the supplementary video below, you can see representative experimental validation tests, specifically of MMG spheroid placement and PDMS sphere micromanipulation.