3-D Printed Instrumentation for Point-of-Use Leaky Waveguide Biochemical Sensor

Leaky waveguide (LW) biosensors enable accurate measurements using small sample volumes and are cheap to produce, and hence, are advantageous in the area of point-ofuse devices. Yet, current instrumentation to test LW chips is both bulky and costly because of the use of expensive components, such as glass optics, and manufacturing techniques, such as computer numerical control (CNC) machining. Meanwhile, 3-D printing allows the production of complex shapes that cannot be realized using these techniques, while injection molding allows the lowcost production of optical components. 3-D printed instruments offer huge advantages over traditional laboratory instrumentation, in terms of the cost of the manufacturing equipment required, the cost of the resulting instrumentation, size, and portability. This article describes the design and manufacture of a novel 3-D printed biosensor instrument and demonstrates its use for bioanalysis using LWs with a chitosan waveguide layer. This instrument has a refractive index (RI) resolution comparable to laboratory instrumentation and 3-D printed surface plasmon resonance (SPR) instruments [2.37 × 10
^-6
, 5.90 × 10
^-6
, and 1.7 × 10
^-6
RI units (RIUs), respectively] and has proven able to detect 133 nM (nmol L
^-1
) levels of immunoglobulin G (IgG) via the measurement of the change in resonance angle produced upon the protein binding to the film.