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FORCE SENSORS MOVE BEYOND TOUCH SCREENS


James Hayward at IDTechEx Research, studying the use of force sensors in user interfaces, predicts themarketwill reach $1.8bn annually by 2027. Since themobile era, touch


screens have been the core user interfacewith electronic devices. But as the technology behind touch interfaces begins to saturate,many nowlook beyond touch for the future of user interfaces.While advanced solutions including voice and gesture detection right through to perceptive computing are suggested,many are looking for the bestways to improve the existing platform. Force sensing can add an additional dimension to touch interfaces, a trend strongly visible frommarket leaders during 2015 and 2016. While force sensors aren’t


new– their use dates backmore than 40 yearswhen theywere first used inmusical instrument toys –withmany high profile consumer electronics products nowcontaining them(most notably Apple’s smartwatch, laptop and smartphone products), this has quickly dominated themarket. As such, user interface is undergoing significant change,with force sensing as a prominent early step.


NOVEL LIGHT SOURCES MADE OF 2D MATERIALS


Two-photon sources are particularlywell suited for tap- proof data encryption. Physicists fromthe University of Würzburg have designed a light source that emits photon pairs. The experiment’s key ingredients: a semiconductor crystal and some sticky tape. So-calledmonolayers – solid


materials ofminimumthickness – are at the heart of the research. These “super materials” showgreat promise


to revolutionisemany areas of physics. In two-dimensional form, they frequently exhibit unexpected properties that make theminteresting for research. The so-called transitionmetal dichalcogenides (TMDC) are particularly promising. They behave like semiconductors and can be used tomanufacture ultra-small and energy-efficient chips, for example.Moreover, TMDCs are capable of generating light


when suppliedwith energy. Dr Christian Schneider,


Professor Sven Höfling and their research teamfromthe Chair of Technical Physics of the Julius- Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, have harnessed exactly this effect for their experiments. First, amonolayerwas


produced using a simple method. This usually involves a piece of sticky tape to peel a multi-layer filmfroma TMDC crystal in a first step. Using the same procedure, thinner and thinner layers can be stripped fromthis film. This process is repeated until thematerial on the tape is only one layer thick. The researchers then cooled


 Artistic representation of a two-photon source showing the monolayer emitting exactly two photons of different frequencies under suitable conditions, here shown in red and green


thismonolayer down to a temperature of just above absolute zero and excited itwith a laser. This causes the monolayer to emit single photons under specific conditions. “Wewere nowable to showthat a specific type of excitement produces not one but exactly two photons,” Schneider explained. “The light particles are generated in pairs so to speak.”


HIGH SENSITIVITY LIGHT DETECTOR TO BOOST IMAGING?


A research teamled by Professor Hele Savin at Aalto University has developed a new light detector that can capture more than 96 per cent of the photons covering visible, ultraviolet and infrared wavelengths. The newconcept for light


detection kindled fromthe team’s earlier research on nanostructured solar cells and the nanostructure used in the light detector is similar to that used by the teama couple of years ago in their record high- efficiency black silicon solar cells. “Present-day light detectors


suffer fromsevere reflection losses as currently used anti- reflection coatings are limited to specific wavelengths and a fixed angle of incidence. Our detector captures light without such limitations by taking advantage of a


 Light is captured using a nanostructured surface that overcomes the limitations of anti-reflection coatings


nanostructured surface. Low incident angle is useful especially in scintillating x-ray sensors”, Savin explained. “We also addressed electrical


losses present in traditional sensors that utilise semiconductor pn-junctions for light collection. Our detector does not need any dopants to collect light – insteadwe use an inversion layer generated by atomic layer deposited thin film.” The teamhas filed a patent


application for the newlight detector. The prototype detectors are currently being tested in imaging applications related tomedicine and safety.


December 2016 /// Environmental Engineering /// 5


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