Deuterated silicon nitride turns one wavelength into a 1.7-octave spectrum
Dawn Tan and Luo Xianshu obtained light from 587 to 1883 nanometres in a nitride waveguide built from deuterated silane. A pillared chip at Institute of Science Tokyo changes which cells it sorts between 23 and 26 degrees Celsius.
Science··Midday
Deuterium moves the absorption peak to 2.1 microns
Dawn Tan of the Singapore University of Technology and Design and Luo Xianshu of the A*STAR Institute of Microelectronics built silicon nitride waveguides from deuterated silane. Replacing hydrogen with deuterium moves the bond's absorption peak away from telecom wavelengths to around 2.1 microns, so the film no longer needs annealing at up to 1200 degrees Celsius. The 800 nanometre-thick film is deposited below 400 degrees Celsius on 200 millimetre wafers, a standard semiconductor format, and loses 0.54 decibels per centimetre.[1]
One pump fills 587 to 1883 nanometres
Pumped at 1555 nanometres, a 5.21 centimetre device gave light from 587 to 1883 nanometres, with spectral coherence above 0.81 at moderate pulse energies; at the highest energies the spectrum widened while coherence fell. One infrared wavelength is thus turned into a 1.7-octave spectrum. The paper is in Optics Express.[1]
A two degree rise changes which cells the chip sorts
A team at Institute of Science Tokyo lined a microfluidic channel with pillars made of a temperature-responsive polymer. The pillars swell and narrow the gaps when cool, then shrink and widen them when warm, so a temperature gradient set by two Peltier elements gives one chip several separation thresholds. In tests between 23 and 26 degrees Celsius the device recovered 13.0 micrometre particles at 92.9 per cent purity, 9.94 micrometre particles at 90.0 per cent and 5.65 micrometre particles at 97.8 per cent. Separating MCF-7 breast cancer cells from diluted whole blood left 94.8 per cent of them viable. The advantage is that one chip handles several separation tasks without a redesign of its geometry. The study is in Lab on a Chip.[2]
