Li et al. 2017;3:e1602045

Inspired by a manta ray, scientists have built a small, squishy robotic fish that can swim and turn by remote control. Using the surrounding water as an electrode to capture and distribute electrical energy, the self-powered machine treads water twice as fast as similar robots and can function in a range of water temperatures. The biggest advance, though, is its energy efficiency — the robot can operate for three hours without recharging.

"[It] is an elegant demonstration of the emerging capabilities of soft robots," says Harvard's Michael Wehner, who last year built an octopus robot powered by hydrogen peroxide.

Why it matters: Robots will soon move out of warehouses and hospitals and into harsher, less predictable environments where they'll have to navigate small spaces and interact with humans (they may eventually even move through our bodies to diagnose disease in a next generation of endoscopies). To make it, they'll need to be compact, soft and flexible.

Go deeper

Updated 2 hours ago - Politics & Policy

Coronavirus dashboard

Illustration: Aïda Amer/Axios

  1. Politics: Chris Christie: Wear a mask "or you may regret it — as I did" — Senate Democrats block vote on McConnell's targeted relief bill.
  2. Business: New state unemployment filings fall.
  3. Economy: Why the stimulus delay isn't a crisis (yet).
  4. Health: FDA approves Gilead's remdesivir as a coronavirus treatment How the pandemic might endMany U.S. deaths were avoidable.
  5. Education: Boston and Chicago send students back home for online learning.
  6. World: Spain and France exceed 1 million cases.

Early voting eclipses 2016 total with 12 days until election

People stand in line to vote early in Fairfax, Virginia in September. Photo: Tasos Katopodis/Getty Images

Americans have cast more than 47.1 million ballots in the 2020 presidential election, surpassing the total early-vote count for 2016 with 12 days left until Election Day, according to a Washington Post analysis of voting data.

Why it matters: The election is already underway, as many states have expanded early and mail-in voting options because of the coronavirus pandemic.

What to expect from the final debate of the 2020 election

Trump and Biden at the first debate. Morry Gash-Pool/Getty Image

Watch for President Trump to address Joe Biden as “the big guy” or “the chairman” at tonight's debate as a way of dramatizing the Hunter Biden emails. Hunter's former business partner Tony Bobulinski is expected to be a Trump debate guest.

The big picture: Trump's advisers universally view the first debate as a catastrophe — evidenced by a sharp plunge in Trump’s public and (more convincingly for them) private polling immediately following the debate.

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