Selective Electroless and Electrolytic Deposition of Metal for Applications in Microfluidics:  Fabrication of a Microthermocouple

Abstract

This paper describes a general strategy for the fabrication of a microthermocouple based on the spatially defined electroless deposition of metal, followed by annealing and electroplating. We present scanning electron microscopy and atomic force microscopy characterizations of the deposition and annealing process, as well as the performance of the microfabricated Ni-Ag thermocouple. The temperature-voltage curve for this Ni-Ag microthermocouple is linear over the range 0-50 degrees C with a slope of 61.9 degrees C mV(-1). The sensitivity of our temperature measurement, which is limited by the uncertainty of our calibration curve, is approximately 1 degrees C. The optimum figure of merit (Z(opt)) is 1.0 x 10(-5) for this type of Ag-Ni thermocouple. We have fabricated microthermocouples ranging in size from 50 to 300 microm. The microthermocouple was integrated into microchannels and used to measure the in-channel temperature rise caused by the following: (1) a simple acid-base reaction, HCl + NaOH --> H2O + NaCl, and (2) an enzyme-catalyzed biochemical reaction, H2O2 + catalase --> H2O + 1/2 O2. We have also profiled the temperature increase in the presence of electroosmotic flow for a 100-, 200-, and 300-microm channel.

Nickel Amperometric Detector Prepared by Electroless Deposition for Microchip Electrophoretic Measurement of Alcohols and Sugars

“…The HDV profiles are in agreement with the cyclic voltammograms (CV) of the two analytes (shown in the inset) at the electroless nickel detector (on the electrophoretic chip) in a 35 mM NaOH solution. The single anodic and two cathodic peaks found for the CV of ethanol and glucose are in good agreement to an earlier report [17]. These signals reflect the oxidation of Ni(OH) 2 to NiOOH and the reversed reduction to Ni(OH) 2 .…”

“…These signals reflect the oxidation of Ni(OH) 2 to NiOOH and the reversed reduction to Ni(OH) 2 . The two reduction waves correspond to the reduction of the coexisting and interconvertible b-NiOOH and g-NiOOH [17]. The electrochemically generated Ni(III) serves as the electrocatalyst for the oxidation of ethanol and glucose.…”

“…Both solutions were prepared daily owing to their rapid (24 h) degradation. The electroless nickel plating bath contained 40 g/L nickel(II) sulfate, 20 g/ L sodium hypophosphite, 100 g/L sodium citrate, and 50 g/L ammonium chloride [16,17]. The glass surface was cleaned before the electroless deposition by rinsing the end of the glass chip with ethanol, 0.1 M NaOH, and distilled water.…”

OLED Hybrid Integrated Polymer Microfluidic Biosensing for Point of Care Testing

“…The promising field of integrated MEMS (Micro Electro Mechanical Systems) involving microfluidics, Optical MEMS and microelectronics offers vast potential to realize low cost, efficient and reliable means for sensing and control in several application areas such as biotechnology, life sciences, pharmaceuticals, public health and defense [1][2][3]. This calls for a necessity to develop cost effective biosensor devices capable of rapid in-situ detection of biological elements.…”

Bio‐microfluidics: Biomaterials and Biomimetic Designs

“…[13][14][15][16] Despite this variety of potential applications, a major impediment to the evolution of these devices into mainstream technological impact use has been the limited material options that restrict both the nature of structures that can be realized and their applications. Currently, the majority of these devices are manufactured from materials used in the semiconductor industry, such as metals, [17] semiconductors, [18][19][20] and glasses. [21,22] These materials were selected due to their electronic compatibility and mature processing; however, they are generally difficult to chemically functionalize for biological and chemical sensitivity, and also generally require organic solvents or thermal processing for device manufacture.…”