Finally, an underwater messaging app

Don’t you hate it when, after going just five or 10 meters underwater, you lose signal completely? Now this vexing limitation of modern technology is being addressed by researchers at the University of Washington, who have made an underwater communication app that uses sonic signals to pass messages to your other submerged friends. It may sound silly, but millions of people could use this tech in both recreational and professional diving situations.

The communication problem underwater is simple: Rradio waves are absorbed by water, and no signal our phones send or receive can travel more than a few inches without being completely lost. That’s one reason submersibles and the like need a tether: to pass data back and forth to the surface.

Sound waves, on the other hand, travel through water quite readily, and are used by countless aquatic species to communicate. Not humans, though — because the way we make sound only works well in air. So for as long as anyone can remember, divers have communicated to one another using hand signals and other gestures.

Professional divers will have a vocabulary of dozens of signals, from “low on air” to “danger to your right” and anything else you can imagine coming up during a dive. But you have to learn those, and see them when they’re used for them to work; you can bet at least some divers wish they could tap out a message like they do above the waves.

That’s the idea behind AquaApp, a software experiment by the Mobile Intelligence Lab at UW, led by PhD student Tuochao Chen and prolific professor Shyam Gollakota.

The system uses a modified form of “chirping,” or using the phone’s speaker to create high-frequency audio signals to communicate data rather than radio. This has been done before, but not (to my knowledge) in such a simple, self-correcting way that any smartphone can use.

“With AquaApp, we demonstrate underwater messaging using the speaker and microphone widely available on smartphones and watches. Other than downloading an app to their phone, the only thing people will need is a waterproof phone case rated for the depth of their dive,” said Chen in a UW news release.

It’s not as simple as just converting a signal to an acoustic one. The conditions for transmitting and receiving are constantly changing when two people’s locations, relative speeds and surroundings are constantly changing.

“For example, fluctuations in signal strength are aggravated due to reflections from the surface, floor and coastline,” said Chen’s co-lead author and fellow grad student, Justin Chan. “Motion caused by nearby humans, waves and objects can interfere with data transmission. We had to adapt in real time to these and other factors to ensure AquaApp would work under real-world conditions.”

The app is constantly recalibrating itself with a sort of handshake signal that the phones can easily hear and then report back the characteristics of. So if the sender’s tone is received but the volume is low and the high end is attenuated, the receiver sends that information and the sender can modify its transmission signal to use a narrower frequency band, more power and so on.

In their on-site experiments in lakes and “a bay with strong waves” (probably Shilshole), they found that they could reliably exchange data over 100 meters — at very low bitrates, to be sure, but more than enough to include a set of preprogrammed signals corresponding to the old hand gestures. While some (including myself) may lament the loss of an elegant and very human solution to a longstanding problem, the simple truth is this might make dangerous diving work that much safer, or let recreational divers communicate more than “help” and directions.

That said, diving is a pastime and profession steeped in history and tradition, and it’s very unlikely that this digital communication method will supplant gestures — an analog, self-powered alternative is exactly the kind of thing you want ready as a backup if things go sideways.

AquaApp’s code is open source and free to use — take a look and try it yourself at this GitHub repo.

Neurofenix puts on a new spin on home stroke rehabilitation with the NeuroBall

Millions around the world suffer strokes every year, and millions more are in recovery from one they’ve suffered. Regaining the use of affected limbs and capabilities is a long road, but one that can be shortened by intensive rehabilitation efforts — which Neurofenix has shown can take place in the home rather than during frequent trips to the hospital. Its Neuroball device and home therapy platform have led to $7 million in new funding to expand and deepen its platform.

The problem with existing stroke rehabilitation techniques is not that they aren’t effective, but that they’re mostly located in hospitals and thus limit how often they can be engaged with.

“For many, many years rehabilitation, especially neural rehabilitation, has been focused on big bulky equipment in facilities,” explained Gillem Singla, CEO and co-founder (with CTO Dimitrios Athanasiou) of Neurofenix. “We’ve extracted the essence of what needs to be done in neural rehabilitation: It has to be intensive, engaging, motivating and get people to follow up for not just weeks but months and years.”

There are some home rehab devices out there, often in the form of gloves or free motion tracking, both of which work to an extent but haven’t caught on.

“Before even starting to develop the first products, we talked with hundreds of patients, hundreds of therapists, tested everything out — I personally, when a family member had a stroke, had to try many things,” Singla said. “The first urgent need that was being completely neglected was upper limb rehabilitation: 80% of patients suffer from arm and hand impairment after a stroke.”

The company’s solution is the Neuroball, a device that the user can grip and strap into easily and which tracks every movement of the upper limbs from shoulder down to fingertips. It doesn’t do anything radically different from in-hospital setups but rather allows patients to perform the rehabilitative exercises and movements far more frequently, and in a way that reflects their particular needs and capabilities.

The Neuroball at rest beside its tablet interface in a person’s home. Image Credits: Neurofenix

It includes a motion and orientation sensor for wrist, elbow and shoulder movements, and individual sensors for each finger. The ball rests in a cradle but can be picked up and moved freely.

“The key is neuroplasticity,” said Singla. “The evidence shows that the more repetitions a patient does, shows recovery to a greater degree. In a typical session a patient does between 30 and 40 movements with a therapist, and in our clinical trials we showed that patients did more than 600 per day.”

Ease of use, gamification and a bit of algorithmic adjustment are what the company claims result in this huge increase in exercise — and, according to studies they’ve conducted, better outcomes, including improved range of movement and reduced pain.

Image Credits: Neurofenix

It’s easier to put on than a resistive glove, doesn’t take up a lot of space, runs its software on a small, dedicated tablet and has a handful of different games available for each movement the patient needs to perform. These are simple but motivational things, like an endless racer where you squeeze to jump or a Space Invaders game where you rotate your wrist to move your ship. It might not be Fortnite, but it’s better than just seeing a number go up. There are even leaderboards in case a user feels like comparing their progress with a fellow patient.

The promise of improved home rehabilitation is one that will almost certainly appeal to a lot of people for whom going to the hospital or physical therapy office three or four times a week is impractical. Such a schedule would be trying for anyone, let alone a person who might have mobility, speech or upper limb limitations.

Doing the exercises at home and on one’s own time, with the software adjusting to patients’ own rhythms and preferences (such as being more flexible in the morning or evening) leads naturally to far more rehabilitative work being done without extra clinical resources. (“In fact, last week a patient reached 300 days in a row on our platform,” noted Singla.)

The main barrier is affordability: The device is too new to be covered by insurance, though it does qualify for HSA and FSA spending. So far the company, based in Buenos Aires, has conducted a handful of tests showing the Neuroball’s efficacy but not the type needed in order to be covered as a prescribed medical device. But that’s next on the agenda now that they have a new $7 million round in the bank.

“The reason we raised this Series A was we had clear goals in mind,” Singla said, primarily establishing its commercial and clinical presence in the U.S. and then expanding to adjacent forms of therapy.

“Our goal is to be the leader of neural rehabilitation at home, not only for stroke but for trauma,” he continued. “We literally have 400 ideas in our backlog of improvements we can make: expansions, cognitive training, speech and language … if you think about the needs of a neurological patient, they are extremely varied. There’s so many other therapies we can look at.”

The $7 million A round was led by AlbionVC, with participation by HTH, InHealth Ventures and existing investors. The device is not publicly available yet, but curious clinicians and prospective patients are encouraged to get in contact for potential collaboration.

Investors detail their red (and green) flags for startups seeking venture dollars

The past few months have hit the startup community where it hurts — the balance sheet. With inflation rates at record highs, a recession on the horizon and threats of a long winter by venture capital giants like SoftBank, VC money is becoming harder to come by. So where does that leave startups relying on that cash to reach their next levels of operations?

TechCrunch sat down with investors who cover a range of growth stages and industry sectors, with a bent toward mobility and climate tech, to hear how they’re looking at the funding environment today and what their red flags — and green flags — are for startups looking to raise another round.

Most of the investors we spoke to said there is definitely a pullback and general conservatism in funding, with many VCs being a lot more deliberate in their due diligence.

“There is no doubt that investors — especially later-stage investors — are largely sitting on their hands, using this new luxury of taking their sweet time and picking carefully,” Nate Jaret, general partner at Maniv Mobility, told TechCrunch. “The fundamentals of venture investing have not changed, only the pace.”