Distal planar rotary scanner for endoscopic optical coherence tomography

Optical coherence tomography (OCT) is becoming a more common endoscopic imaging modality for detecting and treating disease given its high resolution and image quality. To use OCT for 3-dimensional imaging of small lumen, embedding an optical scanner at the distal end of an endoscopic probe for circumferential scanning the probing light is a promising way to implement high-quality imaging unachievable with the conventional method of revolving an entire probe. To this end, the present work proposes a hollow and planar micro rotary actuator for its use as an endoscopic distal scanner. A miniaturized design of this ferrofluid-assisted electromagnetic actuator is prototyped to act as a full 360° optical scanner, which is integrated at the tip of a fiber-optic probe together with a gradient-index lens for use with OCT. The scanner is revealed to achieve a notably improved dynamic performance that shows a maximum speed of 6500 rpm, representing 325% of the same reported with the preceding design, while staying below the thermal limit for safe in-vivo use. The scanner is demonstrated to perform real-time OCT using human fingers as live tissue samples for the imaging tests. The acquired images display no shadows from the electrical wires to the scanner, given its hollow architecture that allows the probing light to pass through the actuator body, as well as the quality high enough to differentiate the dermis from the epidermis while resolving individual sweat glands, proving the effectiveness of the prototyped scanner design for endoscopic OCT application.

Thermal failure analysis and control algorithm improvement for the active controlled mount with consideration of thermal-magnetic coupling

This paper proposes an improved narrowband filtered-x least mean square(FxLMS) algorithm to overcome the thermal failure problems of the active controlled mount(ACM). Firstly, the temperature-rising model and the thermal demagnetization model of the ACM are respectively developed. Combining these two models with the powertrain mounting system model, an analytical method is established for the thermal-magnetic coupling analysis of the ACM. Then a numerical simulation is carried out to obtain the permanent magnet(PM) temperature and the coil current. The ACM failure problem is discussed according to the working point trajectory. Finally, an improved algorithm is proposed. This algorithm is able to overcome the thermal failure problems by sacrificing part of the vibration isolation performance. The effectiveness of this algorithm is validated by numerical simulations and a comparison with conventional algorithms.

Development of an implantable bionic for dynamic eye closure in facial nerve paralysis: Evolution of the design

Facial nerve paralysis (FNP) presents with a constellation of clinical problems but its most concerning consequence is corneal exposure from lack of blinking. Bionic lid implant for natural closure (BLINC) is an implantable solution for dynamic eye closure in FNP. It uses an electromagnetic actuator to mobilise the dysfunctional eyelid by means of an eyelid sling. This study highlights issues relating to device biocompatibility and describes its evolution to overcome some of these issues. The essential components of the device are the actuator, the electronics including energy storage, and an induction link for wireless power transfer. Effective arrangement of these components within the anatomical confines and their integration is achieved through a series of prototypes. The response of each prototype is tested in a synthetic or cadaveric model for eye closure with the final prototype designed for acute and chronic animal trials.