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. Author manuscript; available in PMC: 2020 Dec 1.
Published in final edited form as: Anal Biochem. 2019 Sep 4;586:113414. doi: 10.1016/j.ab.2019.113414

Figure 1.

Figure 1.

(A) Design of 3D printed three-channel centerpiece with sector angles of 2.2°, filling and venting holes, dome-shaped ceilings, and embossed rims surrounding the sectors that serve as integrated gaskets for vacuum seal. (B) Photographs of centerpieces 3D printed in an epoxy-like photopolymer “MicroFine Green” (ProtoLabs, Maple Plain, MN) using modification of a design file 3DPX-010758 of the NIH 3D Print Exchange (3dprint.nih.gov). Shown are centerpieces with 4 mm (left) and 12 mm pathlength (right), respectively. (C) Principle of illumination modes of three-channel centerpieces with Rayleigh interference optical detection. Two coherent parallel planar beams traverse either the left and the middle sector (left sketch), or the right and the middle sector (right sketch). The middle sector contains a joint reference buffer (blue), such that in the left configuration the purple sample can be observed, and in the right configuration the green sample can be observed. The two configurations have a 3-4° different rotation angle at the time of data acquisition, and due to the reversed beams they differ in the sign of the fringe shift signal.