No abstract

In the past few years, there has been increased interest in the development and applications of hydrogel nanocomposites, specifically as a new class of biomaterials. In some cases, the nanoparticles (e.g., gold, magnetic, carbon nanotubes) can absorb specific stimuli (e.g., alternating magnetic fields, near-IR light) and generate heat. This unique ability to remotely heat the nanocomposites allows for their remote controlled (RC) applications, including the ability to remotely drive the polymer through a transition event (e.g., swelling transition, glass transition). This review highlights some of the recent studies in the development of the RC hydrogel nanocomposites. In particular, some of the important applications of RC nanocomposites as RC drug delivery devices, as RC actuators, and in cancer treatment are discussed.

No abstract

No abstract

In recent years, hydrogels have attracted attention as active components in microfluidic devices. Here, we present a demonstration of remote controlled flow regulation in a microfluidic device using a hydrogel nanocomposite valve. To create the nanocomposite hydrogel, magnetic nanoparticles were dispersed in temperature-responsive N-isopropylacrylamide (NIPAAm) hydrogels. The swelling and collapse of the resultant nanocomposite can be remotely controlled by application of an alternating magnetic field (AMF). A ceramic microfluidic device with Y-junction channels was fabricated using low temperature co-fired ceramic (LTCC) technology. The nanocomposite was incorporated as a valve in one of the channels of the device. An AMF of frequency 293 kHz was then applied to the device and ON-OFF control on flow was achieved. A pressure transducer was placed at the inlet of the channel and pressure measurements were done for multiple AMF ON-OFF cycles to evaluate the reproducibility of the valve. Furthermore, the effect of the hydrogel geometry on the response time was characterized by hydrogels with different dimensions. Magnetic hydrogel nanocomposite films of different thicknesses (0.5, 1, 1.5 mm) were subjected to AMF and the kinetics of collapse and recovery were studied.