Poly(dimethylsiloxane) hollow Abbe prism with microlenses for detection based on absorption and refractive index shift

Abstract

In this paper we report on an optical detection method that utilizes two physical effects for signal transduction, namely absorption and shift of refractive index. The device consists of a hollow prism and was fabricated by means of soft-lithography. It exhibits a high degree of monolithic integration. In order to keep down the amount of external equipment that is necessary to run the device, we were able to integrate several functions, such as focussing of light and alignment of optical fibres. Since all components are fabricated in the same material and in the same process, compatibility with other microfluidic devices or components can be achieved easily. The functional efficiency and the performance of the detector were tested by investigating solutions containing fluorescein, with concentrations between 5 and 1000 microM. The results clearly show the two regions in which the two physical effects are effective.

Integrated Indium Micromirrors for Optofluidics

“…Furthermore, the mirrors were designed with a concave shape to re-focus the light in order to solve the problem of dispersion. Source: [13][14][15] As it can be observed, this latest improvement leads to a single-step fabricated portable device that can perform high-sensitivity measurements with low amount of analyte. That is, a device that meets the already set up requirements of monolithic integration, ubiquity, cheap fabrication and few sample needs.…”

“…Each one of the following methods is just one step more to its previous version. a) PDMS hollow Abbe Prism [13]: A prism shaped microfluidic cavity was designed to take profit of the change of refractive index between air (or the analyte) and the PDMS walls. This would allow redirecting the light beam back to the cavity and thus, increment the optical path length.…”

Unconventional detection methods for microfluidic devices

“…Picture of the system used, displaying the input/output PDMS biconvex lens, the optical fibres, and the Abbe prism filled with buffer solution 1 50 mM fluorescein. Reprinted with permission from [94].…”

“…The system was seen to be useful in on-line reaction monitoring in microfluidic environments. Llobera et al [94] designed an RI detector that consisted of a hollow Abbe prism with microlenses fabricated on PDMS, as shown in Fig. 8.…”

Biofunctionalized all-polymer photonic lab on a chip with integrated solid-state light emitter

“…One first step toward tackling this issue is to define self-alignment microchannels for the clamping and positioning of fiber optics. 25 Although effective, this approach requires trained users and special tools to define high-quality fiber optic facets, not to mention their inherent fragility. The optimal configuration would be to have a disposable light source directly implemented (and hence aligned) in the PhLOC.…”