When scaling down is as vital as scaling up

Robotics continue to scale down – but can researchers include the autonomy necessary for the medical intervention that will prolong life?

Tiny robots could be a big deal for Longevity. Microbots (small) and nanobots (even smaller) can mean diagnosis and repair can be effected non-invasively and obstacles like the immune system and blood-brain barrier can be overcome.

Longevity.Technology: Stop! HAMR time. Well, Harvard Ambulatory MicroRobot time … We often look at companies and tech that are scaling up, but the other end of the spectrum is important when it comes to medical robotics.

Working at a nanoscale means the physics is different; surface area becomes more critical than volume and this means forces of attraction and contact – such as adhesion – have more influence on movement than gravity does. In fact, at this scale, where mass is miniscule, the effect of gravity is almost negligible and research can benefit from a counter-intuitive approach to material design.

Applying scaling down lessons to Longevity could result in bots that can clear brain plaque deposits and delay Alzheimer’s, repair joints and prevent arthritis and maybe even tackle senescence at a cellular level.

But how small is too small? As the bots shrink, researchers have to avoid jettisoning functionality and autonomy in favour of a smaller size. Ensuring power systems have a high power density, or mimicking nature with hydrogels that can propel themselves by changing shape, or with flagellum-like tails, are two of the ways these bots can be small, but mighty, and can navigate to exactly where they are needed.

Retaining autonomy is key for ensuring these bots are maximised for Longevity success. Autonomous bots can navigate from one point to another, using an untethered power source and are able to identify and traverse different terrains. This is where scaling down can prove vital.

A team at Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering has constructed HAMR-JR, a half-scale version of the cockroach-inspired Harvard Ambulatory Microrobot or HAMR. HAMR-JR is fast, strong and can do pretty much everything its predecessor can.

HAMR-Jr is only slightly bigger in length and width than a penny, making it one of the smallest yet highly capable, high-speed insect-scale robots. (Image courtesy of Kaushik Jayaram/Harvard SEAS)

“Most robots at this scale are pretty simple and only demonstrate basic mobility. We have shown that you don’t have to compromise dexterity or control for size,” said Kaushik Jayaram, a former postdoctoral fellow at SEAS and Wyss and first author on the paper.

“The wonderful part about this exercise is that we did not have to change anything about the previous design. We proved that this process can be applied to basically any device at a variety of sizes [1].”

The research team used PC-MEMS (printed circuit microelectromechanical systems), a fabrication process in which the microbot’s components are etched into a 2D sheet and then popped out in its 3D structure. In order to build HAMR-JR, the team shrunk the 2D sheet design of the robot, along with the actuators and onboard circuitry, to recreate a robot which was smaller, but which had all the same functionalities.

The team also developed a model that can predict movement metrics like running speeds, foot forces and payload based on a target size; this model can be used to design different systems with specific requirements [2].

Co-author Robert Wood, Charles River Professor of Engineering and Applied Sciences in SEAS and Core Faculty Member of the Wyss, said: “This new robot demonstrates that we have a good grasp on the theoretical and practical aspects of scaling down complex robots using our folding-based assembly approach [3].”

As autonomous surgeon bots become more prevalent, there would be additional bonuses. Communicating via the Internet of Things, the bots could share insights from their experiences and mistakes in numerous procedures and anatomical knowledge from thousands of patients, creating a vast knowledgeable network, that could help change the future of our lifespan and healthspan.

[1] https://bit.ly/3ije7O7
[2] https://arxiv.org/abs/2003.03337
[3] https://www.sciencedaily.com/releases/2020/06/200603122948.htm