Meng-Shiue Lee

Electromagnetic/Magnetic-Coupled Targeting System for Screw-Hole Locating in Intramedullary Interlocking-Nail Surgery

At present, intramedullary interlocking nails are widely used for bone-fracture fixation in orthopedic surgeries. Surgeons often use X-ray imaging to find the actual location of the distal screw-holes of the nail after the nail is inserted into the medullary canal of a bone for fixation. Thus, the patients and medical team are inevitably exposed to radioactivity. In this paper, we report a radiation-free electromagnetic/magnetic-coupled targeting system to locate the distal screw-holes of the nail used in interlocking-nail surgery. The targeting system consists of a c-shaped electromagnet with a pick-up coil, a highly permeable curved silicon-steel strip embedded on the nail, a guiding mechanism, and electronic measuring instruments. An alternative current is applied to the electromagnet to generate a uniform magnetic field/flux in the electromagnets air gap. When the nail inserted into the medullary canal of a bone is scanned through or rotated in the air gap of the electromagnet, the magnetic flux in the air gap is influenced by the silicon-steel strip embedded on the nail. The variation of the magnetic flux induces a voltage response in the pick-up coil due to electromagnetic induction. The pattern of the voltage response is analyzed to establish a criterion for screw-hole targeting. The results obtained using this criterion reveal that the maximum targeting error of the location and orientation targeting for a screw-hole with a diameter of 5 mm is <;2 mm and 10°, respectively. Thus, the system/approach is sufficiently simple and accurate to be used by surgeons in clinical surgery.

An electromagnetic-induction approach for screw-hole targeting in interlocking-nail surgery

We report a novel approach for targeting screw-holes of an intramedullary nail in a long-bone fracture surgery. The approach utilizes the electromagnetic induction to avoid over exposure of radioactivity which is the critical issue in conventional X-ray-imaging targeting method. Based on the approach, we fabricate a targeting system. The targeting system consists of a c-shaped electromagnet, detecting-coil, guiding-mechanism, and measurement electronics. When a voltage is applied to the electromagnet, magnetic flux is generated in the air gap of the electromagnet and subsequently detected by the coil. When the flux is detected by the coil, a voltage response is induced in the coil. When a nail in a bone is scanned through the air gap of the electromagnet, the flux is influenced due to a discrepancy of the permeability between the location with and without the hole of the nail. The influenced flux induces different voltage response in the coil. Through analyzing the voltage response, we establish a criterion for targeting the holes. By the criterion, the experimental result shows the maximum error of targeting a hole with a diameter of 5 mm is less than 2.5 mm.

A novel guiding device for distal locking of intramedullary nails

This paper presents the prototype of a new remote guiding device to find the accurate screw hole position for drilling and direction for locking in intramedullary nailing surgery. The device consists of three magnetic pins and an electrical conductive board. The three symmetrically placed magnetic pins can rotate freely and point to the permanent magnet inside the nail. The drilling position and screwing direction can be obtained by moving the device with those magnetic pins to align with the magnet in the nail. The alignment condition is indicated by a LED. When the device is not aligned with the magnet in the nail properly, either in position or direction, the pins then will contact with the board to trigger a light-emitting diode for alarming.

A Resettable, Wireless and Passive Fall-Down Recorder Using a Magnetic Droplet With an

A fall-down recorder can record the happening of an object falling down during object delivery or transportation, even after the object is recovered to its initial state. Here, a resettable, wireless and passive fall-down recorder is proposed by integrating a droplet-based inertial force switch with the inductor-capacitor (LC) circuit for wireless signal transmission. A magnetic droplet is used in the switch with a converging microchannel to control the desired threshold acceleration. When the inertial force exceeds the designed threshold acceleration, the magnetic droplet will pass through the converging microchannel to a deep cavity to become a different state. By connecting the switch with the sensing LC circuit, the state of the recorder can be wirelessly identified through the LC resonant frequency. After triggering, this switch can be remotely reset to its initial state by an external magnet. A proper hydrophobic surface treatment is employed to facilitate the movement of the magnetic droplet and reduce the variation on the threshold acceleration. The capabilities, including switching, recording, wireless reading, and resetting of the proposed fall-down recorder, are successfully designed, fabricated, and verified with ten recording-reset tests.

LC

One of the challenges in IVF treatment is to improve the pregnancy rate of selective single embryo implantation. The concentration of IL-1β in embryo culture medium may help to predict pregnancy rate. Clinically, each embryo can only get small amount of sample size. However, the traditional immunoassay cannot detect biomarkers in such small sample sizes. Therefore, we combined immunoassay with the bead-based digital microfluidic chip. The chip has two advantages, low sample requirement and low detection limit. We established the mouse IL-1β calibration curve, confirm the Human Tubal Fluid (HTF) does not influence the test result and demonstrate that mouse IL-1β in clinical mouse embryo culture medium is positively correlate to cultured days. This device has a great potential for increasing IVF pregnancy rates.

Circuit

Interlocking nailing is a common surgical operation to stabilize fractures in long bones. One of the difficult parts of the surgery is how to locate the position and direction of a screw hole on the interlocking nail, which is invisible to the naked eye after insertion of the nail into the medullary canal. Here, we propose a novel two-stage targeting process using two passive magnetic devices to locate the position and direction of the screw hole without radiation for the locking screw procedure. This involves a ring-shape positioning magnet inside the nail to generate a magnetic field for targeting. From the accuracy test results of these two-stage targeting devices, the search region can be identified in less than 20 seconds by the 1st-stage targeting device, while the total targeting time to locate the drilling position and direction takes less than 4 minutes, with 100% successful rate in 50 attempts. The drilling test further combines the two-stage targeting process and drilling process on the swine tibia, and it is shown that a 100% successful rate is achieved in all 10 attempts, where the total time needed is less than 5 minutes.

Bead-based digital microfluidic immunoassay for IL-1β detection in embryo culture medium

An implantable system for drug delivery provides a new strategy for drug therapy, and typically involves a microfluidic chip produced with micro or nano-technology. Implantable systems have the flexibility to conform various schemes of drug release, including zero order, pulsatile, and on demand dosing, as opposed to a standard sustained release profile. Such an implantable system is classified as allowing either controllable or uncontrollable drug release after implantation, so an active or passive delivery system respectively. The performance and related applications of these systems vary. The key points of each technology are highlighted such as performance, working principle, fabrication methods, and dimensional constrains. We here review the implantable drug-delivery system in current research with a focus on application and chip performance, and comparison for passive and active delivery system.