The importance of understanding the mechanical behavior of tissues is starting to be recognized in medical diagnostics. It is becoming clear that pathological tissues behave mechanically differently than do healthy tissues. However, traditional optical evaluation methods, particularly speckle-based methods, have not proven to be effective in assessing the mechanics of biological soft tissues. T...

A multi-longitudinal-mode fiber ring laser sensor is firstly proposed and experimentally demonstrated. Beat frequencies between any two longitudinal modes are used as sensing signal. The core component of the system is a multi-longitudinal-mode fiber ring cavity laser sensor based on beat frequency demodulation method. The theory of beat signal generation and strain measurement are discussed in...

This research investigates a passive wireless antenna sensor designed for strain and crack sensing. When the antenna experiences deformation, antenna shape changes, causing shift in electromagnetic resonance frequency of the antenna. A radio frequency identification (RFID) chip is adopted for antenna signal modulation, so that a wireless reader can easily distinguish backscattered sensor signal...

Planetary gearboxes are widely used in the drivetrain of helicopters and wind turbines. Any planetary gearbox failure could lead to breakdown of the whole drivetrain and major loss of helicopters and wind turbines. Therefore, planetary gearbox fault diagnosis is an important topic in prognostics and health management (PHM). Planetary gearbox fault diagnosis has been done mostly through vibratio...

In high speed and high precision machining applications, it is important to monitor the machining process in order to ensure high product quality. For this purpose, it is essential to develop a dynamometer with high sensitivity and high natural frequency which is suited to these conditions. This paper describes the design, calibration and performance of a milling torque sensor based on piezores...

This work develops optimal sensor placement within a hybrid dense sensor network used in the construction of accurate strain maps for large-scale structural components. Realization of accurate strain maps is imperative for improved strain-based fault diagnosis and prognosis health management in large-scale structures. Here, an objective function specifically formulated to reduce type I and II e...

Polyvinylidene Flouride (PVDF) is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental "stress-averaging" mechanis...

This research studies the wireless strain sensing performance of a slotted patch antenna sensor. In our previous work, a folded patch antenna was designed for passive wireless strain and crack sensing. When experiencing deformation, the antenna shape changes, causing shift in electromagnetic resonance frequency of the antenna. The wireless interrogation system utilizes the principle of electrom...

In this work, a fiber Bragg grating (FBG) sensing system which can measure the transient response of out-of-plane point-wise displacement responses is set up on a smart cantilever beam and the feasibility of its use as a feedback sensor in an active structural control system is studied experimentally. An FBG filter is employed in the proposed fiber sensing system to dynamically demodulate the r...

Since the discovery of carbon nanotubes by Iijima in 1991, researchers have utilized carbon nanotubes for a wide array of applications including nanoelectronics, sensors, and inductively coupled antennas. While current and novel strain transducers can measure strain adequately, their large form factor and cabled data acquisition systems render their use in harsh environments difficult. It has b...