blood test

A stain is found at a crime scene. The expert takes a swab, and a few hours later the instrument outputs a list of proteins that made up the fluid. Previously, a rapid test could be wrong if multiple fluids were present: blood mixed with saliva, and the strip gave a false result.

Every heartbeat sends a wave through the cerebral arteries that not only pushes blood but also briefly inflates the vessel. The arterial wall, like a tightly stretched rubber tube, passes that motion to the neighboring brain tissue, and the brain pulses ever so slightly in time with the heartbeat.

A drop of blood from a fingertip lands on the white membrane of a cartridge. Twenty minutes later, the phone shows whether Lyme disease is present or not. No test tube, no centrifuge, no waiting for days. Usually, for such a test, blood is first spun in a centrifuge to separate the liquid part — the plasma.

A glucose meter that doesn't prick your finger but just looks at your wrist: that's the dream for millions of people with diabetes. It's the promise of algorithms that extract glucose levels from the ordinary pulse signal, the photoplethysmogram (the same one that measures heart rate in smartwatches).

Diabetes is a constant reminder of needles. To check glycated hemoglobin (HbA1c — a blood protein that reflects average sugar over three months), you need regular blood draws from a vein. It's unpleasant, requires a lab, and takes time. And if you live far from a city, every test becomes a major expedition. The new iGLU 5.0 device changes the game.

Your finger is a living sensor: beneath the skin, arteries pulse in time with your heart. Traditional blood pressure cuffs squeeze your arm and give a single number, but this ring uses eight electrodes to pass a weak current through the tissue and map blood flow.

A drop of blood from a fingertip is like a photograph. One is just a snapshot, but collect them over years and you get a movie of your health.

In a hospital, blood from a finger prick usually goes to the lab, and the result comes back the next day. The new method promises to cut that wait to a few minutes. Instead of catching light reflected off a sample, it reads the electrical voltage that arises at the boundary between two media, like the faint tingle you feel when you touch a battery with wet fingers.

In a heart-lung machine, blood flows through narrow tubing and past rapidly spinning pump blades. Sometimes red blood cells can't take it: their membranes rupture, and hemoglobin spills into the plasma. For a patient, this is like pouring sand into a car's fuel system — small damages accumulate and wreck the whole mechanism.

A drop of blood is a bustling city in miniature. Thousands of different molecules scurry through it, each leaving its own trace. But peering directly into this city is hard: the streets are tangled, and there are so many inhabitants that counting them all individually is out of the question. Scientists have found a way to listen to the whole city at once, without singling out its residents.