Hand-Cranked Chip Reads Blood Type and Red Cell Level From One Drop in a Minute
A National Taiwan University team's plastic microfluidic device needs no electricity and about 3 microliters of blood, and matched hospital analyzers in tests on 21 patient samples.
When someone is badly injured, doctors urgently need two facts: the patient's blood type, so a transfusion is safe, and the hematocrit, the share of the blood made up of red blood cells, which reveals blood loss or anemia. Hospitals measure both with large machines that need electricity and trained staff, which are often unavailable in ambulances, disaster zones and remote clinics.
A team led by professor Chien-Fu Chen at National Taiwan University has built a simpler alternative: a small plastic chip spun by a hand-cranked centrifuge that needs no electricity. It takes about 3 microliters of blood from a finger prick and returns both measurements in about one minute. The study is published in Biosensors and Bioelectronics.
Turning the crank pushes the blood through winding channels preloaded with reagents for the A, B and Rh blood groups. If the blood matches a reagent, its red blood cells clump together. A gap about one-tenth the width of a human hair at the end of each channel traps the clumps while letting single cells pass, so a red band forms in the channel. Red bands in the A, B and Rh channels reveal the blood type at a glance.
The band's length does double duty. More red blood cells make a longer band, so reading its length against a printed scale on the chip gives the hematocrit.
The researchers tested the device on 21 hospital patient samples. Its results closely matched those of standard hospital analyzers, and readings stayed consistent regardless of how fast the crank was turned, an important point for a tool meant to be used by people with little training under stress. "No electricity or special training needed," said Chen, a distinguished professor at the Institute of Applied Mechanics at National Taiwan University.
The sample size is small, and the work is a laboratory demonstration rather than an approved clinical product. Devices used for transfusion decisions would need much larger trials and regulatory review before anyone relied on them in an emergency.
Even so, the design addresses a real gap. Blood typing and hematocrit checks are among the first tests needed after major blood loss, yet they usually require a hospital laboratory. A chip that fits in a first-aid kit and works in a minute with a hand crank could in principle bring those tests to places where there is no power, no analyzer and no technician. The paper is Chien et al., "Hand-powered micro-slit–gated microfluidics for concurrent blood typing and hematocrit estimation," Biosensors and Bioelectronics (DOI 10.1016/j.bios.2026.119215).
