Optical fiber Fabry-Pérot micro-displacement sensor for MEMS in-plane motion stage.

Fabry-Pérot interferometer sensors have been widely used in Micro-Electro-Mechanical-Systems (MEMS) due to high displacement accuracy and immunity to electromagnetic noises, but they are still limited by micro scale measurement range. In this paper, a Fabry-Pérot interferometer in-plane displacement sensor is proposed for measuring the displacement of MEMS devices utilizing a polished optical fiber and a modulated laser source. The polished optical fiber and a sidewall of a MEMS device form an optical cavity for the proposed sensor. The sinusoidal phase modulation with extreme point search algorithm enables the proposed sensor to measure displacements larger than the wavelengths of the laser light in real time. The experimental results show that the proposed displacement sensor has a capability to measure displacements larger than 3 µm and it shows the measurement accuracy less than 35 nm. The proposed displacement sensor is then embedded on a single degree-of-freedom MEMS motion stage and tested to monitor its displacement in real time.

Metrology and Standards Needs for Some Categories of Medical Devices.

With rapid advances in meso-, micro- and nano-scale technology devices and electronics, a new generation of advanced medical devices is emerging, which promises medical treatment that is less invasive and more accurate, automated, and effective. We examined the technological and economic status of five categories of medical devices. A set of metrology needs is identified for each of these categories and suggestions are made to address them.

Capacitive displacement sensor for detecting planar submicrometer motion.

This paper describes the design of a very simple displacement sensor that measures the change in the position of an object by sensing the change in capacitance due to the movement of this object in the sensor fringing electric field. Two sensor geometries with small footprints were considered and several sensor variations were built and tested. At distances of approximately 0.5 µm and 30 µm, test results demonstrated that the sensors' resolution was in the order of tens of nanometers.

Human-Robot Collaboration Dynamic Impact Testing and Calibration Instrument for Disposable Robot Safety Artifacts.

The Dynamic Impact Testing and Calibration Instrument (DITCI) is a simple instrument with a significant data collection and analysis capability that is used for the testing and calibration of biosimulant human tissue artifacts. These artifacts may be used to measure the severity of injuries caused in the case of a robot impact with a human. In this paper we describe the DITCI adjustable impact and flexible foundation mechanism, which allows the selection of a variety of impact force levels and foundation stiffness. The instrument can accommodate arrays of a variety of sensors and impact tools, simulating both real manufacturing tools and the testing requirements of standards setting organizations. A computer data acquisition system may collect a variety of impact motion, force, and torque data, which are used to develop a variety of mathematical model representations of the artifacts. Finally, we describe the fabrication and testing of human abdomen soft tissue artifacts, used to display the magnitude of impact tissue deformation. Impact tests were performed at various maximum impact force and average pressure levels.

Design of a 1 DOF MEMS motion stage for a parallel plane geometry rheometer.

Rotational rheometers are used to measure paste properties, but the test would take too long to be useful for quality control (QC) on the job site. In this paper, a new type of rheometer is proposed based on a one degree of freedom (DOF) micro-electro-mechanical systems (MEMS)-based motion stage. Preliminary data will be presented to show the capability of the system to measure the viscoelastic properties of a paste. The parallel plate geometry rheometer consists of two plates, which move relative to each other to apply a strain to the material to be tested. From the stress measured and the strain applied, the rheological characteristics of the material can be calculated. The new device consists of an electrothermal actuator and a motion plate. For the rheological measurements, the device is designed to generate the shear stress up to 60 Pa and maintain its stiffness to less than 44 N/m. With these features, the device uses a square plate of 1.5 mm x 1.5 mm to provide enough area for a few micro-liter level volumes. The motion of the square plate is monitored by a capacitive sensor at the end of the oscillating plate which has a resolution of 1.06 µm. When a reference cementitious paste, Standard Reference Material (SRM)-2492, is placed between the oscillating plate of the presented motion stage and a fixed plate, the reduction in the displacement of the oscillating plate is monitored showing that the presented motion stage is reasonably designed to detect the response of the reference cementitious paste.