research | from fundamentals to action





RF MEMS is one of the focused R&D areas of the MEMS program, which targets to provide solutions for multi-standard, multi-mode RFIC systems. IME has demonstrated a 32kHz resonator for real time oscillator, AlN checker mode resonator for GHz range oscillator and filter and tunable capacitor for impedance tuner.

32kHz resonator

A frequency-drift resilient method was applied to design a lateral capacitive MEMS resonator to make its resonant frequency insensitive to the process-induced variation. The resonant frequencies are in the range of 32102±25Hz and obey basically the normal distribution. The drift from designed value is less than 2.1%. TCF is about 22.3
ppm/ºC. Q value is 35000. The resonant frequency can be tuned by 20 Hz by applying 4V bias voltages.

AlN checker mode resonator

IME researchers invented an AlN piezoelectric resonators with new checker electrode architecture for two-dimensional acoustic wave excitation. The resonant frequency can be changed by adjusting the size of the electrode fingers. Hence, resonators with multiple frequencies can be fabricated on a single wafer. They are measured to provide high coupling coefficient (~4%) and suitable as building blocks for RF filters. Checker-mode resonators are good candidates for oscillator too. Improvements in resonator design to minimize anchor losses, and in device fabrication to lower residual stress, could lead to fo-Q product towards ~1012 range.

Tunable capacitor

An AlN piezoelectric actuated tunable capacitor which has advantages of low driving voltage (<5V) and large tuning range (0.2-3 pF) is currently in development.

32kHz capacitative MEMS resonator  checker mode resonator
impedence tuner checker mode resonator


IME has collaborated with five industrial partners to develop different MEMS microphones since 1996, with integrated capabilities for MEMS microphone development, including microphone & its ASIC design/simulation/optimization, 2-layer polysilicon process, microphone packaging and characterization. Directional microphone and CMOS-MEMS microphones are currently in development.


An Ultra High Sensitivity of MEMS Microphone

Pressure/ Temperature/ Infrared Sensor

By leveraging on the
AlN piezoelectric platform technology, researchers have developed a bunch of piezoelectric acoustic wave sensors, including pressure sensors, temperature sensors and IR sensors.

The core of the sensors are
AlN acoustic resonators, such as SAW and BAW resonators. Their resonant frequencies shift with temperature and pressure changes linearly. The AlN acoustic sensors have advantages of high resolution, wide range and excellent linearity up to 300 °C.

Pressure Sensor

The AlN acoustic wave pressure sensor has resolution of 0.01 psi in a range of 1-1000 psi. Pressure Coefficient Frequency (PCF) is -10 ppm/psi and Temperature Coefficient Frequency (TCF) is -40 ppm/K. It is suitable for Tyre Pressure Measure Measurement System (TPMS) and oil drilling high temperature, high pressure applications.

Temperature Sensor

The temperature sensor is a passive SAW sensor. The resonant frequency is 200-430 MHz. TCF is 32 ppm/K. It is suitable for wireless passive SAW temperature sensor system. 

Infrared (IR) Sensor

The acoustic wave IR sensor is currently developed for gas detection, humidity and temperature detector, including FIR-sensor, MIR-sensor & circuit . They have advantages of small form factor, as a result, can be made as the sensor array for imaging applications.


Pressure Sensor

Passive Temperature Sensor

Capacitive Micromachined Ultrasound Transducers (CMUT)

IME has developed CMUT array (30-50 µm per element), its related front end circuit and imaging algorithm.  Based on the requirements input from the hospital and clinicians, three ultrasound probes are being developed as below:

Ultrasound Needle Intervention

1x16 CMUT array and its front end circuit will be embedded in a biopsy needle to enable it with imaging navigation function, hence, improving the biopsy safety. It can be used for amniocentesis, epidural anesthesia and liver biopsy.

Click here to see the full diagram

Ultrasound 3D Bio-microscope (UBM)

The whole eyeball anterior segment can be divided into several regions by clinical interests. The transducer geometry distribution and signal processing strategy are adaptively optimized according to the region division.

IME filed an IP for Sparse Array configuration. The approach achieves high resolution for the most interested region by placing more transducer elements and applying biggest synthetic aperture for processing. The approach reduces the total number of transducer elements without losing information by applying adaptive threshold during logarithmic compression.

Finite Element Analysis Model

64X64 2D cMUT array for UBM

Aperture size: 12X12 mm^2

Center frequency: 50MHz

Maxim angular resolution: 50µm

Axial penetration depth:  5mm

Air-coupled Ultrasound Intraocular Pressure (IOP) Measurement System 

IME is developing air-coupled ultrasound IOP measurement system. It is non-contacted. A patient will not feel the incident ultrasonic waves. It can be potentially used for continuous monitoring.
Air-coupled Ultrasonic IOP working principle:
Elevated IOP ècorneal membrane tensional force T increases the resonant frequency and mode shape changing.
Ultrasound Doppler detection can detect vibration modes with high sensitivity.

CMOS-MEMS Integrated Sensors on Chip



CMOS-MEMS Integrated multiple-sensors on chip

  • Integrated CMOS-Compatible temperature sensor, oxygen sensor and MEMS pressure sensor.
  • MEMS pressure sensor was fabricated using post-CMOS process.
  • Three different types of sensors & sensor interface circuits fully integrated in a single CMOS chip.

Optical MEMS

Multiple developments for biomedical and consumer applications involving commercial partners.
  • 3D scanning micromirror including silicon optical bench for optical probe coherence tomography
  • Electro-magnetic micro-mirror for raster scan for projection display
  • CMOS-MEMS mega-pixel micro-mirror for projection applications
  • Slicon optical bench for submicron photonics alignment and locking 
3D Micro Mirror for OCT Probe 
Silicon optical bench for submicron photonics
alignment and locking

Inertial Sensors

IME developed the first accelerometer with a commercial partner about 15 years ago. Forming oxide filled isolation islands together with high aspect ratio DRIE were the key capabilities used. More recently, process modules for dielectric layers filled isolation trenches have also been established.
  • One axis and two axis accelerometer for automotive applications
  • Highly sensitive accelerometer development for pace maker biomedical applications
  • MEMS I consortium SOI MEMS platform with accelerometer (Specs: ± 3g, 16.6KHz, 0.19pF/g, 4x4x1 mm3) test vehicle,  includes TSV interconnects with metallic bonded cap (with a provision for CMOS –MEMS) 
  • MEMS II consortium is developing Lorentz force magnetometer (Specs: 3 axis, 2 x 2 x 0.9 mm3, ±29G, 1 mW)
single axis accelerometer (1996)

dual axis accelerometer (2000)

Single axis Accelerometer
(MEMS I consortium 2010-2012)