If you're one of the 8 million Americans who donate blood each year, you know that before you can give from the arm, you're going to get stuck in the earlobe or fingertip. This predonation anemia test boosts the nurse's risk of blood exposure and adds to the bill for biohazardous-waste disposal. Philadelphia-based Cytometrics plans to put an end to those problems with the Hemoscan, a device that tests blood-without drawing any.

Slip a thermometer-like probe under your tongue for a moment, and the Hemoscan tells instantly whether you're good to give. The probe houses a light source and a miniature camera that captures a video image of blood flowing through tiny vessels; a computer analyzes the spectrum of the reflected light and calculates the levels of red cells and hemoglobin. Cytometrics, working in partnership with the American Red Cross, hopes to have the device on the market next year.