We show that full-image micro-PIV analysis in combination with images of transient particle motion is a powerful tool for experimental studies of acoustic radiation forces and acoustic streaming in microfluidic chambers under piezo-actuation in the MHz range. The measured steady-state motion of both large 5 microm and small 1 microm particles can be understood in terms of the acoustic eigenmodes or standing ultra-sound waves in the given experimental microsystems. This interpretation is supported by numerical solutions of the corresponding acoustic wave equation.

Nanotechnology is concerned with materials and systems whose structures and components exhibit novel physical, chemical, and biological properties due to their nanoscale size. This paper focuses on what is known as nanomedicine, referring to the application of nanotechnology to medicine. We consider the use and potentials of emerging nanoscience techniques in medicine such as nanosurgery, tissue engineering, and targeted drug delivery, and we discuss the ethical questions that these techniques raise. The ethical considerations involved in nanomedicine are related to risk assessment in general, somatic-cell versus germline-cell therapy, the enhancement of human capabilities, research into human embryonic stem cells and the toxicity, uncontrolled function and self-assembly of nanoparticles. The ethical considerations associated with the application of nanotechnology to medicine have not been greatly discussed. This paper aims to balance clear ethical discussion and sound science and so provide nanotechnologists and biotechnologists with tools to assess ethical problems in nanomedicine. INTRODUCTIONSignificant technological advances across multiple scientific disciplines continue to be proposed and validated. A revolution in health care and medical technology looms large on the horizon on the basis of the discipline of nanotechnology. Reports and articles often distinguish between nanoscience and nanotechnology. Nanoscience refers to the fundamental study of phenomena and the manipulation of matter at the atomic, molecular, and supramolecular level, where properties differ significantly from those at a larger scale. As such, nanoscience forms the knowledge base for nanotechnology. Nanotechnology refers to the design, characterisation, production, and application of structures, devices, and systems that have novel physical, chemical, and biological properties by controlling shape and size at the nanometre scale. Integration with other length scales will often be important to technological applications. In this paper we use the term nanotechnology as a collective term encompassing the various branches of both nanoscience and nanotechnology.Nanotechnology research has progressed rapidly over the last few years. Nanotechnology has become an interdisciplinary science where the disciplines of physics, chemistry, molecular biology, health sciences, and engineering collaborate, share knowledge, and build up a research culture across traditional disciplinary boundaries. Funding for nanotechnology has increased dramatically and nanotechnology has become a buzz word and is currently very visible compared to other fields of research. The vision of nanotechnology is to advance broad societal goals, such as improved comprehension of nature, increased productivity, better health care and to extend the limits of sustainable development and human potential [1]. A lot of developments in nanotechnology take years, but researchers and politicians claim that the process itself can lead to a new industrial revolution [2]. This paper fo...

DNA amplification using the polymerase chain reaction (PCR) is an important tool in biotechnology, pathogen surveillance in food, medical and forensic science etc. The PCR technique is now an important part of the research in and development of miniaturized biochemical analysis systems. However, reduced or no DNA amplification at all is an important challenge for microfabricated PCR devices due to a negative interaction between PCR chemicals and the surrounding environment, i.e. the materials encapsulating the PCR mix. Materials of special interest regarding PCR compatibility are silicon, glass and polymers, which are important in the fabrication of microelectromechanical systems (MEMS), micro total analysis systems (µTAS) and lab-on-a-chip (LOC) systems. The PCR inhibition effect is a particularly important phenomenon in microsystems due to an increased surface-to-volume ratio which enhances the possibility of interaction between the surfaces and ingredients in the PCR mixture. By proper surface treatment the PCR reaction can be facilitated and in this paper we present a systematic and quantitative study of the impact on the PCR compatibility of a chemical and a biological surface treatment. The chemical treatments are based on the silanizing agent dichlordimethylsilane [(CH 3 ) 2 SiCl 2 ]], while the biological treatment is based on the protein bovine serum albumin (BSA). We present a simple model system for the investigation of the PCR compatibility of three widely used materials in microfabrication, namely silicon, glass and SU-8. The impact on PCR performance, measured by means of PCR efficiency, of untreated as well as chemically and biologically treated materials is studied. We show a convenient method of assessing the PCR compatibility of silicon, glass and SU-8 with a degree of information not presented before.

The suitable optical properties of thiol-ene polymers combined with the ease of modifying their surface for the attachment of recognition molecules make them ideal candidates in many biochip applications. This paper reports the rapid one-step photochemical surface patterning of biomolecules in microfluidic thiol-ene chips. This work focuses on thiol-ene substrates featuring an excess of thiol groups at their surface. The thiol-ene stoichiometric composition can be varied to precisely control the number of surface thiol groups available for surface modification up to an average surface density of 136 ± 17 SH nm(-2). Biotin alkyne was patterned directly inside thiol-ene microchannels prior to conjugation with fluorescently labelled streptavidin. The surface bound conjugates were detected by evanescent wave-induced fluorescence (EWIF), demonstrating the success of the grafting procedure and its potential for biochip applications.

In this work, the bonding strength of microchips fabricated by thiol-ene free-radical polymerization was characterized in detail by varying the monomeric thiol/allyl composition from the stoichiometric ratio (1:1) up to 100% excess of thiol (2:1) or allyl (1:2) functional groups. Four different thiol-ene to thiol-ene bonding combinations were tested by bonding: (i) two stoichiometric layers, (ii) two layers bearing complementary excess of thiols and allyls, (iii) two layers both bearing excess of thiols, or (iv) two layers both bearing excess of allyls. The results showed that the stiffness of the cross-linked polymer plays the most crucial role regarding the bonding strength. The most rigid polymer layers were obtained by using the stoichiometric composition or an excess of allyls, and thus, the bonding combinations (i) and (iv) withstood the highest pressures (up to the cut-off value of 6 bar). On the other hand, excess of thiol monomers yielded more elastic polymer layers and thus decreased the pressure tolerance for bonding combinations (ii) and (iii). By using monomers with more thiol groups (e.g. tetrathiol versus trithiol), a higher cross-linking ratio, and thus, greater stiffness was obtained. Surface characterization by infrared spectroscopy confirmed that the changes in the monomeric thiol/allyl composition were also reflected in the surface chemistry. The flexibility of being able to bond different types of thiol-enes together allows for tuning of the surface chemistry to yield the desired properties for each application. Here, a capillary electrophoresis separation is performed to demonstrate the attractive properties of stoichiometric thiol-ene microchips.