A process for integrated 3D trapping microcoil in microfluidic chips

Magnetic trapping with integrated microcoils in microfluidic circuits is limited by the poor magnetic field creation of the small coils compared to macroscopic coils or permanent magnets. In this paper, we present a new process using thick multilayers stacking and patterns transfer in order to obtain a high magnetic field into a microfluidic channel. The predicted magnetic field is up to 6 times higher than with a simple coil without magnetic material, forecasting a magnetic trapping capability raised by up to 30-50 times. We present here the manufacturing process and first results: an integrated microcoil with a quasi-closed magnetic circuit further featuring a microfluidic channel for the 1st time in the literature. The obtained performance is lower than the expected. However, the device opens the way to high performance integrated trapping devices.