期刊
SENSORS AND ACTUATORS A-PHYSICAL
卷 172, 期 1, 页码 117-123出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.sna.2011.02.052
关键词
Current sensing; ZeptoFarad capacitance detection; Nanosensor; Capacitive sensor; MEMS read-out; Lock-in amplifier
资金
- Fondazione Cariplo
- EU [228685-2]
The experimental detection of capacitance variations with a resolution as low as few zeptoFarads (10(-21) F) is presented. This is achieved by means of a CMOS ultra-low-noise and wide-bandwidth current sensing circuit, coupled to a lock-in amplifier to perform capacitance and conductance measurements in a frequency range from DC to 1 MHz. The adoption of an integrated implementation, based on an original circuital topology, provides miniaturization and performance improvement. The mm-sized chip can be easily integrated in extremely compact sensing setups. Resolution limits are analyzed in detail and experimentally investigated by means of a mechanical fixture that converts micrometric linear displacement into sub-aF capacitance steps. The experimental results match the theoretical expectation down to a resolution of 5 zF(rms) (6V at 100 kHz, with a 100ms time constant). The achieved current resolution of 15 fA(rms) (at similar to ms time scale) and the tracking of 40 zF capacitance steps demonstrate how the proposed read-out circuit can serve as a versatile tool for the development of nanosensors. (C) 2011 Elsevier B.V. All rights reserved.
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