Ultra-Thin Chip Package (UTCP) and stretchable circuit technologies for wearable ECG system

A comfortable, wearable wireless ECG monitoring system is proposed. The device is realized using the combination of two proprietary advanced technologies for electronic packaging and interconnection : the UTCP (Ultra-Thin Chip Package) technology and the SMI (Stretchable Mould Interconnect) technology for elastic and stretchable circuits. Introduction of these technologies results in small fully functional devices, exhibiting a significant increase in user comfort compared to devices fabricated with more conventional packaging and interconnection technologies

Low power wireless sensor network for structural health monitoring of buildings using MEMS strain sensors and accelerometers

Within the MEMSCON project, a wireless sensor network was developed for structural health monitoring of buildings to assess earthquake damage. The sensor modules use custom-developed capacitive MEMS strain and 3D acceleration sensors and a low power readout application-specific integrated circuit (ASIC). A low power network architecture was implemented on top of an 802.15.4 media access control (MAC) layer in the 900MHz band. A custom patch antenna was designed in this frequency for optimal integration into the sensor modules. The strain sensor modules measure periodically or on-demand from the base station and obtain a battery lifetime of 12 years. The accelerometer modules record during an earthquake event, which is detected using a combination of the local acceleration data and remote triggering from the base station, based on the acceleration data from multiple sensors across the building. They obtain a battery lifetime of 2 years. The MEMS strain sensor and its readout ASIC were packaged in a custom package suitable for mounting onto a reinforcing bar inside the concrete and without constraining the moving parts of the MEMS strain sensor. The wireless modules, including battery and antenna, were packaged in a robust housing compatible with mounting in a building and accessible for maintenance such as battery replacement

3D Integration of ultra-thin functional devices inside standard multilayer flex laminates

Nowadays, more and more wearable electronic systems are being realized on flexible substrates. Main limiting factor for the mechanical flexibility of those wearable systems are typically the rigid components - especially the relatively large active components - mounted on top and bottom of the flex substrates. Integration of these active devices inside the flex multilayers will not only enable for a high degree of miniaturization but can also improve the total flexibility of the system. This paper now presents a technology for the 3D embedding of ultra-thin active components inside standard flex laminates. Active components are first thinned down to 20-25 mu m, and packaged as an Ultra-Thin Chip Pack-age (UTCP). These UTCP packages will serve as flexible interposer: all layers are so thin, that the whole package is even bendable. The limited total pack-age thickness of only 60 mu m makes them also suitable for lamination in between commercial flex panels, replacing for example the direct die integration. A fan-out metallization on the package facilitates easy testing before integration, solving the KGD issue, and can also relax the chip contact pitch, excluding the need for very precise placement and the use of expensive, fine-pitch flex substrates. The technology is successfully demonstrated for the 3D-integration of a Texas Instrument MSP430 low-power microcontroller, inside the conventional double sided flex laminate of a wireless ECG system. The microcontrollers are first thinned down and UTCP pack-aged These pack-ages are then laminated in between the large panels of the flex multilayer stack and finally connected to the different layers of the flex board by metallized through-hole interconnects. The thinning down, the UTCP pack-aging and the 3D-integration inside the commercial flex panels did not have any affect on the functionality of the TI microcontroller. Smaller SMD's were finally mounted on top and bottom of the integrated device

Low power wireless sensor network for building monitoring

A wireless sensor network is proposed for monitoring buildings to assess earthquake damage. The sensor nodes use custom-developed capacitive MEMS strain and 3D acceleration sensors and a low power readout ASIC for a battery life of up to 12 years. The strain sensors are mounted at the base of the building to measure the settlement and plastic hinge activation of the building after an earthquake. They measure periodically or on-demand from the base station. The accelerometers are mounted at every floor of the building to measure the seismic response of the building during an earthquake. They record during an earthquake event using a combination of the local acceleration data and remote triggering from the base station based on the acceleration data from multiple sensors across the building. A low power network architecture was implemented over an 802.15.4 MAC in the 900MHz band. A custom patch antenna was designed in this frequency band to obtain robust links in real-world conditions

In vivo validation of the electronic depth control probes.

In this article, we evaluated the electrophysiological performance of a novel, high-complexity silicon probe array. This brain-implantable probe implements a dynamically reconfigurable voltage-recording device, coordinating large numbers of electronically switchable recording sites, referred to as electronic depth control (EDC). Our results show the potential of the EDC devices to record good-quality local field potentials, and single- and multiple-unit activities in cortical regions during pharmacologically induced cortical slow wave activity in an animal model

High-yield embedding of 30µm thin chips in a flexible PCB using a photopatternable polyimide based ultra-thin chip package (UTCP)

Thinning down ICs is a well-known approach to reduce the volume of chip packages. In this work ICs are thinned down to 30um, followed by a package procedure in polyimide with copper fan out, which allows their embedding in adhesives used for laminating flexible printed circuit boards (PCBs). In this way the chip does not consume PCB area, hence other circuit components can be assembled on top or at the bottom of the chip, enabling extreme circuit miniaturization. Furthermore, our ultra-thin chip package (UTCP) is highly flexible, enabling flexible electronic circuits without large rigid chip packages. Spin-on photo-definable polyimide precursors are used to build an interposer which can be embedded later in the flexible PCB. The chip is fixed in between three polyimide layers using BCB as adhesive. The central polyimide layer forms a cavity for the chip, the top layer of polyimide is exposed and developed to fabricate vias contacting the chip. An 8um thick copper layer is deposited and patterned using lithography and etching to form the fan-out, essential to match the fine IC pitch to the larger PCB pitch. The final chip package is about 75um thick, and is easily embedded using only small adaptations of the standard flexible PCB fabrication process. Last year, both the UTCP concept and the embedding in a flexible PCB were optimized in order to obtain a very high yield. Three types of chips were UTCP-packaged and embedded in a flexible PCB: two types of microcontrollers (MSP430F1611 and a proprietary digital signal processor) and an RF-chip. The yield of the tested UTCPs ranges in between 65% (proprietary IC) and 85% (MSP430F1611). The performance of the RF-chips can only be tested after embedding in a flexible substrate. Although the testing is still ongoing, 95% of the embedded UTCPs are fully functional after embedding

Pulse Oximeter Fully Powered by Human Body Heat

The realization of a body-area network demands innovative solutions to efficiently power the wireless sensor nodes that typically consume about 100µW of power. Thermoelectric generators (TEGs) harvesting energy from wasted human body heat provide an attractive solution, potentially producing about 30µW per square centimeter of human skin. As a proof of concept, a wireless pulse oximeter has been developed that is fully powered by a watch-style TEG using commercial BiTe thermopiles. For a 15 seconds measurement interval, approximately 89µW of power is required from the generator, safely within the available 100µW power budget. The wireless pulse oximeter therefore achieves full energy autonomy. From a performance/cost perspective, superior results are expected from TEGs made up of MEMS thermopiles which are currently under development