A multilayered microfluidic system with functions for local electrical and thermal measurements

Abstract

Microfluidic systems have been extensively applied in research of chemistry, biology and fluidic dynamics. In these applications, local and precise measurements are often crucial for reliable results. We demonstrate here a multilayered, multifunctional microfluidic platform with embedded electrodes open to the microchannel and thermocouple sensors underneath the microchannel that are suitable for local electrical and thermal measurements, respectively. We demonstrate that precise transport measurements with ac excitation frequency up to 1 MHz can be performed for electrolytes in centimeterlong microchannels. Local temperature sensing of the fluids in the microchannels can also be performed on this system. Such system can be either used to characterize local electrical and thermal properties of fluids, or applied to the study of thermal related electrokinetic phenomena, such as joule heat generation in dc conductance or temperature dependence of electrical transport.

Performance of Nano-Submicron-Stripe Pd Thin-Film Temperature Sensors

“…The testing results showed that over an area of diameter 40–100 μm, the sensors could detect a weak surface temperature difference of 0.1–0.2 K. The merits of simple structure, stable performance, and compatible process to standard semiconductor techniques make the sub-micron sensors applicable in solid electronic devices, microfluidic systems, and even for bio-sensing at the cell level. For instance, it may detect local temperature distribution on an active electronic device with a better temperature resolution than what has been reported [ 33 ], or replace conventional thin-film thermocouples as the built-in sensor arrays in sophisticated lab-on-a-chip systems [ 34 ], and show better performance as they can also be fabricated with their sensing junctions open to the fluid channel [ 35 ].…”

Trapping and Driving Individual Charged Micro-particles in Fluid with an Electrostatic Device

“…Briefly, as schematically shown in Fig. 2 b, a Ti/Au film (5/100 nm) was patterned on a 4″ glass wafer by photolithography (Instrument: SUSS, MBJ4), coating process (Instrument: Kurt J. Lesker, PVD 75), and lift-off process to function as the electrodes [ 59 ]. Then, a 300-nm-thick spin-on-glass (SOG) (Futurrex, Inc, China) was spin-coated on the wafer as the dielectric layer.…”

Thermophoretic Micron-Scale Devices: Practical Approach and Review

“…The accuracy of a thermocouple of is one order of magnitude better than for RTDs and the actual voltage measurement is straightforward. Additionally, using cleanroom facilities, it is possible to reduce the size of the junction (measuring point) to 0.1 m [ 105 , 106 , 107 ]. However, the voltage level is rather low, so that external electric fields can induce some noise.…”