We present the fabrication, characterization, use in cortical recording and histological results of a flexible implantable neural probe. The microfabricated device is implemented in polyimide and platinum providing mechanical flexibility, high quality electrical characteristics and excellent biocompatibility. Two layers of platinum electrodes are used which greatly reduces the size of the neural probes thereby limiting the insertion damage. The quality of the individual recording sites was characterized using impedance spectroscopy. In recording experiments, acute in vivo measurements were performed in the mouse cortex. Local field potential, single- and multi-neuron activities were simultaneously recorded. We demonstrate using immunohistochemistry techniques a study of the inflammation at the neural probe implantation site. We show that the major advantage of using polymer probes over silicon probes is the reduced damage due to insertion and probe-brain compliance mismatch.