Yuju Lu

Low-temperature bonding of poly-(methyl methacrylate) microfluidic devices under an ultrasonic field

High bond strength at low temperature without shape distortion is a major goal in microfluidic device fabrication. In this paper, we present a new easy bonding method for poly-(methyl methacrylate) (PMMA) microdevices at low temperature in an ultrasonic field. The ultrasonic energy spot effect at an interface could lead to a high bond strength up to 30 mJ cm−2 at only 60 °C. This bond strength is tens of times higher than the typical value in the literature (Tsao et al 2007 Lab. Chip. 7 499). The benefit from the low bonding temperature is that no deformation of the channel was evident. Few changes in the substrate surface property were observed. The static water contact angle of the bonded substrates had a small decrease compared to that of the virgin ones. The bonded microchannel devices were not reduced in transparency and smoothness. This method is batch-production oriented because many microdevices could be bonded at one time.

Two‐Phase Electro‐Electrodialysis with an Emulsion as Anolyte

Abstract A new technique of two‐phase electro‐electrodialysis process has been developed and applied to separate acetic acid from its solution. Normally an aqueous phase is applied as the anolyte solution in a normal electro‐electrodialysis process. In the new technique an emulsion composed of 49.9% kerosene, 49.9% water, and 0.2% Tween was used as the anolyte instead of the aqueous phase. The influences of the electrical current and the initial anolyte and catholyte concentration on the performance of the normal or the new process have been studied. The experimental results showed that the new technique could control the electroosmosis and osmosis effectively. Almost no anolyte volume change has been observed during the two‐phase electro‐electrodialysis process. And also much higher concentrated ratio with almost 100% recovery can be reached with the new technique. In the process, the electrical current efficiency was kept around 50%. Furthermore it was found that the concentration difference between the anolyte and the catholyte has less influence in the two‐phase electro‐electrodialysis process than that in the normal electrodialysis process.