A spectroelectrochemical study on perylene cation radical in polymer microchannel-microelectrode chips

Abstract

Polymer microchannel chips (depth 20 microm and width 100 microm) integrated with band electrodes were fabricated by photolithography and imprinting methods, and applied to a spectroelectrochemical study on the cation radical of perylene (Pe). A propylene carbonate solution of Pe was brought into the channel chip by pressure driven flow and Pe was oxidized at the working band electrode (WE) in the channel. Simultaneously, absorption measurements of the solution phase in the downstream side of the electrode (30 microm from WE) were conducted on the basis of space resolved spectroscopy. The decrease in the absorbance of Pe at 438 nm upon electrolysis accompanied an appearance of the absorption band around 538 nm, which was assigned to that of the Pe cation radical. When the perylene solution was introduced to the microchip at a slow flow velocity, the dimer cation radical of Pe was shown to be produced in the channel chip. The formation and disappearance processes of the monomer and dimer cation radicals of Pe in the channel were followed by flow velocity and position dependencies of the absorption spectra.

Polymer Channel Chips as Versatile Tools in Microchemistry

“…1c. [13][14][15][16][17][18] Typically, a thin metal film (Pt, Au, or Ag) is deposited directly onto a PSt substrate in vacuum and the structure of a microelectrode/microheater on the PSt substrate is fabricated by photolithography/etching of the metal layer. The microelectrode/ microheater is then buried into the PSt substrate by pressing the substrate between two glass plates at 108˚C.…”

“…3. [13][14][15][16][17][18] For spectroscopic measurements, incident light from an Xe lamp or laser is introduced to an optical microscope through an objective lens and irradiated to the sample solution in the microchannel chip placed on the stage of the microscope: irradiated spot size = 2 -3 mm. For absorption spectroscopy, transmitted light passed through the sample solution is reflected by a half mirror set below the microscope stage and introduced to a photodetector to record an absorption spectrum.…”

“…By combining a microchannel-microelectrode chip with an absorption microspectroscopic technique, furthermore, one can conduct spectroelectrochemical experiments as described later in detail. 16 In these experimental modes, spatially-resolved measurements under solution flow conditions provide invaluable information about phenomena proceeding in a microchannel chip. As an example, solution mixing processes started at the junction of two microchannels can be followed by spatially-resolved absorption/emission spectroscopy along with solution flow to the downstream side of the junction.…”

“…16 So far, a spectroelectrochemical study has been conducted by using an optically transparent thin layer electrochemical cell. 31 In such a study, a thin metal mesh WE placed between two transparent glass plates is immersed in a sample solution and the solution is introduced to the glass cell by capillary action.…”

Raman Microspectroscopy/Imaging Study on Phase-Vanishing Processes of Fluorous Biphase Systems in Microchannel-Microheater Chips

“…It is now widely recognized that chemical reaction, separation, and/or detection systems can be integrated on a single microchip and that various chemical operations can be conducted along solution-flow in a microchannel. [12][13][14][15][16][17][18][19][20][21][22][23] A microchannel-microheater chip has been also reported. In a minute space such as in a microchannel integrated with a heater, local cooling/heating proceeds very quickly owing to large surface area/volume ratios of both microheater and michrochannel.…”