Whether it’s adhesions that mimic gecko toes or robotic technology inspired by land animals like cheetahs, many developments in science are inspired by nature. A team of mechanical engineers at Rice University in the United States took inspiration one step further, creating a new field of study called necrobiotics turning a dead wolf spider into a robot.

Spiders use their legs to walk and jump, but unlike most animals, they do so with the force of pressure rather than muscle contraction and extension. Spiders don’t have the ability to extend muscles in their legs, so after flexing, they push blood into their legs like a hydraulic system, allowing for powerful movements like jumping. When the spider dies, the legs curl up because there is no pressure present.

The team reintroduced pressure into the spider’s legs via a needle in its back, adding pressure to extend the legs and removing pressure to flex them. This allowed the researchers to use the legs as an actuator gripper to pick up items. They demonstrated the spider’s ability to pick up oddly shaped and delicate items and lift objects up to 130 percent above its body mass.

Its ability to pick things up isn’t the only benefit of using bio material: Nature will take care of the waste.

The actuator can camouflage in natural surroundings and the material would eventually fully biodegrade — unlike bioinspired or biohybrid mechanisms that use synthetic materials. The actuators were used in 700 actuation cycles before decaying — only one of the limitations of working with dead organisms.

Seven hundred actuation cycles is a low number compared with non-bio actuator grippers. A synthetic gripper used in farming to pick up lightweight food like mushrooms or berries, for example, would complete between 263,000 and 700,000 cycles.

In addition to limited performance, there are variables to consider when working with bio material.
Not all wolf spiders are exactly the same size so will not have the same longevity. Additionally, variation in size could affect the strength of the gripper.

“The concept of necrobiotics could play a role in inspiring more sustainable fabrication of actuators to reduce the accumulation of technological waste,” the team says in Advanced Science. Though this is a new area of research, they will continue to explore other organisms with similar hydraulic- movement systems.