Marc Boers

Room-Temperature Sealing of Microcavities by Cold Metal Welding

In this paper, we present a wafer-to-wafer attachment and sealing method for wafer-level manufacturing of microcavities using a room-temperature bonding process. The proposed attachment and sealing method is based on plastic deformation and cold welding of overlapping metal rings to create metal-to-metal bonding and sealing. We present the results from experiments using various bonding process parameters and metal sealing ring designs including their impact on the resulting bond quality. The sealing properties against liquids and vapor of different sealing ring structures have been evaluated for glass wafers that are bonded to silicon wafers. In addition, wafer-level vacuum sealing of microcavities was demonstrated when bonding a silicon wafer to another silicon wafer with the proposed room-temperature sealing and bonding technique.

Demonstration of cortical recording and reduced inflammatory response using flexible polymer neural probes

We present the fabrication, characterization, use in cortical recording and histological results of a flexible implantable neural probe. The device is microfabricated in polyimide and platinum, allowing for greater flexibility. It incorporates two layers of platinum electrodes, which greatly reduces the size of neural probes and limits the insertion damage. In recording experiments, acute in-vivo measurements were performed in the mouse cortex. Local field potential, single- and multi-neuron activity were simultaneously recorded. We demonstrate using immunohistochemistry techniques reduced inflammation at the implantation site for microfabricated polyimide neural probes. We therefore show that the major advantage of using polymer probes over silicon probes is the reduced damage due to insertion and probe-brain compliance mismatch.

Novel room-temperature wafer-to-wafer attachment and sealing of cavities using cold metal welding

In this paper we present for the first time a wafer-to-wafer attachment and sealing method for wafer level manufacturing of micro-cavities using a room temperature bonding process. The proposed attachment and sealing method is based on plastic deformation and cold welding of overlapping metal rings to create metal-to-metal bonding and sealing. We present the results from experiments using various bonding process parameters and metal sealing ring designs and their impact on the resulting bonds. Experiments are performed to evaluate the sealing properties against liquids and vapors of the different sealing ring structures.

Millinewton force sensor based on low temperature co-fired ceramic (LTCC) technology

Fabrication of a millinewton force sensor, which is based on LTCC technology as an alternative to the widely used alumina (Al2O3) is described. The new sensor, integrated with piezoresistor thick-film, has shown an increase in the sensitivity by two times compared to the alumina-based version in the first attempt. This is ascribed to the smaller elastic modulus and finer substrate thickness attainable by LTCC. Moreover design flexibility is also an important factor, which contributes to the increased sensitivity of the sensor. It is strongly expected that the device performance can further be improved, by modifying the co-fired LTCC components such as LTCC tape and the thick-film terminations.

Structuration and Fabrication of Sensors Based on LTCC (Low Temperature Co-Fired Ceramic) Technology

The purpose of this paper is to demonstrate sensors and structures fabricated using the LTCC technology, which has been addressed and employed increasingly as a smart packaging approach for several applications. The focus will be on inclination and cantilever force sensors and micro-fluidic structures. Motivation for selection of LTCC for these applications in addition to fabrication and structuring of the devices will be explained in details. TGA (thermo-gravimetric analysis), dilatometer analysis, SEM (scanning electron microscopy), electronic equipment for measuring sensor performance will be extensively used for explanation of the results. It will also be shown that, compared to classical thick-film technology on alumina, LTCC allows a considerable increase in sensitivity, and is therefore better suited for the sensing of minute forces and pressures.