title: A single-layer, planar, optofluidic Mach-Zehnder interferometer for label-free detection.
abstract: We have developed a planar, optofluidic Mach-Zehnder interferometer for the label-free detection of liquid samples. In contrast to most on-chip interferometers which require complex fabrication, our design was realized via a simple, single-layer soft lithography fabrication process. In addition, a single-wavelength laser source and a silicon photodetector were the only optical equipment used for data collection. The device was calibrated using published data for the refractive index of calcium chloride (CaCl(2)) in solution, and the biosensing capabilities of the device were tested by detecting bovine serum albumin (BSA). Our design enables a refractometer with a low limit of detection (1.24 × 10(-4) refractive index units (RIU)), low variability (1 × 10(-4) RIU), and high sensitivity (927.88 oscillations per RIU). This performance is comparable to state-of-the-art optofluidic refractometers that involve complex fabrication processes and/or expensive, bulky optics. The advantages of our device (i.e. simple fabrication process, straightforward optical equipment, low cost, and high detection sensitivity) make it a promising candidate for future mass-producible, inexpensive, highly sensitive, label-free optical detection systems.
authors.affiliation: Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Michael Ian
authors.initials: MI
authors.lastname: Lapsley
authors.forename: I-Kao
authors.initials: IK
authors.lastname: Chiang
authors.forename: Yue Bing
authors.initials: YB
authors.lastname: Zheng
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Ding
authors.forename: Xiaole
authors.initials: X
authors.lastname: Mao
authors.forename: Tony Jun
authors.initials: TJ
authors.lastname: Huang
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D002122:Calcium Chloride / Q000737:chemistry; D002417:Cattle; D007368:Interferometry / Q000295:instrumentation* / Q000379:methods; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods; D012710:Serum Albumin, Bovine / Q000737:chemistry
chemical_list: D012710:Serum Albumin, Bovine; D002122:Calcium Chloride