A single-crystal diamond X-ray pixel detector with embedded graphitic electrodes.

The first experimental results from a new transmissive diagnostic instrument for synchrotron X-ray beamlines are presented. The instrument utilizes a single-crystal chemical-vapour-deposition diamond plate as the detector material, with graphitic wires embedded within the bulk diamond acting as electrodes. The resulting instrument is an all-carbon transmissive X-ray imaging detector. Within the instrument's transmissive aperture there is no surface metallization that could absorb X-rays, and no surface structures that could be damaged by exposure to synchrotron X-ray beams. The graphitic electrodes are fabricated in situ within the bulk diamond using a laser-writing technique. Two separate arrays of parallel graphitic wires are fabricated, running parallel to the diamond surface and perpendicular to each other, at two different depths within the diamond. One array of wires has a modulated bias voltage applied; the perpendicular array is a series of readout electrodes. X-rays passing through the detector generate charge carriers within the bulk diamond through photoionization, and these charge carriers travel to the nearest readout electrode under the influence of the modulated electrical bias. Each of the crossing points between perpendicular wires acts as an individual pixel. The simultaneous read-out of all pixels is achieved using a lock-in technique. The parallel wires within each array are separated by 50 µm, determining the pixel pitch. Readout is obtained at 100 Hz, and the resolution of the X-ray beam position measurement is 600 nm for a 180 µm size beam.

[The determination of surface tension in amniotic fluid as a simple method for the diagnosis of fetal lung maturity (author's transl)]. / Die Messung der Oberflächenspannung im Fruchtwasser als einfache Methode zur Bestimmung der fetalen Lungenreife

For the past several years it is possible to determine the maturity of the fetal lung from the amniotic fluid. Towards the end of the pregnancy the content of surface active substances for instance Lecithine, increases in the amniotic fluid. It is therefore possible to determine the maturity of the fetal lung directly by measurements of the surface tension in the amniotic fluid. In 265 patients from 17 to 42 weeks gestation a total of 340 determinations of the surface tension in the amniotic fluid were carried out. A simple commercial interfacial tensiometer was used. The clinical value of the measurements was determined by the occurrance of a respiratory distress syndrome which was objectively evaluated by the so called Hobel Score. The determination of the surface tension for the amniotic fluid is valuable as a screening test prior to the determination of the relatively expensive L/S ration. The test was compared with the Clements Test which is also a screening procedure.