2020-09-24 文章来源：Science Photo Library
Healthy plasma blood test. Electrical field image of a blood sample (plasma) in a healthy patient. This diagnostic procedure relies on colour distribution and pattern of liquid crystals in an electrical field. Plasma from a blood sample is placed on a glass slide coated with voltage- sensitive liquid crystals. An electrical current is applied through the wire at centre. Colours and patterns produced are due to voltage differences, and they indicate here the normal blood plasma pattern. The red ring has a wide circumference with clear outline; the blue (high voltage) area is clear blue with no unhealthy discolouration. In cancer, these areas change shape and colour.