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Micro-Opto-Electro-Mechanical resonant micromirror featuring a 4 mm aperture for laser-based measurement is presented. The MOEMS-mirror is fabricated on an SOI-wafer with piezoelectric actuators based on aluminium nitride thin films and packaged in a vacuum for a high-efficiency operation. The design of the device features four symmetrical co-radial beam structures, where each beam structure incorporates discrete piezoelectric elements for actuation and sensing. The integrated sensing element provides an accurate and real-time feedback signal for the control system, as it is directly mechanically coupled to the source of movement. Symmetrical design allows the mirror to be excited in the desired mode by modifying the frequency and phase on each of the driving actuators. For the laser measurement applications driving the mirror opposite actuators in opposite polarity and perpendicular axis with different frequencies, creates up to a 40-degree field of view Lissajous scanning pattern. The amplitude of the resonance is strongly affected by the Duffing-type nonlinearity and the derivative of the amplitude vs. frequency curve is small, allowing relatively large changes of frequencies without affecting the amplitude. Phe presented digital control method allows adjustment of frequencies via a phase accumulator to control Lissajous pattern parameters: ratio, phase and amplitude. Due to the high efficiency of aluminium nitride actuators and high Q value, a direct low-voltage CMOS interface can be implemented between the digital control system and piezoelectric actuators. The high amplitude feedback signals allow straightforward conversion to the digital domain and enable monitoring of operation mode and phase.

Two novel RF MEMS power sensors operating up to 5 GHz and 45 GHz respectively have been designed. The lower frequency device is a coplanar transmission line with released ground sections. The rms voltage across the conductors causes the released ground lines to bend towards the signal line in the middle. This bending can be detected capacitively with a pair of sense electrodes. The higher frequency device extends a Si plate, which is metallized underneath, above a coplanar transmission line. The electrostatic force due to the rms voltage pulls the Si plate towards the transmission line, which can again be detected with a pair of sense electrodes. Microwave simulations indicate that input match better than -30 dB and transmission loss less than 0.2 dB up to 45 GHz can be achieved. For the 5 GHz design a power resolution of -39 dBm and -37 dBm for the 45 GHz design have been obtained by analysis. Measured results for the first generation 5 GHz device show input match better than -15 dB and transmission loss less than 0.7 dB. Measured results from the 45 GHz device do not exist yet.

Uuden sukupolven pienemmät ja tarkemmat MEMS-anturit tulevat korvaamaan nykyiset anturit halvempien tuotantokustannusten ansiosta. MEMS-komponenttien hinnasta jopa 80% voi koostua testaus- ja kalibrointikustannuksista. Uudet tarkkuussanturit voidaan ottaa käyttöön huomattavasti kevennetyllä testausmenettelyllä. Lisäksi parantuneen suorituskyvyn ansiosta stabiileille MEMS-komponenteille avautuu uusia sovellusmahdollisuuksia esimerkiksi tarkkuusinstrumentoinnin alalta.

A novel inline type millimeter wave MEMS power sensor is presented. The electrostatic force due to the ms voltage across the transmission line conductors displaces the sensor electrode, and the movement can be detected capacitively. RF properties of the sensor can be optimized so that S11 is better than -30 dB and S21 less than 0.1 dB up to 45 GHz with a power resolution of -37 dBm.

A novel inline type millimeter wave MEMS power sensor is presented. The electrostatic force due to the rms voltage across the transmission line conductors displace the sensor electrode, and the movement can be detected capacitively. The modelling of the sensor shows that it has S11 better than -30 dB up to 32 GHz with a power resolution of -28 dBm.

Piezoelectrically actuated resonant micromirrors were designed to meet the light detection and ranging (LiDAR) system requirements. Key features were a 3-mm mirror aperture, a 40-deg field of view, and a 50-Hz refresh rate. The presented micromirror provides biaxial symmetrical beam steering with ±12.7 deg mechanical tilt angle, resulting in a 50-deg field of view with an adjustable Lissajous XY-scanning pattern for a forward-looking LiDAR system. The mirrors were fabricated using silicon on insulator wafers, and actuation was based on piezoelectric aluminium nitride thin film. The mirrors were vacuum packaged for high-quality factor resonator operation. The device design contained eight separate piezoelectric aluminium nitride elements arranged as differential pairs for each axis, where each actuator was equipped with a sensing element providing a mechanically coupled electrical feedback signal. The piezoelectric elements connected as actuators required only minimal power and were directly compatible with CMOS low-voltage logic, which eases integration to driving digital systems. The sense elements are used to monitor phase, amplitude, and frequency. A digital control system connected to each of these elements provides accurate frequency and phase control of independent orthogonal resonators, permitting control of the X and Y amplitudes and the refresh rate of the Lissajous pattern.