The introduction of a portable white blood cell counter

At present, most white blood cell counts are done through large-scale equipment in the central laboratory. In a hospital, if a doctor collects blood samples of patients, it usually takes several days to get detailed results. Recently from the California Institute of Technology, researchers at LeukoDx have developed a portable device that can achieve results in a few minutes with a fingertip.

The leader of this research was the famous Chinese scientist Dr. Dai Daichang. Professor Dai used the volumetric circuit process technology in 1989 to invent the world’s first micron-sized electrostatic motor, and thus became one of the pioneers in the field of MEMS. . He has published many landmark works on the research of micro-electromechanical components and systems, microfluidics, biochips and human neuroimplantation devices. He has also cultivated countless famous university professors and leaders.

For this latest result, he said, "Our new system is very suitable for use in hospitals or central clinical equipment." "This is the first time that real-time testing has been achieved."

Portable leukocyte counters can be used to improve outpatient monitoring of patients with chronic diseases such as leukemia or other cancers. And it can also be used in combination to help telemedicine in remote areas. It can even be used by astronauts. The astronauts are exposed to radiation for a long time and use this equipment to perform tests when they are still in space. The results of this research will be published in the April 16 issue of Lab on a Chip.

There are five types of white blood cells, each with its own distinct function, which means that counting separately will be of great help. In general, lymphocytes use antibodies to attack certain viruses and bacteria; neutrophils are particularly good at fighting bacteria; eosinophils can target parasites and certain infectious agents; monocytes respond to inflammation, It also recruits leukocytes in body tissues, and the rarest one: basophils are used to attack certain parasites.

"If we can put a fast leukocyte counter in the doctor's office," Wendian Shi, the first author of the article, said, "So when you deal with viral infections or bacterial infections, you can immediately With the result, the doctor can prescribe the right medicine."

This device can complete the counting of all five cells in a leukocyte sample, accurately distinguishing four major subtypes: lymphocytes, monocytes, eosinophils, and neutrophils. In addition, the fifth cell in the clinical test can be detected: abnormal expression of basophils, these cells are very rare (only less than 1% of all leukocytes).

The entire new system is 12" x 9" x 5" in size, making it easy to create a hand-held device, so it can be applied in many ways.

In this paper, the researchers also designed a detection method that stains white blood cells with three dyes that excite bright fluorescence by laser light. The blood sample is first treated with fuel. The first fuel binds to the DNA in the leukemia cell nucleus, so that it is easy to distinguish leukocytes from red blood cells, and the other two fuels can distinguish different leukocytes.

The key part of this portable device is a 50 μm long silicone transparent channel with a cross section of only 32 μm to ensure that only one white blood cell can pass through this channel detection area at a time.

When the dyed blood sample passes through this microfluidic channel and reaches the detection area, the laser will cause them to generate fluorescence. The reflected light is then split into two beams by a mirror. The subdivisions represent green and red fluorescence.

Using this staining method, researchers can analyze the characteristic quantities of red and green light emitted by different white blood cells. Therefore, it is highly accurate to determine the number of white blood cells.

Shi Wendian stated that his ultimate goal is to develop a portable device to help patients with chronic diseases. “These patients hope to find a balance between treatment and normal life, and our device will help them monitor their physical changes at home.”