Figure 1.

Design for TREM2 sensor chip based on plasmonic interferometry. (a) Cross-section schematic of the groove-slit-groove (GSG) architecture, which shows a slit flanked by two grooves, from which SPPs are excited by light diffraction and propagate towards the slit aperture, where they interfere and are then transmitted back into free space for far-field detection; diagram includes an example of an antigen complex, further described in Figure 2. The bottom slab represents quartz, the middle titanium, and the top layer gold. (b) Scanning electron micrograph (SEM) of a GSG interferometer with $p_1=7.65\mathsf{\mu }$m, $p_2=8.15\mathsf{\mu }$m. (c) Schematic of plasmonic interferometer sensor chip layout. The chip contains four nominally identical sensing spots enabling multiplex sensing applications. The yellow area indicates quartz covered by gold and the blank area is an uncoated quartz window used for optical alignment. (d) Schematic of a representative active sensing area. Each sensing area contains two columns of single slits and two columns of nominally identical asymmetric GSG interferometers with separation distance of 300 $\mathsf{\mu }$m. The slit/grooves in each interferometer are ∼20 $\mathsf{\mu }$m long and, within each column, the distance between two adjacent interferometers is ∼40 $\mathsf{\mu }$m.