We present an electromagnetically driven microscanner based on a gimbal-less twist mechanism. In contrast to conventional microscanners using a gimbal-less leverage mechanism, our device utilizes a gimbal-less twist mechanism to increase the scan angle in optical applications requiring a large scanning mirror. The proposed gimbal-less scanner with twist mechanism increases the scan angle by 1.55 and 1.97 times for the slow and fast axes, respectively, under the same force; 3.64 and 1.97 times for the slow and fast axes, respectively, under the same maximum stress, compared to the gimbal-less leverage mechanism. The scanner with a 3-mm-diameter mirror and a current path composed of a single-turn coil was fabricated, and it showed the maximum scan angle of 5° (quasi-static) and 22° (resonant) for the slow and fast axes, respectively. The experimentally estimated crosstalk was as small as 0.47% and 0.97% for the fast and slow axes affected by the other axes, respectively, which was determined using a newly employed methodology based on fast Fourier transform.

This paper describes an input shaping method based on an experimental transfer function to effectively obtain a desired scan output for an electrostatic microscanner driven in a quasistatic mode. This method features possible driving extended to a higher frequency, whereas the conventional control needs dynamic modeling and is still ineffective in mitigating harmonics, sub-resonances, and/or higher modes. The performance of the input shaping was experimentally evaluated in terms of the usable scan range (USR), and its application limits were examined with respect to the optical scan angle and frequency. The experimental results showed that the usable scan range is as wide as 96% for a total optical scan angle (total OSA) of up to 9° when the criterion for scan line error is 1.5%. The usable scan ranges were degraded for larger total optical scan angles because of the nonlinear electrostatic torque with respect to the driving voltage. The usable scan range was 90% or higher for most frequencies up to 160 Hz and was drastically decreased for the higher driving frequency because fewer harmonics are included in the input shaping process. Conclusively, the proposed method was experimentally confirmed to show good performance in view of its simplicity and its operable range, quantitatively compared with that of the conventional control.

ENN (electrical impedance spectroscopy on-a-needle with non-passivation) can be used to discriminate bio-tissues based on depth-profiling. Since the ENN electrodes are comprised of a detection and connection parts, electrical impedance on the connection part tends to cause a distortion in the sensor output depending on the penetration depth. This distortion leads to an inaccurate evaluation of the electrical properties (conductivity and permittivity). In order to attenuate the distortion, two methods were proposed in previous studies as follows: ENS (electrical impedance spectroscopy on-aneedle with selective-passivation on the connection part) and ENNI (ENN with incremental compensation method). In this study, we compared the detection error between the two proposed methods in terms of the depth-profiling for threelayered porcine tissues. To evaluate the detection error of the aforementioned methods, the electrical properties obtained by the two methods were compared against reference values obtained directly from the side of the tissues penetrating only detection part. In the case of ENS, the detection errors of conductivity and permittivity were 3.86 % and 3.25 %, respectively, while for ENNI, the detection errors were 10.50 % and 4.57 %, respectively. Thus, despite involving a complicated fabrication process, ENS is expected to more useful than ENNI for the characterization of biotissues.