Engineering of Tecans LS series Format flexibility

The Tecan LS series microarray scanner provides flexible scanning technology to automatically scan many different format samples such as: glass slides; evanescence resonance glass slides (NovaChip, Novartis Pharma, Basel); plastic slides (black or transparent); segmented slides and plates with tiny upper structure (e.g. HTA Greiner-Bioone); clear-bottom microplates (e.g. Nunc, Greiner-Bioone, Matrix Technologies, Schott-Nexterion Telechem); small micro-fluidic chips; membranes (FAST slides from S&S/Whatman); mini PAA gels, hydrogel protein arrays (PerkinElmer); CodeLink hydrogel slides (Amersham/GEHC); mirrored or gold-coated slides; tissue arrays; colony plates; and coverslips. Basically all formats in the range of 6 x 6-mm square to 127 x 85-mm square and up to 15 mm in height can be placed on the sample tray of the LS and automatically focused. The fluorescing sample itself can be 5 mm deeper than the top of the chip or chip-adapter. LS enables the scanning of more complex formats than just a glass slide of 3 x 1 inch size and 1 mm thickness.

Selective excitation with lasers

Laser for selective excitation

The LS series of scanners provide selective excitation by the option to choose from four different lasers. A mix or contamination of different wavelengths coming from one laser is prohibited by band-selective filters for all lasers. They excite at their predetermined fixed wavelengths only (633 nm red, 532 nm green, 594 nm orange/yellow and 488 nm blue). Currently two lasers are industry standard gas lasers: HeNe for selective 633 and 594 nm excitation. All four lasers can be placed in the same housing including the solid-state 488- and 532-nm laser. Laser power for three out of the four lasers is optimized for microarray fluorescence scanning (10 mW 532 nm, 7 mW 633 nm, 3 mW 594 nm) and is running with 100% capacity, except for the 488-nm laser, which is continuously adjustable to avoid massive bleaching (1-20 mW). Note that gas lasers by their very nature slowly lose 30% intensity over time, which results in a 20% loss of sensitivity. Usually HeNe gas lasers are not 'leaky' below this level. HeNe lasers in LS Reloaded are rated for 20 000-40 000 working hours. Both solid-state lasers of the LS Reloaded are specified for more than 8 000 working hours. After the specified lifetime is reached, 80% of the lasers are still working. After 20 minutes warm-up time the HeNe lasers are very stable during measurement and therefore no active referencing is necessary compared to several solid-state lasers. In order to avoid noise it is recommended to reduce referencing activ ity (e.g. of laser) during a measurement. Calculation of noise coming from instable lasers increases noise in the image. The variation of stable gas lasers in the LS series is about 0.5%. The 488-nm solid-state laser is internally power-stabilized.

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