Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

CMOS-integrated four-channel resonant cantilever array

The four-channel resonant cantilever system features an array of four equally-spaced cantilevers with a pitch of 500 µm. The actuation, as well as the read out scheme is integrated on the cantilevers, which allows fully autonomous operation. Hence, no external read out equipment, such as a laser setup is needed. The cantilevers are electromagnetically actuated using the Lorentz force acting on an integrated current path in a static external magnetic field.

The cantilever vibration is read out by a transistor-based Wheatstone bridge, which is located at the clamped edge of the cantilever. Monolithically integrated on the same chip are a multiplexer, an analog feedback circuit and a digital I2C bus interface. All four cantilevers can be sequentially connected via the multiplexer to the analog feedback circuit, thus serving as frequency-determining element in an oscillator configuration. The chip size is 4.8×2.6 mm2.

With the integrated multiplexer it is possible to operate and read-out all four cantilevers sequentially. This allows, for instance, to quantify multiple analytes simultaneously in a sample. An upgrade to a larger sensor array is possible.
The sensor is fabricated in a standard 0.8-µm CMOS process and the cantilevers are released with dedicated post-CMOS micromachining. A special chip package based on the casting of poly(dimethylsiloxane) (PDMS) was developed, which allows the operation of the cantilever chip in liquid environments. The sensor has been used to detect prostate specific antigen (PSA) levels as low as 10 ng/ml in sample fluids.

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Reported by

ETH Zürich
HPT H6, ETH Hönggerberg
8093 Zürich
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