Kari Kautio

Toward an Injectable Continuous Osmotic Glucose Sensor

Background: The growing pandemic of diabetes mellitus places a stringent social and economic burden on the society. A tight glycemic control circumvents the detrimental effects, but the prerogative is the development of new more effective tools capable of longterm tracking of blood glucose (BG) in vivo. Such discontinuous sensor technologies will benefit from an unprecedented marked potential as well as reducing the current life expectancy gap of eight years as part of a therapeutic regime. Method: A sensor technology based on osmotic pressure incorporates a reversible competitive affinity assay performing glucose-specific recognition. An absolute change in particles generates a pressure that is proportional to the glucose concentration. An integrated pressure transducer and components developed from the silicon micro- and nanofabrication industry translate this pressure into BG data. Results: An in vitro model based on a 3.6 × 8.7 mm large pill-shaped implant is equipped with a nanoporous membrane holding 4–6 nm large pores. The affinity assay offers a dynamic range of 36–720 mg/dl with a resolution of ±16 mg/dl. An integrated 1 × 1 mm2 large control chip samples the sensor signals for data processing and transmission back to the reader at a total power consumption of 76 μW. Conclusions: Current studies have demonstrated the design, layout, and performance of a prototype osmotic sensor in vitro using an affinity assay solution for up to four weeks. The small physical size conforms to an injectable device, forming the basis of a conceptual monitor that offers a tight glycemic control of BG.

Fiber-Optic Transceiver Module for High-Speed Intrasatellite Networks

High-speed intrasatellite networks are needed to interconnect units such as synthetic aperture radars, high-resolution cameras, and fast image-compression processors that produce data beyond gigabits per second. We have developed a fiber-optic link, named SpaceFibre, which operates up to 3.125 Gb/s and is compatible with the existing SpaceWire network. The link provides symmetrical, bidirectional, full-duplex, and point-to-point communication. It employs 850-nm vertical-cavity surface emitting lasers, radiation-hardened laser-optimized 50/125 mum graded-index fibers, and GaAs p-i-n photo diodes. The transceiver electronics is realized using a multilayer-ceramic-substrate technology that enables the passive alignment of optical fibers to active devices. The SpaceFibre link demonstrator was tested to transfer data at 2.5 Gb/s over 100 m with a bit error rate of less than 1.3middot10-14. Fiber-pigtailed modules were stressed with temperature variations from -40degC to +85degC, vibrations up to 30 g, and mechanical shocks up to 3900 g. The test results of 20 modules show that the SpaceFibre link is a promising candidate for the upcoming high-speed intrasatellite networks

Solder joint reliability in AgPt‐metallized LTCC modules

Purpose – To investigate the effect of the metallization and solder mask materials on the solder joint reliability of low temperature co‐fired ceramic (LTCC) modules.Design/methodology/approach – The fatigue performance of six LTCC/PCB assembly versions was investigated using temperature cycling tests in the −40‐125°C and 20‐80°C temperature ranges. In order to eliminate fatigue cracking in the LTCC module itself, large AgPt‐metallized solder (1 mm) lands with organic or co‐fired glaze solder masks, having 0.86‐0.89 mm openings, were used. The performance of these modules was compared to that of AgPd‐metallized modules with a similar solder land structure. The joint structures were analysed using resistance measurements, scanning acoustic microscopy, SEM/EDS investigation, and FEM simulations.Findings – The results showed that failure distributions with Weibull shape factor (β) values from 8.4 to 14.2, and characteristic life time (θ) values between 860 and 1,165 cycles were achieved in AgPt assemblies in...

A Multilayer LTCC Solution for Integrating 5G Access Point Antenna Modules

An integrated solution for the development of multilayer antenna modules for fifth-generation (5G) communications, based on low temperature cofired ceramic (LTCC), is presented. The design exploits the 3-D integration capabilities of the LTCC process, enabling the realization of a full-corporate feed network (CFN) in vertical configuration. A novel implementation of the CFN employing dielectric-embedded parallel plate waveguides (PPWs) is proposed. The PPW lines are delimited by via-rows. As opposed to standard substrate-integrated waveguide feed networks, guided fields are orthogonal to the via-rows and propagate along the vertical axis of the structure. The CFN feeds four long slots, without any coupling structure, and provides broadband operation. The final prototype comprises 18 LTCC tapes, with a total thickness of 3.4 mm. The measured -10-dB impedance bandwidth spans from 51.2 to 66 GHz (>25.2%). The module generates a fixed broadside beam, but multibeam operation in H-plane can be easily achieved. In the 50-66-GHz band, the peak gain is 14.25 dBi and the average first side-lobe level in H-plane is -20.6 dB. The proposed technology and the design concept are suited for highly integrated millimeterwave systems, such as access points in the future V-band high data-rate wireless networks.

Hermetic Fiber Pigtailed Laser Module Utilizing Passive Device Alignment on an LTCC Substrate

A hermetic fiber pigtailed laser module utilizing passive device alignment on a low-temperature cofired ceramics (LTCC) substrate is demonstrated. The 3-D shape of the laminated and cofired ceramic substrate provides the necessary alignment structures, including grooves and cavities, for the laser-to-fiber coupling. When the laser diode chip and component tolerances are tight enough, the passive alignment allows high coupling efficiency realizations of multimode fiber pigtailed laser modules. The ceramic substrate is intrinsically hermetic and it opens up the possibility to use the substrate as an integrated part of the hermetic module package. In our concept hermetic sealing is produced by utilizing a Kovar frame, which is soldered to an LTCC substrate. The Kovar frame has a hole for a fiber feed-through and a hermetic glass-metal seal between fiber and frame is processed using a glass preform. The module can be used as a transmitter in a laser pulse time-of-flight distance sensor and in this application it can be overdriven by a factor of 10. This means that the peak optical power in the pulses can be several dozen watts. The laser chip allows this kind of overdriving, due to the fact that the duty factor in the operation is only 0.0% at 2 kHz pulsing frequency, which leads to an average power of several milliwatts. The simulated nominal coupling efficiency between the 210 mum times 1 mum stripe laser and the 200/220 mum step index fiber (NA = 0.22) was 0.65. The measured coupling efficiency of the hermetically sealed prototypes varied from 0.14 to 0.64, where the average was 0.39. A leak rate of 1 times 10-7 . .. 8 times 10-7 [atm times cm3/s] was measured in the helium leak tests of the final operational prototypes, when the modules were tested according to MIL-STD-883F method 1014.9 specification. The rather high leak rate is mainly due to the helium absorbed by the fiber polymer buffer layer and rubber guard tube in the pressurization process. The leak rate for the dummy modules using a buffer stripped fiber without a rubber guard tube was 3 times 10-9 . .. 1 times 10-8 [atm times cm3/s]. The maximum allowed leak rate for this size of hermetic module is 1 times 10-7 [atm times cm3/s]. The background helium level before and after the tests was less than 3 times 10-10 [atm times cm3/s]. Measurements proved that the manufacturing procedure is capable of producing hermetic fiber pigtailed laser modules.

Cost-effective packaging of laser modules using LTCC substrates

The modeling, realization and characterization of photonic module based on the use of Low Temperature Co-fired Ceramics (LTCC) technology is reported. The 3D modeling of the system provides possibility to optimize structures, materials and components in order to achieve optimal performance for the final product and still maintain reasonably low fabrication costs. The cost-effectiveness in the product can be further optimized using an iterative optimization process, in which the effect of module manufacturing tolerances and assembly process tolerances is simulated by a VisVSA Monte-Carlo simulation. The tolerance distributions produced by a VisVSA simulation are used as input parameters together with optical component tolerances in an ASAP Monte-Carlo simulation, in which the final module optical performance distribution in simulated production is obtained. The module cost, performance and optical performance limited yield is possible to define with this iterative process. As an example of this kind of packaging modeling, we present a demonstrator module having a high-power multimode laser diode with a 1μm x 100μm emitting area coupled to a 62.5/125μm graded-index (NA=0.275) multimode fiber. The tolerance modeling results are verified by experimental characterization of the packaged prototypes. Measured coupling efficiencies were in good agreement with simulated ones, when the fiber NA was 0.2 or larger. The measured coupling efficiency, however, was 38% lower than simulated, when the fiber NA was 0.12. This was probably due to the laser mode structure difference between simulation model and reality. Coupling efficiency of 0.46 was obtained in a passively aligned demonstrator module, when the nominal value was 0.48.

Effect of ENIG deposition on the failure mechanisms of thermomechanically loaded lead‐free 2nd level interconnections in LTCC/PWB assemblies

Purpose – The purpose of this paper is to investigate the effect of electroless NiAu (ENIG) deposition on the failure mechanisms and characteristic lifetimes of three different non‐collapsible lead‐free 2nd level interconnections in low‐temperature co‐fired ceramic (LTCC)/printed wiring board (PWB) assemblies.Design/methodology/approach – Five LTCC module/PWB assemblies were fabricated and exposed to a temperature cycling test over a −40 to 125°C temperature range. The characteristic lifetimes of these assemblies were determined using direct current resistance measurements. The failure mechanisms of the test assemblies were verified using X‐ray and scanning acoustic microscopy, optical microscopy with polarized light, scanning electron microscope (SEM)/energy dispersive spectroscopy and field emission‐SEM investigation.Findings – A stable intermetallic compound (IMC) layer is formed between the Ni deposit and solder matrix during reflow soldering. The layer thickness does not grow excessively and the inte...

Wavelength-tunable laser module using low-temperature cofired ceramic substrates

We realized a prototype series of the 1550-nm band wavelength-tunable laser module. The edge-emitting Fabry-Perot diode laser operates in the short external cavity configuration and is tuned by a silicon surface micromachined Fabry-Peacuterot interferometer device. Low-temperature cofired ceramic (LTCC) substrate technology was used in the module packaging to enable the passive alignment of the photonic components. Low conductor resistance and dielectric loss, multilayer structures with fine-line capability, compatibility with hermetic sealing, and the ability to integrate passive electrical components (resistors, capacitors, and inductors) into the substrate make LTCC a useful technology for telecommunication applications. In addition, the fair match of the thermal expansion coefficient to optoelectronic chips reduces packaging-induced thermomechanical stresses. The precision three-dimensional (3-D) structures, such as cavities, holes, and channels manufactured in the ceramic parts, ease the packaging process via the passive assembly. The wavelength tuning range of the realized modules ranged from 8 to 19 nm and single-mode fiber-coupled output power was between 100 and 570 muW. The hybrid arrangement uses standard laser chips and, therefore, potentially provides a cost-effective and easily configurable solution for last-mile fiber optic communications

MEMS, MOEMS, RF-MEMS and photonics packaging based on LTCC technology

In order to fulfill the specifications of photonic systems, various optoelectronic chips, MEMS, MOEMS and RF-MEMS devices, micro-optical elements and integrated circuits needs to be integrated into functional components, modules and systems. The sub-systems of the photonic system must be fabricated by the use of cost-efficient, reproducible, well-established, high-volume manufacturing technologies. The functionality of the system is outlined by the combination of the functionalities of individual devices. The performance of the system, however, is defined by packaging and integration methods and configurations. Low temperature cofired ceramics (LTCC) is one of our key technology assets for photonics and MEMS/MOEMS/RF-MEMS packaging. In photonics integration, the tolerance of device alignment is the key issue of integration. In order to be able to use mass-manufacturing tools, the primary aim is to process 3D structures, such as, grooves, cavities, holes, bumps and alignment fiducials, which can be used for the passive alignment of devices. The tolerances of LTCC structures are typically ±5μm and in some specific cases ±2μm. Therefore, LTCC provides means for the passive alignment of multimode fiber as well as MOEMS devices. Thermal management by the use of thermal vias in LTCC is a well-established technique, and liquid cooling channels in the LTCC substrate provide efficient additional means for high-power laser cooling. When targeting for thermally controlled systems, thermal bridge structures can be used to isolate critical devices from main structures. LTCC provides inherently hermetic substrate allowing for the possibility to hermetic encapsulation. Hermetic fiber feed throughs and transparent windows can be integrated in LTCC structures. Cavities, channels and sealed gas cells can be fabricated, also. RF antennas and coil structures for electro-magnetic field control can be integrated in the LTCC substrate. Therefore, 3D packaging of MEMS, MOEMS and photonic devices is enabled by LTCC.

Optical transceivers for interconnections in satellite payloads

The increasing data rates and processing on board satellites call for the use of photonic interconnects providing high-bitrate performance as well as valuable savings in mass and volume. Therefore, optical transmitter and receiver technology is developed for aerospace applications. The metal-ceramic-packaging with hermetic fiber pigtails enables robustness for the harsh spacecraft environment, while the 850-nm VCSEL-based transceiver technology meets the high bit-rate and low power requirements. The developed components include 6 Gbps SpaceFibre duplex transceivers for intra-satellite data links and 40 Gbps parallel optical transceivers for board-to-board interconnects. Also, integration concept of interchip optical interconnects for onboard processor ICs is presented.