Effect of Joule heating on efficiency and performance for microchip‐based and capillary‐based electrophoretic separation systems: A closer look

Abstract

An attempt is made to revisit the main theoretical considerations concerning temperature effects ("Joule heating") in electro-driven separation systems, in particular lab-on-a-chip systems. Measurements of efficiencies in microfabricated devices under different Joule heating conditions are evaluated and compared to both theoretical models and measurements performed on conventional capillary systems. The widely accepted notion that planar microdevices are less susceptible to Joule heating effects is largely confirmed. The heat dissipation from a nonthermostatically controlled glass microdevice was found to be comparable to that from a liquid-cooled-fused silica capillary. Using typically dimensioned glass and glass/silicon microdevices, the experimental results indicate that 5-10 times higher electric field strengths can be applied than on conventional capillaries, before detrimental effects on the separation efficiency occur. The main influence of Joule heating on efficiency is via the establishment of a radial temperature profile across the lumen of the capillary or channel. An overall temperature increase of the buffer solution has only little influence on the quality of the separation. Still, active temperature control (cooling, thermostatting) can help prevent boiling of the buffer and increase the reproducibility of the results.

Zone Electrophoresis in an Inner-cooling Wide-bore Electrophoresis System with UV Detection

“…It indicates that the WE system generates much more Joule heat, which is in direct ratio to the effective cross section area, A. If this Joule heat cannot be dispersed in time, excessive heat will result in a temperature gradient in the radial channel, and consequently cause serious problems, such as sample zone broadening [20][21][22] and, even worse, stopping the separation process. Therefore, the configuration of the shell-and-tube heat exchanger was introduced into the WE system to enhance the dispatching of heat in situ in real time.…”

Rapid detection of low-abundance K-ras mutation in stools of colorectal cancer patients using chip-based temperature gradient capillary electrophoresis

“…In contrast, if the ratio of surface area to the volume of the channel of the chip-based CE is higher, joule heating is released easily, and higher field can be used to achieve improved resolution, which in turn leads to an excellent separation of homoduplexes and heteroduplexes in TGCE. 42,43 Second, according to the separation principle of TGCE, the resolution efficiency for mutant DNA fragments is dependent on the temperature melting profile of the detected sequences. If the mutant sequence is located in the lowmelting domain in a whole DNA fragment, the migration differences between heteroduplexes and homoduplexes during CE are readily produced and retained.…”

Monolithic integration of fine cylindrical glass microcapillaries on silicon for electrophoretic separation of biomolecules

“…For instance, trench 5 as compared to trench 8 has a larger angle of expansion (2.3 > 0. 9 ) and yet cannot be always filled, as its termination width is slightly narrower (5 lm < 6 lm). To test whether the filling can be facilitated by suction, reservoir BW was connected to a vacuum pump with the remaining reservoirs left open to the atmosphere.…”

“…A mixture of FITC-labeled three amino acid molecules (Ser, Gly, and Gln) was loaded into a representative device in which five out of ten microcapillaries (6)(7)(8)(9)(10) were filled with the running buffer. Their electropherograms obtained at the detection point (1 mm from reservoir BW) are shown along with a fluorescence image of the microcapillaries in Fig 5(a).…”

“…CE, particularly lCE, owing to a high surface-to-volume ratio (SVR) of a small capillary or a planar microchannel, removes heat much quicker than the traditional slab-gel electrophoresis, and tolerates much larger field strengths, thereby achieving a higher separation speed and resolution. 9 Still, the experiments with the lCE devices suggest that the heat removal efficiency may not be adequate to avoid performance degradation at higher voltages. [10][11][12] Some of these devices make use of glass or polymer substrates, which may not be that effective in heat removal.…”