Göran Stemme

Bio: Göran Stemme is an academic researcher from Royal Institute of Technology. The author has contributed to research in topics: Wafer & Wafer bonding. The author has an hindex of 61, co-authored 466 publications receiving 13831 citations. Previous affiliations of Göran Stemme include Chalmers University of Technology.

A valveless diffuser/nozzle-based fluid pump

Abstract: A new valveless fluid pump has been designed and tested. The pump consists of two fluid diffuser/nozzle elements on each side of a chamber volume with an oscillating diaphragm. The vibrating diaphragm produces an oscillating chamber volume, which together with the two fluid-flow-rectifying diffuser/nozzle elements, creates a one-way fluid flow. A micropump prototype with a chamber diameter of 19 mm with conical diffuser/nozzle elements has been built and tested. The maximum liquid flow rate is 16 ml/min and the maximum pump pressure is 2 m H 2 O. The pump frequency is of the order of 100 Hz.

Adhesive wafer bonding

Abstract: Wafer bonding with intermediate polymer adhesives is an important fabrication technique for advanced microelectronic and microelectromechanical systems, such as three-dimensional integrated circuits, advanced packaging, and microfluidics. In adhesive wafer bonding, the polymer adhesive bears the forces involved to hold the surfaces together. The main advantages of adhesive wafer bonding include the insensitivity to surface topography, the low bonding temperatures, the compatibility with standard integrated circuit wafer processing, and the ability to join different types of wafers. Compared to alternative wafer bonding techniques, adhesive wafer bonding is simple, robust, and low cost. This article reviews the state-of-the-art polymer adhesive wafer bonding technologies, materials, and applications.

Resonant silicon sensors

Abstract: This paper is a review of the design and fabrication of resonant sensors that are based on resonating silicon structures. Some of the design aspects that control the performance of the resonator sensor are analysed. The most important aspects are: resonator materials, fabrication technology, type of resonator, mode of vibration, quality of vibration and temperature stability. Q-factor-reducing damping factors are discussed and the different techniques that are available for excitation and detection of the vibration of the resonator are described. Descriptions of published resonant silicon sensors are presented.

A valve-less planar fluid pump with two pump chambers

Abstract: A new planar fluid pump based on the valve-less diffuser/nozzle pump principle is presented. The pump consists of two pump chambers, each with two flow rectifying diffuser/nozzle elements with rectangular cross sections, one at the inlet and one at the outlet. The pump chambers are arranged in parallel for high pump flow. Each pump chamber has two piezoelectrically vibrated diaphragms. The planar pump is fabricated in brass with a total thickness of 1 mm. The pump chamber diameter is 13 mm and the diffuser/nozzle element neck dimensions are 0.3×0.3 mm. Simplified theoretical analyses of the maximum pump flow and resonance frequency are given. The flow rectifying ability of the diffuser/nozzle elements is demonstrated in a stationary flow situation and the pump performance is verified in two different pump mode configurations: anti-phase and in-phase chamber volume excitation. The measurements in the anti-phase mode show pump flows and pump pressures which are more than twice as high as those of the in-phase oscillation mode. The anti-phase mode has a pump capacity of about 16 ml/min and a maximum pump pressure of about 1.7 m H2O with the pump diaphragm vibration frequency set to the pump resonance frequency of 540 Hz.

A packaged optical slot-waveguide ring resonator sensor array for multiplex label-free assays in labs-on-chips

Abstract: We present the design, fabrication, and characterisation of an array of optical slot-waveguide ring resonator sensors, integrated with microfluidic sample handling in a compact cartridge, for multiplexed real-time label-free biosensing. Multiplexing not only enables high throughput, but also provides reference channels for drift compensation and control experiments. Our use of alignment tolerant surface gratings to couple light into the optical chip enables quick replacement of cartridges in the read-out instrument. Furthermore, our novel use of a dual surface-energy adhesive film to bond a hard plastic shell directly to the PDMS microfluidic network allows for fast and leak-tight assembly of compact cartridges with tightly spaced fluidic interconnects. The high sensitivity of the slot-waveguide resonators, combined with on-chip referencing and physical modelling, yields a volume refractive index detection limit of 5 × 10−6 refractive index units (RIUs) and a surface mass density detection limit of 0.9 pg mm−2, to our knowledge the best reported values for integrated planar ring resonators.

Microfluidics: Fluid physics at the nanoliter scale

Abstract: Microfabricated integrated circuits revolutionized computation by vastly reducing the space, labor, and time required for calculations. Microfluidic systems hold similar promise for the large-scale automation of chemistry and biology, suggesting the possibility of numerous experiments performed rapidly and in parallel, while consuming little reagent. While it is too early to tell whether such a vision will be realized, significant progress has been achieved, and various applications of significant scientific and practical interest have been developed. Here a review of the physics of small volumes (nanoliters) of fluids is presented, as parametrized by a series of dimensionless numbers expressing the relative importance of various physical phenomena. Specifically, this review explores the Reynolds number Re, addressing inertial effects; the Peclet number Pe, which concerns convective and diffusive transport; the capillary number Ca expressing the importance of interfacial tension; the Deborah, Weissenberg, and elasticity numbers De, Wi, and El, describing elastic effects due to deformable microstructural elements like polymers; the Grashof and Rayleigh numbers Gr and Ra, describing density-driven flows; and the Knudsen number, describing the importance of noncontinuum molecular effects. Furthermore, the long-range nature of viscous flows and the small device dimensions inherent in microfluidics mean that the influence of boundaries is typically significant. A variety of strategies have been developed to manipulate fluids by exploiting boundary effects; among these are electrokinetic effects, acoustic streaming, and fluid-structure interactions. The goal is to describe the physics behind the rich variety of fluid phenomena occurring on the nanoliter scale using simple scaling arguments, with the hopes of developing an intuitive sense for this occasionally counterintuitive world.

Engineering flows in small devices

Abstract: Microfluidic devices for manipulating fluids are widespread and finding uses in many scientific and industrial contexts. Their design often requires unusual geometries and the interplay of multiple physical effects such as pressure gradients, electrokinetics, and capillarity. These circumstances lead to interesting variants of well-studied fluid dynamical problems and some new fluid responses. We provide an overview of flows in microdevices with focus on electrokinetics, mixing and dispersion, and multiphase flows. We highlight topics important for the description of the fluid dynamics: driving forces, geometry, and the chemical characteristics of surfaces.

Microfluidic large scale integration

Abstract: High-density microfluidic chips contain plumbing networks with thousands of micromechanical valves and hundreds of individually addressable chambers. These fluidic devices are analogous to electronic integrated circuits fabricated using large scale integration (LSI). A component of these networks is the fluidic multiplexor, which is a combinatorial array of binary valve patterns that exponentially increases the processing power of a network by allowing complex fluid manipulations with a minimal number of inputs. These integrated microfluidic networks can be used to construct a variety of highly complex microfluidic devices, for example the microfluidic analog of a comparator array, and a microfluidic memory storage device resembling electronic random access memories.