Functional Fiber Junctions for Circuit Routing in E-Textiles: Deterministic Alignment of MEMS Layout With Fabric Structure

Fabrics and fibrous materials offer a soft, porous, and flexible substrate for microelectromechanical systems (MEMS) packaging in breathable, wearable formats that allow airflow. Device-on-fiber systems require developments in the field of E-Textiles including smart fibers, functional fiber intersections, textile circuit routing, and alignment methods that adapt to irregular materials. In this paper, we demonstrate a MEMS-on-fabric layout workflow that obtains fiber intersection locations from high-resolution fabric images. We implement an image processing algorithm to drive the MEMS layout software, creating an individualized MEMS “gripper” layout designed to grasp fibers on a specific fabric substrate during a wafer-to-fabric parallel transfer step. The efficiency of the algorithm in terms of a number of intersections identified on the complete image is analyzed. The specifications of the MEMS layout design such as the length of the MEMS gripper, spatial distribution, and orientation are derivable from the MATLAB routine implemented on the image. Furthermore, the alignment procedure, tolerance, and hardware setup for the alignment method of the framed sample fabric to the wafer processed using the custom gripper layout are discussed along with the challenges of the release of MEMS devices from the Si substrate to the fabric substrate.

Shorting out bonding method for multi-stack anodic bonding and its application in wafer-level packaging

Silicon/glass anodic bonding is widely investigated during MEMS packaging of multi-stack structures. The electrical behavior of anode bonding can be described as the charging and discharging process of RC circuit. Here, we conduct the equivalent RC circuit model analysis and experimental investigation, and demonstrate that voltage division and electricity leakage are the dilemma for the conventional multi-stack anodic bonding. By using feedthrough, the feasibility and convenience of “shorting out bonding” is presented, which is exampled through the wafer-level packaging of the MEMS gyroscope. Result from the sensor’s vacuum characterization reveals that shorting out bonding for multi-stack silicon/glass structures is an effective method for wafer-level packaging due to long-term stability and low temperature property.‘