Polyimide, a new shielding layer for sensor applications

In sensor applications it is often necessary to cover the sensor surface or the interacting area of the sensor with a shielding layer. We present a well reproducible and easy method to shield a sensor surface with an aromatic polyimide layer. The shielding capacity was tested with surface acoustic wave (SAW) devices which are commercially available and furthermore meet the requirements for (bio)sensor applications in aqueous media. All experiments described here were done with these devices. One major advantage of this technique was the prevention of corrosion processes on the sensor surface, especially the damage of interdigital transducers which often consist of aluminium, because this material is known to have the best acoustoelectric properties for SAW-devices. Besides, we show that a thin polyimide film enhance the typical sensor characteristics in terms 'of sensitivity and stability'. (C) 1998 Elsevier Science S.A. All rights reserved.