Microelectromechanical probe for an integrated electroantennographic system

A microelectromechanical system (MEMS) probe for a miniaturized integrated system based on an electroantennographic technique is being developed for isolating and amplifying the nerve impulses that are superimposed on the receptor potential of a single sensillum hair on the insect's antenna. The ultimate aim of this work is to integrate this system onto a single silicon substrate, using both silicon surface micromachining technology and hybrid assembly techniques. The entire system comprises of two components: (a) a microelectromechanical probe; and (b) an ultra-low input bias current amplifier. Two types of probes have been developed. One based on the surface micromachining technology with an electrostatic actuation mechanism and the other one based on a simple glass capillary technique. These probes have been hybrid integrated with the ultra-low input bias current amplifier. The surface micromachined probe aims at penetrating its sharp polysilicon tip (cross-section of 2 by 2 /spl mu/m) into the base of sensillum hair to detect the nerve impulses, whereas the glass capillary works by placing it above an already cut-off tip of a sensillum hair. Here, the authors report on the results of their investigation on developing an appropriate design for the probe to be used in an integrated system which explores the potential use of the insect antenna as a biological sensor for pheromone study. The authors also show the selectivity and sensitivity of these biological sensors as compared to the one currently used in a conventional gas chromatography system.