Bjorn Vandecasteele

ENOBIO - FIRST TESTS OF A DRY ELECTROPHYSIOLOGY ELECTRODE USING CARBON NANOTUBES

We describe the development and first tests of ENOBIO, a dry electrode sensor concept for biopotential applications. In the proposed electrodes the tip of the electrode is covered with a forest of multi-walled carbon nanotubes (CNTs) that can be coated with Ag/AgCl to provide ionic-electronic transduction. The CNT brush-like structure is to penetrate the outer layers of the skin improving electrical contact as well as increase the contact surface area. In this paper we report the results of the first tests of this concept-immersion on saline solution and pig skin signal detection. These indicate performance on a par with state of the art research-oriented wet electrodes

A chip embedding solution based on low-cost plastic materials as enabling technology for smart labels

Expanding the current smart packaging solutions to individual products requires improvement for several of the following properties: cost, thickness, weight, flexibility, conformability, transparency, and even stretchability. This paper focusses on an embedding technology that targets the first four properties, with an emphasis on cost reduction. The progress on the development work for this foil-based embedding is reported, along with a detailed failure analysis of the process flow. A functional demonstrator is realized in the form of a smart sensing label, including an embedded micro controller. Practical and technological shortcomings of the current technology are used as a starting point for proposing an improved embedding technology based on low-cost plastic materials. The first developments for lamination and via interconnection are described.

An approach to produce a stack of photo definable polyimide based flat UTCPs

Getting output of multiple chips within the volume of a single chip is the driving force behind development of this novel 3D integration technology which has a broad range of industrial and medical electronic applications. This can be achieved by laminating multiple layers of spin-on polyimide based ultrathin chip packages (UTCPs) with fine pitch through hole interconnects.

Interconnecting drivers to flexible displays

Several options to interconnect driver chips to a flexible display are discussed and investigated. In the first option, bare test dies are flip-chip (FC) assembled onto polyethylene terephthalate ( PET) display substrates. The second option involves test flexible polyimide ( PI) substrates, imitating tape-carrier-packaged drivers (TCP), bonded onto the same PET substrates, whereas the third option uses actual TCPs on stainless-steel display substrates. Each option makes use of bonding technology with anisotropically conductive adhesive, supplied as film (ACF). The reason for using ACF is that drivers typically have high output counts, and therefore very fine pad features, 200-mu m pitch and below. The technology has been adapted for each option, considering the requirements of the substrate. Every option includes an explanation of the bond test setup, the bonding process itself, and a discussion of the test results. The conclusion summarizes the achievements made in the research reported in this article.

Sn whisker evaluations in 3D microbumped structures

Abstract Sn whiskering remains a reliability concern in electronic applications. Despite extensive research on growth rates and mitigation strategies, no predictive theory is in place. Literature data are available for Cu/Sn-based films and coatings as well as for board-level and flip-chip solder bumps but data are scarce for scaled-down solder volumes and for higher intermetallic-to-solder ratios. The current work investigates whiskers in “isolated geometries” for 3D solder-capped Cu microbumps with >2 orders of magnitude smaller solder volumes compared to state-of-the-art. To the best of the authors’ knowledge, this is the first time Sn whisker growth is reported in isolated solder volumes (e.g.

Miniaturized pumps and valves, based on conductive polimer actuators, for lab-on-chip application

We developed a new type of conductive polymer (CP) actuator, specifically designed for miniaturized pumps and valves for lab-on-a-chip (LoC) applications. CP films soaked in an electrolyte solution reversibly change their thickness upon bias application. A large stroke actuator was fabricated by stacking several CP layers, bonded together by means of epoxy dots. The CP deposition process was optimized for obtaining the low surface roughness required for stacking. The maximum strain of stacked actuators and of individual layers was identical (13%), indicating that the dot gluing process eliminates strain losses previously observed in multi-layers actuators. Pumps and valves were fabricated and mounted on a microfluidic chip.

Integration of thick film resistors in a multilayer structure

Today, demands for electronic components are getting higher, with requirements containing smaller size, better reliability, higher integration and cheaper production. This paper presents some results of the work on voltage-controlled oscillators (VCO), especially on the problem of integration of resistors. The benefits coming from using thick film materials are low cost production, reliability and rigidity. The paper describes the behavior of thick film cermet resistors integrated in a multilayer structure based on Fodel dielectric material. Trimming in such multilayer structures is not always possible. Our goal was to asses this behavior with regard to resistor design and their resulting value. The effect of the refiring process and the interaction between resistor material and dielectrics was investigated.