A review was presented to demonstrate a historical description of the synthesis of light-emitting conjugated polymers for applications in electroluminescent devices. Electroluminescence (EL) was first reported in poly(para-phenylene vinylene) (PPV) in 1990 and researchers continued to make significant efforts to develop conjugated materials as the active units in light-emitting devices (LED) to be used in display applications. Conjugated oligomers were used as luminescent materials and as models for conjugated polymers in the review. Oligomers were used to demonstrate a structure and property relationship to determine a key polymer property or to demonstrate a technique that was to be applied to polymers. The review focused on demonstrating the way polymer structures were made and the way their properties were controlled by intelligent and rational and synthetic design.

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

Human skin is a remarkable organ. It consists of an integrated, stretchable network of sensors that relay information about tactile and thermal stimuli to the brain, allowing us to maneuver within our environment safely and effectively. Interest in large-area networks of electronic devices inspired by human skin is motivated by the promise of creating autonomous intelligent robots and biomimetic prosthetics, among other applications. The development of electronic networks comprised of flexible, stretchable, and robust devices that are compatible with large-area implementation and integrated with multiple functionalities is a testament to the progress in developing an electronic skin (e-skin) akin to human skin. E-skins are already capable of providing augmented performance over their organic counterpart, both in superior spatial resolution and thermal sensitivity. They could be further improved through the incorporation of additional functionalities (e.g., chemical and biological sensing) and desired properties (e.g., biodegradability and self-powering). Continued rapid progress in this area is promising for the development of a fully integrated e-skin in the near future.

25th Anniversary Article: The Evolution of Electronic Skin (E-Skin): A Brief History, Design Considerations, and Recent Progress

Current medical imaging technologies allow visualization of tissue anatomy in the human body at resolutions ranging from 100 micrometers to 1 millimeter. These technologies are generally not sensitive enough to detect early-stage tissue abnormalities associated with diseases such as cancer and atherosclerosis, which require micrometer-scale resolution. Here, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter. This method, referred to as "optical biopsy," was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.

In Vivo Endoscopic Optical Biopsy with Optical Coherence Tomography

A method embodiment includes forming a sacrificial film layer over a top surface of a die, the die having a contact pad at the top surface. The die is attached to a carrier, and a molding compound is formed over the die and the sacrificial film layer. The molding compound extends along sidewalls of the die. The sacrificial film layer is exposed. The contact pad is exposed by removing at least a portion of the sacrificial film layer. A first polymer layer is formed over the die, and a redistribution layer (RDL) is formed over the die and electrically connects to the contact pad.

Fan-out interconnect structure and method for forming same

In this paper, we report a new flexible capacitive tactile sensor array with the capability of measuring both normal and shear force distribution using polydimethylsiloxane (PDMS) as a base material. A tactile cell consists of two thick PDMS layers with embedded electrodes, an air gap, and a pillar structure. The pillar structure is formed at the center of each tactile cell between the air gap under a large bump. There are four capacitors in a cell to decompose the contact force into normal and shear components. Four capacitors are arranged in a square form. If a normal force is applied on the bump, the PDMS layer on the pillar structure is compressed, and the air gap between the top and bottom electrodes decreases, resulting in the increase in all four capacitances. If a shear force is applied, a torque is induced around the pillar. Therefore, the capacitance of the two capacitors increases, whereas that of the other two decreases. The bump and the pillar structure play a critical role to generate a torque for shear force measurement. The sensor has been realized in an 8 x 8 array of unit sensors, and each unit sensor responds to normal and shear stresses in all three axes, respectively. Measurement of a single sensor shows that the full-scale range of detectable force is about 10 mN, which corresponds to 131 kPa in three directions. The sensitivities of a cell measured with a current setup are 2.5%/mN, 3.0%/mN, and 2.9 %/mN for the x-, y-, and z-directions, respectively. Normal and shear force images are also captured from a 4 x 4 array of the fabricated sensor. Distinctive characteristic patterns appear when a shear force is applied to the sensor.

Normal and Shear Force Measurement Using a Flexible Polymer Tactile Sensor With Embedded Multiple Capacitors

A device that is hermetically sealed at a wafer level or a method of hermetically sealing a device, which is sensitive to high temperatures or affected by heating cycles. Semiconductor devices are formed on a wafer. A lid wafer is formed. Adhesives are formed in a predetermined position over the wafer and/or the lid wafer. The wafer and the lid wafer are sealed by the adhesives at the wafer level. The sealing may be performed at a low temperature using a solder to protect the devices sensitive to heat. The sealed devices are diced into individual chips. In the wafer level hermetic sealing method, a sawing operation is performed after the devices are sealed. Therefore, the overall processing time is reduced, devices are protected from the effects of moisture or particles, and devices having a moving structure, such as MEMS devices, are more easily handled.

Wafer level hermetic sealing method

A hermetic sealing method, which is capable of preventing oxidation of a micro-electromechanical system (MEMS) and sealing the MEMS at a low temperature. A low temperature hermetic sealing method having a passivation layer includes depositing a junction layer, a wetting layer, and a solder layer on a prepared lid frame, depositing a first protection layer for preventing oxidation on the solder layer and forming a lid, preparing a package base on which a device is disposed, and in which a metal layer and a second protection layer are formed around the device, and assembling the lid and the package base, heating, and sealing them. The protection layer is laminated on the solder layer that is formed by the lid, thereby preventing oxidation without using a flux. The low temperature hermetic sealing method having a passivation layer is suitable for sealing a device, such as the MEMS, which is sensitive to heat, water and other by-products.

Low temperature hermetic sealing method having passivation layer

Development of packaging is one of the critical issues toward realizing commercialization of radio-frequency-microelectromechanical system (RF-MEMS) devices. The RF-MEMS package should be designed to have small size, hermetic protection, good RF performance, and high reliability. In addition, packaging should be conducted at sufficiently low temperature. In this paper, a low-temperature hermetic wafer level packaging scheme for the RF-MEMS devices is presented. For hermetic sealing, Au-Sn eutectic bonding technology at temperatures below 300°C is used. Au-Sn multilayer metallization with a square loop of 70 µm in width is performed. The electrical feed-through is achieved by the vertical through-hole via filling with electroplated Cu. The size of the MEMS package is 1 mm × 1 mm × 700 µm. The shear strength and hermeticity of the package satisfies the requirements of MIL-STD-883F. Any organic gases or contamination are not observed inside the package. The total insertion loss for the packaging is 0.075 dB at 2 GHz. Furthermore, the robustness of the package is demonstrated by observing no performance degradation and physical damage of the package after several reliability tests.

Application of Au-Sn eutectic bonding in hermetic radio-frequency microelectromechanical system wafer level packaging

An image sensor module having a sensor chip closely adhered on a concave surface and a fabrication method thereof are disclosed. The image sensor module includes at least one sensor chip, at least one sensor chip-mounting structure comprising a substrate and a polymer layer formed on the substrate, the polymer layer having an concave surface formed on an upper part thereof by a polymer molding method, so that the sensor chip is bent and bonded on the concave surface, and at least one lens fixed on the at least one sensor chip-mounting structure above the sensor chip.

Image sensor module and fabrication method thereof

A flexible image photographing apparatus includes a plurality of image photographing units to photograph a photographing object. A flexible body receives the plurality of image photographing units and may be transformed when a force is applied. A control portion is disposed at the flexible body to control each of the plurality of image photographing units to photograph the photographing object. The control portion stores images of the photographing object and performs various kinds of photography.

Woon-bae Kim

Papers

Wafer level hermetic sealing method

Low temperature hermetic sealing method having passivation layer

Application of Au-Sn eutectic bonding in hermetic radio-frequency microelectromechanical system wafer level packaging

Image sensor module and fabrication method thereof

Flexible image photographing apparatus with a plurality of image forming units and method for manufacturing the same