Koji Uemura

Fabrication of Si Field Emitter Tip for a Three-Dimensional Vacuum Magnetic Sensor

A new Si field emitter tip generating a cross-shaped electron beam was fabricated for a three-dimensional vacuum magnetic sensor (VMS) application. The present tip is surrounded by a gate for field emission, and a focusing lens is made in the same plane as the gate. The beam current of about 50 nA was obtained with a single tip at the gate and lens voltages of 55 V and 10 V, respectively. The fabrication process and beam characteristics are described. Preliminary results such as linearity and sensitivity of VMS using the present tip are also discussed.

Three-dimensional vacuum magnetic sensor with a Si emitter tip

A vacuum magnetic sensor (VMS) using a silicon field emitter tip was fabricated and demonstrated. The VMS is constructed with the emitter tip generating a cross-shaped electron beam, an anode divided into eight symmetrical sectors and a vacuum-sealed glass package. The Si tip is centered in a cross-shaped extraction gate surrounded by four in-plane focusing lenses and emits a cross-shaped electron beam of 0.5 μA in current at the gate voltage of 60 V. The magnetic field externally applied to the VMS causes the translational and rotational displacement of the cross-shaped beam at the anode and these displacements are measured by detecting the difference in anode currents between neighboring two anode sectors. From preliminary experiments, we found that the present VMS had the sensitivity higher than 104(%/T).

Fabrication of a Three-Dimensional Vacuum Magnetic Sensor with a Si Tip

A new vacuum magnetic sensor (VMS) device suitable for three-dimensional detection of magnetic flux was fabricated. This device consists of a Si field emitter tip that generates a cross-shaped electron beam and an anode that is divided into eight symmetrically arranged sectors. The cross-shaped electron beam is rotated and displaced from an initial position by the magnetic flux in accordance with the Lorentz force interaction. The rotation angle and the translational displacement were measured from the beam current imbalance between two neighboring anode sectors. Detection sensitivities of 10 4 %/T and 10 3 %/T were obtained for magnetic flux applied parallel and perpendicular to the VMS device, respectively.

Two axial shearing force measurement device with a micro displacement sensor

We propose a promising biaxial shearing force measurement device with an integrated micro displacement sensor (chip size of 3 mm by 3 mm and 0.7 mm in thickness) housed in an external trapezoidal metallic frame. Applying shearing force on the surface of the frame, the tilts occur on the ceiling of the frame. We can measure that tilts as a shearing force by micro displacement sensor and we obtained a linear signal response to applied biaxial shearing force. The range and sensitivity of the sensor depends on the material or thickness of the frame, therefore we can apply the sensor to various possible applications by changing its shape.