Social robots see smell

by Angela Herring

“The thing that’s been missing in robotics is a sense of smell,” said biology pro­fessor Joseph Ayers.

For more than four decades, he has been working to develop robots that do not rely on algo­rithms or external con­trollers. Instead, they incor­po­rate elec­tronic ner­vous sys­tems that take in sen­sory inputs from the envi­ron­ment and spit out autonomous behav­iors. For example, his team’s robo-​​lobsters are designed to seek out under­water mines without fol­lowing a pre­de­ter­mined course.

“Now people want robots to do group behavior,” said Ayers, noting that social insect colonies are the per­fect model. “If you’re doing large field explo­rations for mines, you want to have 20 or 30 robots out there.” In order to get robots to coop­erate with each other, he needs them to act like ants or bees or termites.

Bees waggle their behinds to com­mu­ni­cate. Ants use almost two dozen scent glands, depositing a trail of “stinks” as they go about their busi­ness. It’s this behavior that Ayers wants to mimic in his next gen­er­a­tion of bio­mimetic robots.

To do so, he needs elec­tronic devices that can sense chem­ical inputs, such as explo­sives. His idea is to inte­grate var­ious micro­elec­tronic sen­sors that can inter­face with living cells. For example, a bac­te­rial cell pro­grammed to bind odor­ants in the envi­ron­ment may elicit a con­for­ma­tional change; that change may trans­late to an influx of cal­cium ions, which are detected by a second cell that is pro­grammed to gen­erate light when bound to cal­cium. In this way, Ayers said, “you can see smell.”

That output would then trigger micro­elec­tronic actu­a­tors that tell the robot to per­form a par­tic­ular action, such as moving toward or away from the stimulus.

But in order for any of this to play out, some­body needs to build these futur­istic devices.

Enter bio­engi­neering grad­uate stu­dent Ryan Myers, who built one of the world’s only e-​​jet printers for Ayers’ lab. He learned the nearly arti­sanal craft from Andrew Alleyne, a pro­fessor of engi­neering at the Uni­ver­sity of Illi­nois who per­fected the tech­nology. Myers’ work earned him the inter­dis­ci­pli­nary research award at the Research, Inno­va­tion, Schol­ar­ship, and Entre­pre­neur­ship expo ear­lier this year.

According to Ayers, “inkjet printing is the industry stan­dard for organic elec­tronics.” This state-​​of-​​the-​​art tech­nology is already paving the way for a new industry of inex­pen­sive, ver­sa­tile elec­tronics, such as the curved tele­vi­sion that debuted ear­lier this month.

The problem, at least for Ayers’ lab, is that inkjet printers can only deposit droplets 30 microns or larger. While that might seem suf­fi­ciently teeny to the rest of us, it’s not small enough for Ayers, who needs elec­tronics fea­tures that are smaller than a living cell.

That’s where the “e,” for elec­tro­hy­dro­dy­namic, comes into the pic­ture. In the case of “tra­di­tional” inkjets, a droplet is deposited onto a sur­face through back­pres­sure alone. This means that some of the ink spreads out when it lands. E-​​jet printers incor­po­rate a voltage poten­tial between the printer head and the sur­face, as well as a small vacuum force on the other side. When the ink drops from the printer head, it is both pushed and pulled to the exact spot for which it’s intended. The tech­nology allows them to print droplets as small as 250 nanometers.

At a frac­tion of the diam­eter of a living cell, “we can print many fea­tures per cell instead of many cells per fea­ture,” said Ayers. That is, they can now pro­duce micro­elec­tronics with high enough res­o­lu­tion to inte­grate with bio­log­ical systems.

The research team is now hard at work printing bio­com­pat­ible pho­to­di­odes, nitric oxide sen­sors, and pho­to­sen­sors to inte­grate into their robo-​​lobster and rob-​​lamprey projects. It’s just the next step in Ayers’ goal to create a “social-​​robot.”

Originally published in [email protected] on August 12, 2013

College of Science