Novel piezoresistive e-NOSE sensor array cell V.Stavrov, P.Vitanov, E.Tomerov, E.Goranova, G.Stavreva

Future of analytical and manufacturing methods based on micro-mechanical cantilevers, depends critically on the ability to implement parallel operation and fast signal processing [1]. There are two mean reasons: high throughput requirement and complexity (multidimensionality) of analyzed value. In order to get parallel function, any single device should be simultaneously: recognizable, autonomously actuated and independently accessible for readout. Devices, fulfilling these requirements, are suffering from a substantial increase in complexity of both layout and manufacturing technology. In present paper, we demonstrate a novel design of a MEMS (Micro-Electro-Mechanical Systems) cell designed for e-NOSE applications, using results of previous works [2,3], which solves above mentioned problems. The cell consists of four integrated cantilevers, each having a separate piezoresistor. Additionally, the cantilevers are designed to be different in length and thus having different resonance frequencies. Thus, individual cantilevers are frequency recognizable/addressable. Samples of self-actuated piezoresistive cantilever sensor have been fabricated on n-type, <100> silicon, applying combined surface and bulk micromachining techniques. The cantilever dimensions were chosen to provide approx. 1.8 kHz resonance frequency gap between neighbor individual sensors. The new micro-machined cell is suitable for chemical and biological recognition as a micro-balance.