Monolithically Integrated Diffused Silicon Two-Zone Heaters for Silicon-Pyrex Glass Microreactors for Production of Nanoparticles: Heat Exchange Aspects

Abstract

We present the design, simulation, fabrication and characterization of monolithically integrated high resistivity p-type boron-diffused silicon two-zone heaters in a model high temperature microreactor intended for nanoparticle fabrication. We used a finite element method for simulations of the heaters’ operation and performance. Our experimental model reactor structure consisted of a silicon wafer anodically bonded to a Pyrex glass wafer with an isotropically etched serpentine microchannels network. We fabricated two separate spiral heaters with different temperatures, mutually thermally isolated by barrier apertures etched throughout the silicon wafer. The heaters were characterized by electric measurements and by infrared thermal vision. The obtained results show that our proposed procedure for the heater fabrication is robust, stable and controllable, with a decreased sensitivity to random variations of fabrication process parameters. Compared to metallic or polysilicon heaters typically integrated into microreactors, our approach offers improved control over heater characteristics through adjustment of the Boron doping level and profile. Our microreactor is intended to produce titanium dioxide nanoparticles, but it could be also used to fabricate nanoparticles in different materials as well, with various parameters and geometries. Our method can be generally applied to other high-temperature microsystems.

Transesterification of Sunflower Oil over Waste Chicken Eggshell-Based Catalyst in a Microreactor: An Optimization Study

“…Some novel reactors, such as microchannel reactors, have been developed to achieve high mixing performance and improve mass transfer and, therefore, increase reaction yield [ 11 ]. Microreactors present microfluidic systems in which chemical reactions are performed in a controlled manner within a network of microchannels (widths and depths range from tens to hundreds of micrometers), where the fluid flow is laminar and mass and heat transfer are strongly enhanced [ 12 , 13 ]. These reactors have been shown to be suitable for optimization of many heterogeneously-catalyzed synthetic procedures because of their positive effect on transfer phenomena in the overall reaction, like glucose oxidation, Knoevenagel condensation, alkene epoxidation, enzymatic hydrolysis, esterification, etc.…”

Design of a Microfluidic Photocatalytic Reactor for Removal of Volatile Organic Components: Process Simulation and Techno-Economic Assessment

“…Pyrex is highly suitable for photocatalytic MRs, as it has good chemical stability and transparency over a broad range of wavelengths. 17 Pyrex and its fabrication costs are also considered inexpensive. 18 The cost of the Pyrex glass attached to the UV-LED was considered to be part of the MR cost.…”

“…It was assumed that the microdevice is made of stainless steel with a transparent side made of Pyrex glass lid in contact with an array of UV-LED lights to activate the catalyst thin film immobilized in all the microchannels. Pyrex is highly suitable for photocatalytic MRs, as it has good chemical stability and transparency over a broad range of wavelengths . Pyrex and its fabrication costs are also considered inexpensive .…”

Editorial for the Special Issue on Micro-Manufacturing and Applications

“…The process of etching for the production of micro and nano features or particles is, again, a very important part of this paper selection, demonstrating the use of Integrated Diffused Silicon Two-Zone Heaters for Silicon-Pyrex Glass Microreactors for Production of Nanoparticles [ 7 ]. The obtained results show that the proposed procedure for the heater fabrication is robust, stable, and controllable, with a decreased sensitivity to random variations of fabrication process parameters.…”