An inexpensive new medical sensor has the potential to simplify the diagnosis of diseases ranging from life-threatening immune deficiencies to the common cold, according to its inventors at the Stanford University School of Medicine. Their device, called an integrated microfluidics-waveguide sensor, sorts and counts cells in small samples of blood and other body fluids. The developers say the sensor provides an easy way to measure different types of white blood cells, a key component of the immune system. They add that the sensor, which is about the size of an thumbnail, could be deployed in doctors' offices, newborn nurseries, patients' homes, disaster sites and battlefields. "A low-cost way of counting cells could provide point-of-care diagnosis and monitoring for immune disorders, allergies, infections, AIDS, cancer and other disorders," said Manish Butte, who led the team of inventors.