Discharging-phototransistor-integrated high-voltage Si photovoltaic cells for fast driving demonstration of an electrostatic MEMS actuator by wavelength modulation

Abstract

In this article, the authors propose a high-voltage photovoltaic (PV) cell array integrating discharging phototransistors for the fast driving of an electrostatic MEMS actuator by light with wavelength modulation. A PV cell array and phototransistors are connected in parallel and colored with green and red lacquer, respectively. This circuit repeats the charge and discharge of a MEMS actuator by being illuminated with light whose color periodically changes between red and green. This method requires only a small additional area and can discharge the actuator at an arbitrary timing. The authors extract the parameters of the circuit and also demonstrate the dynamic driving of a MEMS comb-drive actuator.

Integration of a CMOS LSI Chiplet into Micro Flexible Devices for Remote Electrostatic Actuation

“…We adopted the deep trench isolated PV cells and PTs reported by Mori et al [6]. Charge and discharge are remotely controllable by the color of light due to the builtin color-selective phototransistor.…”

Progress and opportunities in high-voltage microactuator powering technology towards one-chip MEMS

“…14. Application circuits and demonstration devices include cascadable 30 V high-voltage switching circuits, 60) wavelength-multiplexed, optically powered remote turn-on-and-off operation of comb drive resonators 61) and wavelength-multiplexed, optically commanded HV drivers. 62) In the latter two examples, a parasitic bipolar junction transistor (BJT) composed of the P-diffusion, N-well, and P-substrate was used to induce larger photocurrents.…”

“…The PNP transistor had a current gain of β ≈ 10 and a breakdown voltage of approximately 50 V. By painting the series PV cells in green, and PNP BJT in red, alternate illumination of green and red LEDs successfully charged and discharged a connected comb drive actuator. 61) In HV applications, 62) two BJTs connected the gate-source and gate-drain, to turn on and off the gates of series-connected transistors by color-coded optical commands. Such a configuration works as long as no breakdown occurs.…”

A scalable, optically-driven, high-voltage switch for remote MEMS device operation fabricated with a standard CMOS process

“…Fig. 2 shows one of the devices fabricated in the method explained in the authors' previous work [13]. That is, an SOI wafer delivered from the CMOS foundry was post-processed to mesa-isolate the n-MOSFETs and the phototransistors with anisotropic and isotropic plasma etching, followed by the painting of lacquer in red and green.…”

“…In this paper, we propose a high-voltage switch for remote MEMS device operation driven by wavelength-modulated light [12], which employs the method of circuit function switching that we previously proposed [13]. By controlling the switch with light instead of electricity, we eliminate complex voltage level shifters, which achieves high-voltage switching with small number of transistors that are fabricated with a standard CMOS process.…”