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Combining bottom-up with top-down method, devices based on horizontally aligned and network single-walled carbon nanotubes (SWCNTs) are fabricated for infrared (IR) detecting applications. Instead of thermal effect, quantum effect plays a dominant role in the sensing process. Under 0.3 mW/mm2 IR lamp illumination at 78 K in vacuum, the aligned device has a conductance increase as large as 68%, while the conductance of the network device increases 12%. Both devices perform much better than the SWCNT-polymer nanocomposites. Interestingly, at room temperature in the air, the photoresponse of the aligned device decreases compared to that in vacuum, while the network device performance boosts. We also test the devices in ambient argon, helium and nitrogen, respectively, similar results are achieved. Intertube junctions are considered to be responsible for the different behaviors. Our findings may pave a way for the design, fabrication, and packaging of low-cost and high-performance SWCNT-based IR sensors.