Available Technology

Attenuated total reflection flow cell

This invention uses prisms to couple infrared radiation into a double-side polished wafer that serves as the internal reflection element (IRE) for attenuated total reflection (ATR) spectroscopy using a flow cell. ATR flow cells are used for flow chemistry, biology/biotech, electrochemistry, photochemistry, heterogeneous catalysis, surface science, environmental chemistry, research, quality control, and process monitoring. In the commercial market they are based on crystals (e.g., zinc, selenide and germanium). Unfortunately, these crystals must be removed from the flow cell, cleaned, polished and replaced in the flow cell oftentimes when new substances are introduced into the spectroscopy experiment. IREs typically cost $500 commercially and because of the high cost of IREs, the analytes and experiments are limited to those that do not damage or irreversibly alter the IRE, which must be treated as a reusable item.

This new invention is an improvement over these commercial products due to its use of inexpensive disposable silicon wafers as the contact with the flowing material. Double-side polished float zone silicon and sapphire wafers cost around $20. This low price results in lower prices of each experimental run and makes many possible experiments feasible. Additionally, the wafers are semi-disposable and can be modified irreversibly, which allows greater flexibility in developing experiments and especially those that involve in-situ measurements of liquid-phase processing.


A double-sided polished wafer that is transparent to infrared radiation is coupled to two reusable prisms of high refractive index by applying localized pressure. By coupling the prism to the wafer, infrared radiation at an angle greater than the critical angle can be passed through the wafer with multiple internal reflections. One of the wafer surfaces is sealed to create a flow channel for either analytes or process fluids to be introduced. The opposite surface is supported, which provides a normal force for the sealing and a means to heat the wafer. Prior to infrared measurements the wafer may be processed irreversibly for the purpose of the measurement. After infrared measurements, the wafer can be analyzed with ex situ methods or further processed.


Brent Sperling

Patent Number: 
Technology Type(s): 
Analytical Chemistry, Materials, Materials Physics and Chemistry, Biochemical Science, Biomaterials, Chemical Science, Physical and Chemical Properties, Process Improvement, Surface and Microanalysis Science,
Internal Laboratory Ref #: 
Patent Issue Date: 
February 20, 2018
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