Antti Rautiainen

Diamond-like carbon (DLC) thin film bioelectrodes: effect of thermal post-treatments and the use of Ti adhesion layer.

The effect of thermal post-treatments and the use of Ti adhesion layer on the performance of thin film diamond like carbon bioelectrodes (DLC) have been investigated in this work. The following results were obtained: (i) The microstructure of the DLC layer after the deposition was amorphous and thermal annealing had no marked effect on the structure, (ii) formation of oxygen containing SiOx and Ti[O,C] layers were detected at the Si/Ti and Ti/DLC interfaces with the help of transmission electron microscope (TEM), (iii) thermal post-treatments increased the polar fraction of the surface energy, (iv) cyclic voltammetry (CV) measurements showed that the DLC films had wide water windows and were stable in contact with dilute sulphuric acid and phosphate buffered saline (PBS) solutions, (v) use of Ti interlayer between Pt(Ir) microwire and DLC layer was crucial for the electrodes to survive the electrochemical measurements without the loss of adhesion of the DLC layer, (vi) DLC electrodes with small exposed Pt areas were an order of magnitude more sensitive towards dopamine than Pt electrodes and (vii) thermal post-treatments did not markedly change the electrochemical behavior of the electrodes despite the significant increase in the polar nature of the surfaces. It can be concluded that thin DLC bioelectrodes are stable under physiological conditions and can detect dopamine in micro molar range, but their sensitivity must be further improved.

Migration From PLC to IEC 61499 Using Semantic Web Technologies

This paper proposes a new methodology of migration from IEC 61131-3 PLCs to IEC 61499 function blocks. The aim of this migration process is to recreate IEC 61131-3 applications in IEC 61499 implementations with equivalent execution behavior. The formal model of the IEC 61131-3 standard for migration and cyclical execution model is defined. This method also creates a foundation for correct-by-design development tools and automatic migration between the IEC 61131-3 and IEC 61499 standard. Formal migration rules based on ontology mappings, restoring execution model including tasks and programs scheduling and variables mapping with different access levels, are provided. A transformation engine for importing PLC code, mapping from PLC ontology model to function block model and code generation is implemented based on the ontological knowledge base and semantic query-enhanced web rule language. The migration approach is demonstrated on a simple airport baggage handling system.This paper proposes a new methodology of migration from IEC 61131-3 PLCs to IEC 61499 function blocks. The aim of this migration process is to recreate IEC 61131-3 applications in IEC 61499 implementations with equivalent execution behavior. The formal model of the IEC 61131-3 standard for migration and cyclical execution model is defined. This method also creates a foundation for correct-by-design development tools and automatic migration between the IEC 61131-3 and IEC 61499 standard. Formal migration rules based on ontology mappings, restoring execution model including tasks and programs scheduling and variables mapping with different access levels, are provided. A transformation engine for importing PLC code, mapping from PLC ontology model to function block model and code generation is implemented based on the ontological knowledge base and semantic query-enhanced web rule language. The migration approach is demonstrated on a simple airport baggage handling system.

Improving the function of dopamine electrodes with novel carbon materials

For therapeutic purposes, an accurate measurement of dopamine level in situ would be highly desirable. A novel strategy for the selective determination of dopamine concentration based on the diamond-like carbon (DLC) electrode is presented in this abstract. The developed DLC electrode is able to detect 10 μM dopamine and has improved sensitivity compared to platinum. Compared to carbon fiber electrodes, the DLC electrode is more stable because the background current is much lower.

Reliability Performance of Au-Sn and Cu-Sn Wafer Level SLID Bonds for MEMS

Wafer level Solid-Liquid Interdiffusion (SLID) bonding is used to encapsulate MEMS devices. The metals in SLID bonds can improve the reliability by absorbing mechanical and thermo-mechanical stresses. In this paper, the reliability of wafer level Au-Sn-(Ni) and Cu-Sn SLID bonds was systematically characterized and evaluated with shear/tensile tests, shear fatigue test, mixed flow gas (MFG) test, high temperature storage (HTS) test and thermal shock (TS) test. The failure modes and physical mechanisms were analyzed. Overall, the results demonstrated the high mechanical strength and reliability of SLID bonds. Utilizing the reliability results the design of seal bonds for MEMS encapsulation could be improved.

Wafer-Level AuSn/Pt Solid–Liquid Interdiffusion Bonding

In this paper, wafer-level AuSn/Pt solid–liquid interdiffusion bonding for hermetic encapsulation of microelectromechanical systems (MEMS) is evaluated. Although AuSn is used for bonding of ICs, the implementation of AuSn diffusion bonding in MEMS applications requires thorough understanding of its compatibility with the complete layer stack including adhesion, buffer, and metallization layers. Partitioning of the layer stacks is possible in MEMS devices consisting of several silicon wafers since the device wafer carrying functional structures and the encapsulation wafer have different restrictions on process integration and applicable metal deposition techniques. In this paper, CMOS/MEMS compatible sputtered platinum is utilized on the device wafer as a contact metallization for Au–Sn metallized cap wafer. The role of the platinum layer thickness as well as the nickel and molybdenum buffer layers on mechanical reliability were tested. The mechanical shear and tensile tests were performed for samples after bonding as well as after high-temperature storage and thermal shock tests. The results were rationalized based on the combined microstructural, thermodynamic, and fracture surface analyses. High-strength and thermodynamically stable bonds were achieved, exhibiting shear strength up to ~180 MPa and tensile strength up to ~80 MPa. Platinum was consumed completely during bonding and was observed to dissolve mainly into the (Au,Pt)Sn phase. Thicker platinum layer (200 versus 100 nm) increased the (Au,Pt)Sn phase thickness and resulted in higher strength. The molybdenum buffer layer under the platinum metallization increased the tensile strength significantly.