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Introduction
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September 1983 - January 1992
Publications
Publications (82)
A 200 mm processing platform for the large-scale production of graphene field-effect transistor-quantum dot (GFET-QD) hybrid photodetectors is demonstrated. Comprehensive statistical analysis of electric data shows a high yield (96%) and low variation of the 200 mm scale fabrication. The GFET-QD devices deliver responsivities of 10${^5}$ - 10${^6}$...
Machine vision is a driver for novel imaging solutions covering wavelength range from visible to SWIR light. Emberion produces high‐performance industrial cameras based on its own monolithically CMOS integrated image sensors that are built on two unique innovations: 1) using a combination of colloidal quantum dots and graphene, and 2) optimising th...
Colloidal quantum dots (QDs) combined with a graphene charge transducer promise to provide a photoconducting platform with high quantum efficiency and large intrinsic gain, yet compatible with cost-efficient polymer substrates. The response time in these devices is limited, however, and fast switching is only possible by sacrificing the high sensit...
An apparatus including a substrate and an active material, the substrate including an open interconnected wall structure of electrically conductive material having one or more pores, the open interconnected wall structure providing the substrate upon which the active material is supported, wherein the active material includes an electrically insula...
An apparatus including a layer of electrically conductive material with an open interconnected wall structure of electrically conductive material formed thereon, the open interconnected wall structure having a gyroid structure including one or more open pores into which an active material for use in generating and/or storing electrical charge can b...
An electrode, the electrode including a conducting layer configured to act, in use, as a charge collector to provide an electrical path for generated and/or stored charge through the conducting layer; a barrier layer, the barrier layer configured to cover a portion of a surface of said conducting layer such that, when the electrode is in contact wi...
An apparatus including a capacitance touch sensor arrangement configured to have a variable capacitance that varies when a user finger touches the capacitance touch sensor arrangement; and at least one variable resistor sensor integrated within the capacitance touch sensor arrangement wherein the variable resistor sensor has a variable resistance t...
Novel computing technologies that imitate the principles of biological neural systems may offer low power consumption along with distinct cognitive and learning advantages. The development of reliable memristive devices capable of storing multiple states of information has opened up new applications such as neuromorphic circuits and adaptive system...
We present the science and technology roadmap (STR) for graphene, related two-dimensional (2d) crystals, and hybrid systems, targeting an evolution in technology, with impacts and benefits reaching into most areas of society. The roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research...
An apparatus includes an optically transparent electrode configured to provide transcutaneous electrical nerve stimulation to a user contacting a portion of an exterior surface of the apparatus proximal to the optically transparent electrode.
An apparatus including a body portion having a surface; at least one feedback electrode configured to provide to a user a feedback stimulus when the user contacts the surface; and a touch sensor arrangement for discriminating different user contacts on the surface.
A trap Including: an inlet configured to receive a fluid conveying nanostructures; ionic liquid configured to trap the nanostructures; and an outlet for the fluid.
We compare three different carbon nanoarchitectures used to produce standard coin cell batteries: graphene monolayer, graphite paper and graphene foam. The batteries' electrochemical performances are characterised using cyclic voltammetry, constant-current discharge and dynamic galvanostatic techniques. Even though graphene is the fundamental build...
A battery cell including: an anode configured to operate as a source of cations during discharge of the battery cell; and an electrolyte configured to transport the cations from the anode to the a cathode during discharge of the battery cell, wherein the cathode includes material that is configured to enable the reversible insertion of transported...
Sensors allow an electronic device to become a gateway between the digital and physical worlds, and sensor materials with unprecedented performance can create new applications and new avenues for user interaction. Graphene oxide can be exploited in humidity and temperature sensors with a number of convenient features such as flexibility, transparen...
The ever increasing demand for storage of electrical energy in portable electronic devices and electric vehicles is driving technological improvements in rechargeable batteries. Lithium (Li) batteries have many advantages over other rechargeable battery technologies, including high specific energy and energy density, operation over a wide range of...
The energy and power requirements of portable electronic devices and electric vehicles are ever increasing, driving research into novel battery structures with increased volumetric energy and power densities. Existing energy storage technologies cannot satisfy both of these requirements. There are many reports on the application of graphene in batt...
A rollable and all-solid-state textile lithium battery based on fabric matrix and polymer electrolyte that allows flexibility and fast-charging capability is reported. When immerged into poly(3,4-ethylenedioxythiophene) (PEDOT) nano-emulsion inks, an insulating fabric is converted into a conductive battery electrode for a fully solid state lithium...
We report the first successful application of an ordered bicontinuous double-gyroid vanadium pentoxide network in an electrochromic supercapacitor. The freestanding vanadia network was fabricated by electrodeposition into a voided block copolymer template that had self-assembled into the double-gyroid morphology. The highly ordered structure with 1...
Graphene-based materials are intriguing from the perspective of fundamental science and technology because they are non-toxic, chemically and thermally tolerant, and mechanically robust. Graphene exhibits superior electrical conductivity, high surface area and a broad electrochemical window that may be particularly advantageous for their applicatio...
Graphite was electrochemically exfoliated in mixtures of room temperature ionic liquids and deionized water containing lithium salts to produce functionalized graphenes and such an electrochemical exfoliation technique can be directly used in making primary battery electrodes with significantly enhanced specific energy capacity.
We examine possibilities for making advances in nanocomputing by bringing in ideas from the field of machine learning. The potential from combining machine learning with nanocomputing seems to be underutilized. We review three complementary approaches. Firstly, machine learning can be used in the different phases of developing complicated nanocompu...
Different formulations of solution-processable graphene have been characterised as electrode materials for use in electrochemical energy storage devices. Graphene was fabricated by chemical reduction of exfoliated graphene oxide (GO), and modified with either p-type (e.g. polyaniline) or n-type anionic groups (poly(styrenesulfonate) (PSS−) and poly...
Different graphene inks have been synthesized by chemical methods. These uniform dispersions were stabilized by various functional groups such as room temperature ionic liquid, polyaniline, polyelectrolyte (poly[2,5-bis(3-sulfonatopropoxy)-1,4-ethynylphenylene-alt-1,4-ethynylphenylene] sodium salt) and poly(styrenesulfonate) (PSS). The dispersions...
Photoelectrochemistry is attracting extensive attention from scientists worldwide for its use in converting light energy into electricity in electrochemical photovoltaic cells, the most common form of which, dye sensitized solar cells (DSSCs), can offer both flexibility and transparency. Their efficiencies are now comparable with amorphous silicon...
Polyaniline (PANI) nanobrushes were synthesized by template-free electrochemical galvanostatic methods. When the same method was applied to the carbon nanohorn (CNH) solution containing aniline monomers, a hybrid nanostructure containing PANI and CNHs was enabled after electropolymerization. This is the first report on the template-free method to m...
Explore the potential for nanotechnologies to transform future mobile and Internet communications. Based on a research collaboration between Nokia, Helsinki University of Technology, and the University of Cambridge, here leading researchers review the current state-of-the art and future prospects for: • Novel multifunctional materials, dirt repelle...
Mobile communication and the Internet The Internet has created in only one decade a global information network that has become the platform for communication and delivering information, digital content and knowledge, enabling commercial transactions and advertising, creating virtual communities for cocreating and sharing their content, and for buil...
Ubiquitous sensing, actuation, and interaction The London of 2020, as described in Chapter 1, will have conserved most of its old character but it will also have become a mixed reality built upon the connections between the ubiquitous Internet and the physical world. These connections will be made by a variety of different intelligent embedded devi...
The general mechanism of chemical sensing is based on molecular recognition linked to different transduction strategies based on electrochemical, optical, gravimetric or thermal effects that can convert the signal to digital information. Electrochemical sensors support accurate, fast, and inexpensive analytical methods with the advantages of being...
The mobile phone is becoming a trusted personal device with fundamental new capabilities. New form factors of mobile device and their user interfaces require new concepts for transformable mechanics. Integration of electronics and user interface functions into structural components will be necessary. Modular architecture will enable use of optimal...
This paper describes a new strategy to make a full solid-state, flexible, dye-sensitized solar
cell (DSSC) based on novel ionic liquid gel, organic dye, ZnO nanoparticles and carbon
nanotube (CNT) thin film stamped onto a polyethylene terephthalate (PET) substrate.
The CNTs serve both as the charge collector and as scaffolds for the growth of ZnO
n...
This paper reviews the expected wide and profound impact of nanotechnology for future wireless devices and communication technologies.
Previously, steady-state measurement methods have been used to characterize micro-electro-mechanical (MEM) capacitor performance during reliability testing and the testing has concentrated on detecting failure of the device. This paper shows that the dynamic performance of the MEM capacitor changes during continuous actuation. Therefore, continuous...
This paper presents a novel temperature-compensated two-state microelectromechanical (MEM) capacitor. The principle to minimize temperature dependence is based on geometrical compensation and can be extended to other devices such as MEM varactors. The compensation structure eliminates the effect of intrinsic and thermal stress on device operation....
This paper reports on the modeling and fabrication of a truly three-dimensional high-quality-factor toroidal inductor using polymer replication processes. The critical dimensions are in the micrometer range, and the applied manufacturing method is based on polymer replication. Electrical measurements show that the inductor with an inductance of 6.0...
The packaging of radio frequency microelectromechanical systems (RF MEMS) for mobile communications is discussed. The requirements of the packaging solutions for microsystems are hermetic sealing, stability of the controlled gas pressure in some applications, thermal and mechanical stability and the use of materials and designs to achieve high qual...
This paper describes the design principles of electrostatically actuated microelectromechanical capacitors. Key properties, such as capacitance tuning range, quality factor (Q), different control methods, thermal stability, effect of radio frequency signal on capacitance and gas damping are examined. Experimental devices were designed and fabricate...
A compact model for a capacitive RF MEM switch with damping is
presented. The damping model is based on analytic expressions for flow
resistances due to the rarefied air flow in the gap and in the
perforation holes. The complete switch model is constructed of elements
resulting from the discretization of the beam deflection equation and
has been im...
A simulation model for static analysis of a doubly supported capacitive MEMS RF switch has been con-structed using electrical equivalencies. Energy-conserving large-displacement macro models for beam deflection, gap capacitance, electrostatic force, and mechanical con-tact are utilized. A one-dimensional finite-difference ap-proach is utilized. The...
We describe an angular rate sensor based on bulk micro-machining
of silicon. A silicon beam suspended on two sets of torsion springs has
two orthogonal degrees of freedom for angular motion. The Coriolis force
induced by external rotation modulates the coupling between the two
modes which is then converted to a voltage output by an electro
mechanic...
A simulation model for an angular rate sensor, a gyroscope, is presented. The device is based on a micromechanical dual torsional mass system which is actuated electrostatically and sensed capacitively. Model equations describing a dynamic, non-linear system are first presented and then realized as an electrical equivalent circuit. The vibrational...
An electrical component model for a micromechanical accelerometer
is presented. In addition to the varying capacitances, the motion of the
seismic mass and the damping gas films are described by means of an
electrical equivalent circuit. The resulting model can be analyzed
together with the interfacing electronics utilizing all analysis modes
avail...
We present a new electric equivalent circuit for the forces created by a squeezed gas film between vertically moving planar surfaces. The model is realized with frequency-dependent resistors and inductors. Circuit analysis tools are applied to calculate the response of a micromechanical silicon capacitive accelerometer in both the frequency and the...
The authors have carried out extensive mappings of the DC
characteristics and flux noise of an integrated, DC superconducting
quantum interference device (SQUID) magnetometer as functions of bias
current and applied flux. The open-loop white flux noise at 1 kHz
measured without flux modulation is
Φ<sub>n</sub><7×10<sup>-7</sup> Φ<sub>0</sub>/√Hz
th...
Practical thin‐film dc superconducting quantum interference devices (SQUIDs) are often built with an integrated input coil which leads to the formation of various parasitic elements. We have designed and fabricated several square washer‐shaped dc SQUID test devices with various amounts of parasitic capacitance formed by covering the washer slits wi...
We have designed and fabricated a very low noise integrated dc Superconducting QUantum Interference Device (SQUID) magnetometer on a 4×4 mm2 chip. The white flux noise at 1 kHz is \(6 \times {10^{ - 7}}{\Phi _0}/\sqrt {Hz} \). This corresponds to a flux density noise of \(3.4\;fT/\sqrt {Hz} \) and a coupled energy resolution of 32 h. The 1/f noise...
We have designed and fabricated a low‐noise dc superconducting quantum interference device (SQUID) magnetometer that is integrated on a 4×4 mm<sup>2</sup> chip. The white flux noise of the magnetometer measured in a flux‐locked‐loop mode using simple, direct‐coupled electronics with additional positive feedback (APF) is 6.4×10<sup>-7</sup> Φ 0 /√Hz...
A 37-channel DC SQUID magnetometer system has been built for
biomagnetic studies. The SQUID loop of each magnetometer serves as the
active sensing element, thereby eliminating the need for flux coupling
circuits. The magnetometers are located ≃3 cm above the outer dewar
bottom. The SQUIDs are directly coupled to a highly simplified readout
ele...
An optimization procedure is presented which is used to design two
types of ultralow-noise DC superconducting quantum interference devices
(SQUIDs) with integrated flux coupling circuits, a magnetometer, and a
gradiometer. Essential to this design approach is the reduction of the
parasitic capacitance, the choice of a layout which moves the input c...
A directly coupled DC SQUID magnetometer with very simple feedback
electronics is presented. The magnetometer has been integrated on a
7.2×7.2 mm<sup>2</sup> chip and fabricated using a four-level
Nb/Si<sub>x</sub>N<sub>y</sub>/Nb process. Eight pickup loops are
connected in parallel to directly form the SQUID inductance of about 0.4
nH which leads...
The effect of parasitic capacitance C <sub>p</sub> on DC
SQUID characteristics and noise performance has been studied using a
test structure consisting of 11 identical SQUID washers with Nb films of
various widths covering the slit. The measured I - V
characteristics are in good agreement with simulations based on a simple
lumped circuit model. Th...
Low noise dc SQUIDs based on a Nb/Al-AlOx/Nb Josephson junction technology have been developed. The design has been optimized for improved control of the resonances. An eight-level process has been used for device fabrication. Flux noise levels of \(2.8 \times {10^{ - 7}}{\Phi _0}/\sqrt {Hz} \) at 1 kHz and \(1.5 \times {10^{ - 6}}{\Phi _0}/\sqrt {...
Publisher Summary The superconducting quantum interference device (SQUID) offers unrivalled sensitivity for the measurement of low-frequency magnetic fields. The chapter reviews the operation of rf and dc SQUIDs, stressing, in particular, the theoretical understanding of complete SQUID circuits. This is necessary for the design of practical devices...
We present a novel formulation for SQUID operation, which enables us to evaluate and compare the sensitivity and applicability of different devices. SQUID magnetometers for low-frequency applications are analyzed, taking into account the coupling circuits and electronics. We discuss nonhysteretic and hysteretic single-junction rf SQUIDs, but the ma...
A high-sensitivity microwave SQUID (superconducting quantum
interference device), suitable for RF attenuation measurements, is
constructed taking advantage of the low density of states of current
carriers in high- T <sub>c</sub> materials. The dynamics, the
noise properties, and the sensitivity of the microwave SQUID are
theoretically analyzed. The...
Recursive PASCAL procedures for generating the molecular topology from input coordinates and for performing extensive grid-searches using a very reasonable amount of CPU time are presented. Attention is paid to the performance of the algorithms to some test cases and the increased efficiency is discussed. The relevance of this approach to the study...
The dynamics of the dc-SQUID in the presence of a signal coil was studied. The signal coil creates an additive parasitic capacitance between the junctions and its self-resonance imports new features to the SQUID dynamics. Our results suggest that if a SQUID with smooth characteristics and low noise properties is desired, all the resonances present...
It is argued on the basis of computer simulations that points with multiple modes in the dc superconducting quantum interference device (SQUID) dynamics should be avoided as operating points of a flux detector.
Report 1-86. Proc. of the XX ann. conf. of the Finnish Physical Society. Tampere, 6 - 8 Febr. 1986, 7:14
A Fortran V (Univac) program is described which calculates molecular conformational energies on the basis of user-selected intramolecular potential energy functions. The algorithm presented here is designed to perform the computation of the conformational partition and therefore it can be used for the prediction of experimentally available quantiti...
Magnetic signals produced by voluntary eye blinking were recorded. The maximal signals were found over the posterior parts of the orbits. The polarity of the signal reversed over each eye and in the frontal midline. The amplitude increases with light and amplitude decreases with darkness were similar in the electrical and magnetic blink and eye mov...
Report Series Turku-FTL, R116
Convention on Radio Science Abstracts of Papers. Otaniemi, 17 - 18 Oct. 1988
Proc. 22. Annu. Finnish Physical Society. 22. Fysiikan päivät. Jyväskylä, 24.- 26.3.1997
Convention of Radio Science Abstracts of Papers. Otaniemi, 17 - 18 Oct. 1988
Conf. Precision Electromagnetic Measurements 1988, CPEM '88. Tsukuba, Japan, 7 - 10 June 1988, 59 - 60
Proc. 22. Annu. Finnish Physical Society. 22. Fysiikan päivät. Jyväskylä, 24.- 26.3.1997
Proc. XXIII annu. conf. Finnish Physical Society. Finland, Haikko, 30 March - 1 April 1989, 7:20
