Theranos Promised to Revolutionize Blood Testing. Scientists May Have Found a Better Way.

Elizabeth Holmes is back in the spotlight thanks to the viral documentary You Can See Everything. Meanwhile, a new study reveals a tiny, flexible sensor that can measure chemicals in the blood in real time. Could this be the kind of breakthrough Theranos promised but never delivered?

Elizabeth Holmes is having another moment.

The former Theranos CEO is the subject of You Can See Everything, a new documentary from filmmakers Nathan Fielder and Lance Oppenheim. The film opened in October 2026 and has become an unexpected box-office sensation, bringing one of Silicon Valley’s most famous scandals back into the public eye.

If you’ve forgotten the story, here’s a quick refresher.

Holmes founded a company called Theranos with an extraordinary promise: Instead of drawing several tubes of blood from your arm, doctors could run a wide range of medical tests using just a few drops from your fingertip.

It sounded wonderful. Blood tests would become faster, cheaper, easier, and less painful. Patients could learn about their health without waiting for traditional laboratory testing.

There was just one enormous problem.

The technology didn’t work as advertised.

Theranos struggled with unreliable results, and its machines could perform far fewer tests than Holmes claimed. The company even used conventional laboratory equipment for much of its testing while presenting investors with a very different picture. Holmes was eventually convicted of fraud.

But here’s what makes the story especially interesting in 2026.

Just as millions of people are revisiting the Theranos scandal, researchers have published a new study in Science Advances describing a device that tackles one of the same basic challenges: How can we measure what’s happening in someone’s blood quickly, accurately, and with less need for repeated blood draws?

Their solution is remarkably different from anything Theranos promised.

Instead of taking a tiny blood sample out of the body, what if we could put a tiny sensor inside a blood vessel and measure changes as they happen?

That’s exactly what scientists are trying to do.

Why blood testing needs an upgrade

Blood tells doctors an incredible amount about our health.

It can reveal signs of infection, organ problems, changes in blood sugar, and dangerous shifts in the chemicals that keep our bodies working.

Two particularly important chemicals are sodium and potassium.

Both are called electrolytes. They help control water movement through the body, support nerves and muscles, and keep the heart beating properly.

Too much or too little potassium, for example, can dangerously change heart rhythm.

This becomes especially important during major surgery.

Imagine a patient undergoing heart surgery. Doctors need to closely monitor the patient’s blood chemistry. But traditional testing often involves drawing blood, sending the sample to an analyzer, and waiting for the results.

According to the new study, that process can take about 8 to 40 minutes in the clinical settings the researchers describe.

That’s a long time when a patient’s condition can change in seconds.

Now imagine replacing those repeated tests with a sensor that continuously shows sodium and potassium levels on a screen.

That’s the goal of this new technology.

Meet the tiny sensor that works inside a blood vessel

In a study published in October 2026, researchers at Hong Kong Polytechnic University developed a device called a multiplexed and implantable fiber sensor, or MIFS.

That’s a complicated name for a surprisingly simple idea.

The device is a thin, soft, flexible fiber containing tiny channels filled with liquid metal.

Its outer surface has special materials that respond to sodium and potassium in the surrounding blood. Those reactions produce electrical signals that can be translated into measurements.

Think of it as a tiny chemical thermometer.

But instead of measuring temperature, it measures the amount of certain chemicals in your bloodstream.

The fiber can bend, stretch, and twist. That’s important because blood vessels aren’t rigid pipes. They move as our hearts beat and our bodies shift.

The researchers designed the sensor to be soft enough to work in that environment without the stiffness of traditional metal electrodes.

And because it can detect two chemicals at once, it offers more information than a sensor that measures just one.

The really clever part is where it goes.

Rather than collecting blood and moving it to a machine, doctors could insert the sensor through a catheter, a thin tube placed into a blood vessel.

The sensor could then provide continuous measurements directly from the bloodstream.

No repeated sample collection is needed while the sensor is monitoring.

That doesn’t mean the procedure is painless or risk-free. Inserting a catheter is much more invasive than a finger prick. But for patients who already need vascular access during surgery or intensive care, the approach could someday offer important benefits.

Did it actually work?

This is where the story becomes especially interesting.

The researchers didn’t just build a sensor and announce that it was revolutionary. They tested it.

First, they placed the device inside rabbits’ blood vessels. They measured sodium and potassium continuously for periods of up to five hours.

At the same time, they collected traditional blood samples and tested them using a commercial medical analyzer.

Then they compared the results.

The sensor’s measurements closely matched those from the conventional equipment.

In one two-hour test involving a rabbit’s jugular vein, the average difference was just 0.164 millimoles per liter for sodium and 0.078 for potassium.

The team also tested fresh blood samples from eight human patients undergoing cardiovascular surgery. Again, the results showed encouraging agreement with standard laboratory testing.

That doesn’t prove the device is ready for hospitals. But it does provide something essential: published measurements that other scientists can examine, question, and attempt to reproduce.

So how does it compare with Theranos?

Both technologies aim to make blood testing faster and more useful. But they approach the problem in very different ways.

There’s another important difference.

Theranos promised to replace much of traditional laboratory testing.

The new researchers aren’t making that claim. Their device measures two specific electrolytes. Although they also demonstrated a sodium-and-glucose sensor in controlled laboratory conditions, that doesn’t mean they’ve built a machine that can test for hundreds of diseases.

The research team is tackling a smaller, more focused problem.

That may be why the work is promising.

But don’t call it the next medical revolution just yet

Before anyone declares that scientists have finally delivered on the Theranos dream, some important limitations remain.

The sensor has not yet been tested as a continuously implanted device in living human patients. Its human blood testing took place outside the body.

Researchers also need to understand what happens when the sensor stays inside a blood vessel for days or weeks.

Will blood cells stick to it? Could it cause clots? Will the materials remain safe? Could its measurements slowly become less accurate?

The researchers acknowledge these challenges.

They’ll also need to demonstrate that the device works reliably across different patients and medical conditions, and that it can be produced and sterilized consistently.

In other words, a promising experiment isn’t the same as an approved medical device.

That’s a distinction worth remembering, especially when discussing Theranos.

The real lesson from Theranos

The Theranos story is often told as a warning about Silicon Valley, charismatic founders, and investors who get carried away by exciting ideas.

But there’s a deeper scientific lesson.

The original dream wasn’t ridiculous.

Making blood tests faster, less painful, and more accessible is a worthwhile goal. Researchers have been working on smaller medical sensors and new diagnostic tools for decades.

The problem with Theranos wasn’t that scientists shouldn’t dream big.

The problem was that the company claimed what its technology could do without the reliable evidence to support it.

A 2016 study published in the Journal of Clinical Investigation compared Theranos blood tests with established laboratory services. Researchers found that Theranos flagged results outside normal ranges about 1.6 times as often as the comparison services, raising questions about the reliability of its testing.

That’s not just a technical problem. Incorrect blood test results can lead to unnecessary worry, missed diagnoses, or inappropriate treatment.

The new fiber sensor offers a different model of scientific progress.

The researchers describe what they built, explain how it works, test it against existing equipment, and identify what still needs improvement.

Their results are encouraging, but they’re also limited.

And that’s how science is supposed to work.

Could this change medicine someday?

Imagine a future hospital where doctors can continuously monitor several key blood chemicals, much like they already monitor heart rate and oxygen levels.

During surgery, they could spot dangerous potassium changes before the next scheduled blood test.

In intensive care, they might see how a patient’s blood chemistry responds to treatment in real time.

Eventually, similar sensors might track glucose, oxygen, medications, or other important substances.

Those applications remain possibilities, not proven outcomes. But the new research suggests that flexible sensors placed directly inside blood vessels could become a useful addition to conventional testing.

And perhaps that’s the most interesting part of this story.

Elizabeth Holmes became famous by promising that a tiny blood sample could reveal almost everything about your health.

Now, as her story returns to movie theaters, scientists are making real progress toward a different future: one in which doctors might not need to draw blood repeatedly to understand what’s happening inside the body.

The new device doesn’t do everything Theranos promised. It doesn’t even try.

But it demonstrates something far more valuable than a grand promise.

It shows what the technology can actually do—and what scientists still need to figure out.

That’s not quite as dramatic as a Silicon Valley scandal.

But it might be a much better way to change medicine.