Petersen, Søren Dahl

Vi præsenterer fleksible silicium sensor platforme, der kombinerer polyimid med polydimethylsiloxan for at tilføje fleksibilitet og biokompatibilitet til silicium sensorerne. Sensor platformene er tiltænkt brug i vævsoximetri ved hjælp af nær infrarød spektroskopi, men kan potentielt også benyttes til andre medicinal sensor. Vævsoximeterne realiseres ved inkorporering af pn-dioder i siliciummet for at danne rækker af infrarøde detektorer. Disse rækker kan derefter anvendes til rumligt opløst spektroskopi målinger, hvor slutbrugeren skal være for tidligt fødte spædbørn.Monte Carlo simuleringer er blevet udført på en model af et spædbarns hoved og de viser kun svage signalændringer som funktion af ændringer i cerebral iltning. En mekanisk og elektrisk analyse af sensor platformene, både ved analytiske udtryk og numerisk simulering, viste at de foreslåede design var gennemførlige.En række forskellige sensorer blev fremstillet, herunder sensorer med detektorer, der er formet som rækker (1D) og som matricer (2D). Mekaniske test af sensor platformene viste, at de kan bøjes til mere end 90°, i deres fulde længder og strækkes med 3 % uden at beskadige de elektriske forbindelsesledninger. Desuden kunne de bøjes mere end 10,000 gange uden angivelse af slitage. IV målinger viste forholdsvis lave mørkestrømtætheder i størrelsesordenen 12-30 nA/cm2 afhængig af detektorernes størrelse og form. Ved at deponere et 30 nm tykt lag af aluminiumoxid, som passivering på detektorerne, kan mørkestrømtætheden reduceres med 30 % for små detektorer. Kvanteeffektiviteter på 80-85 % blev målt for de bedste detektorer. Ved at bruge sort silicium nanostrukturer, kunne reflektansen fra detektorenes overflade reduceres for alle indfaldsvinkler. Dermed vil reduktionen i kvanteeffektivitet blive minimeret, ved et lysindfald på 38° fra normal, til kun 5,2 % i forhold til en reduktion på 9,1 % for sensorer uden sorte silicium nanostrukturer. Som konklusion fungerede både de fleksible sensor platforme og de infrarøde detektorer.We present exible silicon device platforms, which combine polyimide with polydimethylsiloxane in order to add flexibility and biocompatibility to the silicon devices. The device platforms are intended as tissue oximeters, using near infrared spectroscopy, but could potentially also be used for other medical applications. The tissue oximeters are realised by incorporation of pn-diodes into the silicon in order to form arrays of infrared detectors. These arrays can then be used for spatially resolved spectroscopy measurements, with the targeted end user being prematurely born infant children. Monte Carlo simulations have been performed on a model of a neonatal head and they show only weak changing signals as function of changes in cerebral oxygenation. A mechanical and electrical analysis of the device platforms, both by analytical expressions and numerical simulation, indicated that the proposed designs were feasible. A number of different devices were fabricated including devices with detectors formed as arrays (1D) and as matrices (2D). The mechanical testing of the devices showed that they could be bent to more than 90° over their full lengths and strained with 3 % without damage to the electrical interconnects. Furthermore, the devices could be repeatedly bent more than 10,000 times with no indication of fatigue. IV-measurements indicated fairly low reverse bias current densities in the order of 12-30 nA/cm2 depending on the detector size and shape. By depositing a 30 nm thick layer of aluminium oxide, as passivation on the detectors, the reverse bias current could be reduced by 30 % for small devices. Quantum efficiencies of 80- 85 % were measured for the best detectors. By using black silicon nanostructures, the reflectance from the detector surfaces could be reduced for all angles of incidence. Thus, also minimising the drop in quantum efficiency for light incident at 38 from normal to only 5.2 % compared to a drop of 9.1 % for devices without the black silicon nanostructures. In conclusion both the flexible device platforms and infrared detectors were found to work

Online Research Database In Technology

Near Infrared Spectroscopy Systems for Tissue Oximetry

http://orbit.dtu.dk/ws/files/106209449/Soren_Petersen_thesisII.pdf

Near Infrared Spectroscopy Systems for Tissue Oximetry

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Online Research Database In Technology