Abstract: A method to measure the vibrational characteristics of an oscillating system (1) uses a control system (6, 7a, 7b, 7c). The oscillating system comprises a resonator, at least one vibration exciter and at least one sensor. The resonator is excited by the vibration exciter, and the motion of the resonator is measured by the sensor. The control system uses the sensor to control the motion of the resonator by the vibration exciter. The motion of the resonator is a superposition of at least two harmonic motions, and the control system comprises at least two subcontrollers (7a, 7b, 7c). Each harmonic motion is controlled independently by one of the subcontrollers. The harmonic motions are controlled by the subcontrollers simultaneously. A corresponding device is also disclosed.

Abstract: A method to measure the vibrational characteristics of an oscillating system (1) uses a control system (6, 7a, 7b, 7c). The oscillating system comprises a resonator, at least one vibration exciter and at least one sensor. The resonator is excited by the vibration exciter, and the motion of the resonator is measured by the sensor. The control system uses the sensor to control the motion of the resonator by the vibration exciter. The motion of the resonator is a superposition of at least two harmonic motions, and the control system comprises at least two subcontrollers (7a, 7b, 7c). Each harmonic motion is controlled independently by one of the subcontrollers. The harmonic motions are controlled by the subcontrollers simultaneously. A corresponding device is also disclosed.

Abstract: An acoustofluidic system comprises a substrate (10) having an essentially rectangular recess with side walls (33), wherein the recess provides a microfluidic channel (30) containing a fluid with droplets (31), and at least one electromechanical transducer (20) attached at the substrate (10) adapted to excite an acoustic field in said channel (30). The side walls (33) are hard acoustic walls having a high specific acoustic impedance mismatch to said fluid in the channel (30) and the transducer (20) is configured to excite bulk acoustic waves (BAW) as standing waves (32) of a predetermined harmonic resonance mode between said hard acoustic side walls (33), which couple into the fluid in the channel (30) exerting acoustic pressure on droplets (31) suspended in said fluid towards the pressure nodal line, pressure antinode line or centerline of the standing wave (32).

Abstract: A method of measuring properties of a fluid that uses a conductor electrically connected to a current source. A magnetic field is created about the conductor and the conductor is introduced into the fluid medium. A current waveform, having a frequency, is periodically passed through the conductor, so as to cause the conductor to move, due to force exerted on the conductor from interaction of the current and the magnetic field. The conductor movement is sensed, producing a sense signal that is amplified into an amplified sense signal. The phase relationship between the current waveform and the amplified sense signal is measured and the current waveform frequency is adjusted to create a phase lock loop. The frequency when the phase lock loop is in lock state is measured as the phase between the excitation and the measured sense signal is varied, and fluid properties are calculated from the measured frequencies.

Abstract: A system for measuring damping and that includes an oscillator that produces an excitation signal for a resonator that can be placed in a damping medium. A sensor produces a sensor signal responsive to resonator motion. Also, a timing circuit ensures that excitation and sensing occur during mutually exclusive periods. An amplifier responds to the sensor signal, producing an amplified sensor signal. A phase detector is adapted to measure the phase relationship between the excitation signal and the amplified sensor signal and a controller is responsive to the phase detector to adjust the excitation frequency of the excitation signal, to create a phase lock loop. An integrator receives the amplified signal during periods that are mutually exclusive to and interleaved with the excitation. This integrator produces an integrated DC and low frequency component of the amplified signal, which is subtracted from the input amplifier input.

Abstract: The invention relates to a method for determining the reactive state of a chemical reaction process in a reaction mixture (110), in particular an amplification reaction for nucleic acids. The method comprises a viscosity determination, which preferably uses a dynamic viscometer (1). The invention also relates to an improved dynamic viscometer (1) for carrying out said method. The viscometer is characterised by an appropriate choice of material for the resonator (101) and optimised geometric ratios.

Abstract: A method and a micropipetting apparatus is described for dispensing a liquid volume into a vessel via pipetting needle without any contact between the needle and a liquid contained in the vessel. The method comprises forming a drop at the delivery tip of the pipetting needle, the drop being retained at the tip by adhesion forces, and ejecting the drop from the tip of the pipetting needle by focusing at the tip of the pipetting needle a mechanical excitation wave applied at an excitation point at some distance from the tip of the pipetting needle. The apparatus comprises a pipetting needle, an electromechanical transducer mechanically connected with said pipetting needle for mechanically exciting the pipetting needle with a pulse of mechanical waves that propagate through the needle, and an electrical signal generator for generating an excitation pulse signal and for applying this signal to the electromechanical transducer.

Abstract: The invention covers the field of positioning of small particles (58, 59) in a fluid (55). Disclosed is a method by which small particles (58, 59) are positioned by a sound field. For generating the sound field an apparatus contains a plate (51) excited to vibrations by a transducer (52) and a reflecting body with a rigid surface (54). A mounting (53) holds the vibrating plate (51) and the transducer (52). The particles will be concentrated at predetermined positions either at the rigid surface of the reflecting body (58) or levitating in the fluid (59). Due to the fact that the sound waves are emitted by the vibrating plate particles can be positioned in entire area between the vibrating plate and the reflecting body.

Abstract: A level sensor apparatus is disclosed for detecting contact of a pipetting needle with a liquid contained in a vessel. The apparatus includes a sensor head made up of a pipetting needle, a needle holder, and an electromechanical transducer. The sensor head also has an associated mechanical resonance frequency. An electrical signal generator is used to generate a driving signal which when applied to the electromechanical transducer causes vibration of the pipetting needle at the resonance frequency. A measurement device is used to measure a parameter of a vibration signal indicative of the mechanical vibration of the pipetting needle when it is driven by the driving signal. An electronic circuit and associated computer software is provided to evaluate variation of the vibration signal with time and thus detect contact of the pipetting needle with a liquid contained in the vessel.

Abstract: The invention relates to a method for determining the reactive state of a chemical reaction process in a reaction mixture (110), in particular an amplification reaction for nucleic acids. Said method comprises a viscosity determination, which preferably uses a dynamic viscometer (1). The invention also relates to an improved dynamic viscometer (1) for carrying out said method. Said viscometer is characterised by an appropriate choice of material for the resonator (101) and optimised geometric ratios.

Abstract: A method and a micropipetting apparatus is described for dispensing a liquid volume into a vessel via pipetting needle without any contact between the needle and a liquid contained in the vessel. The method comprises forming a drop at the delivery tip of the pipetting needle, the drop being retained at the tip by adhesion forces, and ejecting the drop from the tip of the pipetting needle by focusing at the tip of the pipetting needle a mechanical excitation wave applied at an excitation point at some distance from the tip of the pipetting needle. The apparatus comprises a pipetting needle, an electromechanical transducer mechanically connected with said pipetting needle for mechanically exciting the pipetting needle with a pulse of mechanical waves that propagate through the needle, and an electrical signal generator for generating an excitation pulse signal and for applying this signal to the electromechanical transducer.

Abstract: A level sensor apparatus is disclosed for detecting contact of a pipetting needle with a liquid contained in a vessel. The apparatus includes a sensor head made up of a pipetting needle, a needle holder, and an electromechanical transducer. The sensor head also has an associated mechanical resonance frequency. An electrical signal generator is used to generate a driving signal which when applied to the electromechanical transducer causes vibration of the pipetting needle at the resonance frequency. A measurement device is used to measure a parameter of a vibration signal indicative of the mechanical vibration of the pipetting needle when it is driven by the driving signal. An electronic circuit and associated computer software is provided to evaluate variation of the vibration signal with time and thus detect contact of the pipetting needle with a liquid contained in the vessel.

Abstract: The invention covers the field of positioning of small particles (58, 59) in a fluid (55). Disclosed is a method by which small particles (58, 59) are positioned by a sound field. For generating the sound field an apparatus contains a plate (51) excited to vibrations by a transducer (52) and a reflecting body with a rigid surface (54). A mounting (53) holds the vibrating plate (51) and the transducer (52). The particles will be concentrated at predetermined positions either at the rigid surface of the reflecting body (58) or levitating in the fluid (59). Due to the fact that the sound waves are emitted by the vibrating plate particles can be positioned in entire area between the vibrating plate and the reflecting body.

Abstract: A resonator (1) is vibrating close to its resonance frequency. The vibration is excited by one or a first transducer (2) connected to an oscillator (11). The vibration is measured by the transducer (2) or a second transducer (3) and stabilized by a phase-locked feedback loop comprising a phase sensitive detector (33), a feedback controller (36), a phase shifter (17) and means (15) to evaluate the measured frequencies. In order to measure the damping of the resonator (1), the phase in the phase shifter (17) is alternately set to two different values. The difference between the frequencies corresponding to these two phase values is a measure for the damping of the system. One or more switches (19, 28, 27) and a gate generator (16) make sure that excitation and measurement do not occur at the same time. Thereby, any cross-talk between driving and sensing transducers is completely eliminated. Also, a single transducer can be used to both excite and measure the vibration.

Abstract: A resonator in the form of a cylindrical body is immersed in a fluid to be measured and excited by a piezoelectric transducer in the vicinity of its natural frequency. The vibration frequency is stabilized by a feedback loop. In that feedback loop a phase shift is introduced which can be switched between to discrete values. The resulting difference in frequency of oscillation of the resonator is proportional to the damping ratio of the resonator and is, therefore, a measure for the viscosity of the fluid. The natural frequency of the piezoelectric transducer is substantially higher than the natural frequency of the resonator, and the oscillation of the resonator is mechanically isolated from the housing by an inertial mass - spring arrangement with low natural frequency.