Interdigitated microelectrodes biosensor with nanodot arrays for thyroid-stimulating hormone detection

Interdigitated microelectrodes (IDμE) are always used as the sensing structure of a biosensor to detect the hormone content in the human body. To increase the sensitivity of the IDμE biosensor, the authors provide an improved method that utilises IDμE with nanodot arrays, that is, the nanodot arrays are put into the inter-electrode gap in IDμE. The nanodot arrays can reduce the conducting distance between microelectrodes, thereby reducing the resistance to electricity and improve the sensitivity of biosensors. The improved biosensor is composed of IDμE and nanodot arrays: the IDμE is made by microelectro mechanical system (MEMS) technology, whereas the fabrication of nanodot arrays makes use of the nanosphere lithography (NSL) technology. Double Cr/Au bilayers are used to make a conjunction between the MEMS and NSL process. The biosensor based on the IDμE with nanodot arrays was used in the detection of low-level thyroid-stimulating hormone (TSH), and proved to provide about three times sensitive detection than the biosensor without nanodot arrays. The TSH detection limit of the biosensor based on the IDμE with nanodot arrays can reach 0.005 mIU/l. The improved biosensors can be used in the detection of other hormones, which are critical for disease intervention strategies.