A temperature-controlled chip holder with integrated electrodes for nanofluidic scattering spectroscopy on highly...

Fluidics on the micro- and nanoscale have been revolutionary for the fields of biology and medicine, and they are gaining a strong foothold in chemistry with the rise of micro and nanoscale reactors. These systems are based on fluidic platforms crafted into polymer or silicon-based substrates, and are comprised of channels with different functions and sizes that span from the micro- to the nanoscale. However, to fully capitalize on the possibilities offered by such highly integrated fluidic systems, the periphery that connects the fluidic chip to the macroscopic world, and thereby makes it accessible for the envisioned functions and applications, is equally important but receives much less attention. Such periphery needs to be versatile and enable accurate control of pressures and flow of liquids or gases, of sample temperature, and for certain applications even electric fields. Here, we report the development of a temperature-controlled fluidic chip holder for heating and cooling that is integrated with electrodes for the creation of electric fields across the fluidic system. It interfaces 1 cm² silicon-based nanofluidic chips with up to 12 fluidic connection points and optically transparent lid, that makes them compatible with optical microscopy techniques. We demonstrate the different functionalities of the sample holder by using nanofluidic scattering spectroscopy (NSS) to monitor the on-chip mixing of two different dyes, the diffusion of fluorescein into water at different temperatures, and the diffusion of fluorescein into water at different strengths of an electric field applied along a nanochannel.