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EP2796208A1 - Procédé pour commander une cellule acoustique - Google Patents

Procédé pour commander une cellule acoustique Download PDF

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Publication number
EP2796208A1
EP2796208A1 EP13164759.6A EP13164759A EP2796208A1 EP 2796208 A1 EP2796208 A1 EP 2796208A1 EP 13164759 A EP13164759 A EP 13164759A EP 2796208 A1 EP2796208 A1 EP 2796208A1
Authority
EP
European Patent Office
Prior art keywords
phi
acoustic
cos
frequency
power
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13164759.6A
Other languages
German (de)
English (en)
Inventor
David Sergeant
Jeremie Cubeta
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ipratech SA
Original Assignee
Ipratech SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ipratech SA filed Critical Ipratech SA
Priority to EP13164759.6A priority Critical patent/EP2796208A1/fr
Priority to PCT/EP2014/057685 priority patent/WO2014173745A2/fr
Publication of EP2796208A1 publication Critical patent/EP2796208A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B06GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06BMETHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/0207Driving circuits
    • B06B1/0223Driving circuits for generating signals continuous in time
    • B06B1/0238Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave
    • B06B1/0246Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave with a feedback signal

Definitions

  • the present invention is related to a method for regulating the power and frequency of an acoustic field applied to an acoustic cell. More particularly, the present invention is related to the regulation of the control parameters used in an acoustic cell for separating particles such as biological cells in a liquid medium.
  • the present invention is also related to an acoustic cell to be controlled by the method of the invention.
  • a second strategy is based upon centrifugation.
  • the developed systems are mechanically complex, and it is difficult to produce disposable parts that can provide continuous separation by centrifugation.
  • acoustic separation was developed, to solve some of those problems.
  • an acoustic field is applied to a resonant cavity, with the acoustic wave nodes and antinodes planes parallel to the direction of the liquid flow to be filtered.
  • the particles are trapped in the antinodes planes and accumulate in those planes.
  • the particles can then be collected by periodically stopping the acoustic field and reversing the flow or let the particles sediment by gravity to a collecting tank.
  • the separation cell consist in a resonating cavity, comprising to opposed parallel plane surfaces, at least one of them being coupled to a piezoelectric transducer for producing the acoustic field.
  • Document EP0633049 discloses such an acoustic cell, and the corresponding filtering method.
  • Document EP0633049 describes how to calculate the theoretical resonance frequencies of typical cavities, but, such frequencies are usually not perfectly stable. For example, small dimensional variation of the plate distance, particle density, and fluid temperature are known to have an important impact on the sound speed and therefore on the resonance frequency.
  • the frequency is usually adapted in a closed loop regulation, by maximising the power transfer to the fluid.
  • the power needs to be sufficient at any time, so that the signal arising from the coupling with the filtered fluid is sufficient. Therefore, in such frequency tracking method, the power is permanently maintained higher than what is really needed for maintaining resonance conditions.
  • An aim of the invention is to provide a method for continuously regulating both frequency and power applied to the piezoelectric transducer(s) of an acoustic cell wherein the injected power is minimised, and the resonance conditions are optimised.
  • the method of the invention aims to provide a regulating method of both power and frequency applied to an acoustic cell adapted to continuously filter particles from a fluid having varying physical properties such as sound speed, compressibility and density.
  • An aim of the invention is to provide a regulating method sufficiently robust to be used for controlling disposable acoustic cells having broad dimensional tolerances.
  • the present invention is related to an iterative method for controlling an acoustic cell separating dispersed particles in a liquid medium, said acoustic cell comprising two opposed plates delimiting a resonating cavity filled with said liquid medium, at least one of the opposed surfaces comprising a piezoelectric transducer coupled to an electrical power generator for producing ultrasonic waves in said resonating cavity, said method comprising the steps of:
  • the present invention is also related to a disposable acoustic cell for separating particles dispersed in a liquid medium, said acoustic cell comprising a polymeric housing and two opposed plates, said polymeric housing and said opposed plates defining an enclosure for receiving a liquid comprising particles to be separated from said liquid by an acoustic wave field, a piezoelectric transducer being fixed on at least one of said opposing plates for applying the acoustic wave field between said plates.
  • Fig. 1 represents a side view of an example of acoustic cell according to the invention.
  • Fig. 2 represents a top view of a cross section along the A-A' plane of the acoustic cell of fig.1
  • Fig. 3 represents a schematic view of the regulating system of the invention.
  • the present invention is related to a method for controlling the acoustic power and frequency injected in an acoustic cell.
  • the acoustic cell comprises two opposed plates 5 defining a resonant cavity.
  • An acoustic field is applied to the cavity by means of at least one piezoelectric 4 transducer fixed on the external surface of at least one of the opposed plates 5.
  • the plate without transducer act as a mirror.
  • a piezoelectric transducer is fixed on both plates. This allows the use of larger cells for a given injected power by each piezoelectric transducer, thereby reducing local heat dissipation.
  • the plates have Knopp hardness HK 0.1/20 higher than 300, preferably higher than 480, and a density higher than the liquid density.
  • This can be for example silicate glass, preferably borosilicate glass.
  • the lateral sides of the acoustic cells comprises transparent viewing windows 3, for visual inspection of the filtering process (i.e. particles/cells agregation).
  • An acoustic absorbing medium 10 is advantageously coated on those viewing window, in order to avoid complex reflexions on the windows, perturbing the resonant acoustic field. Silicone rubber is particularly adapted as absorbing medium.
  • the inner dimensions of the cell, and the thickness of the plate are selected so that they are multiples of half of the wavelength of the injected sound.
  • the properties of the liquid medium are varying around average values for example due to local temperature increase, particles density and composition of the liquid.
  • acoustic cells preferably disposable.
  • the dimensional tolerances are usually much broader than the tolerance obtained on expensive non disposable cells.
  • the system can be calibrated once, reusing initially measured resonance frequency in subsequent uses. This is not realistically feasible in the case of disposable acoustic cells.
  • the method of the invention does not only adapt the frequency to the resonance conditions, but also minimise the power injected in the liquid medium.
  • phase shift phi between the applied electrical potential and the resulting electrical current is minimum.
  • a convenient measurement of said phase shift phi is the measurement of the cosine of phi (cos(phi)), cos(phi) being maximum at resonance.
  • the method of the invention is preferably controlled by a numerical processor controlling the frequency of a wave generator and the gain of an amplifier (power control) downstream of the wave generator, the piezoelectric transducer being connected to the output of the amplifier, as represented in Fig. 3 .
  • an initial frequency is used to generate an acoustic field in the acoustic cell, and the gain of the amplifier is slowly increased until cos(phi) reaches a predetermined value.
  • This step permits to obtain a sufficient signal to begin the tracking of the resonance frequency even in the case of badly known dimensions of the acoustic cell (disposable acoustic cell).
  • the frequency is iteratively varied to increase cos(phi) and the power is decreased, so that in stable conditions, the resonance is maintained at the minimum feasible power input.
  • the variation of the power and frequency is performed according to the following sequential steps:
  • the determination of the direction of the gradient of cos(phi) can for example be determined by performing the minimum possible decrement of frequency, then measuring cos(phi), if cos(phi) has increased, this means that the gradient is negative and the frequency is decreased before getting back to step b, else, performing a double increment of the frequency, if cos(phi) has increased, it means that the gradient is positive, and the frequency is increased before getting back to step b. If cos(phi) has not increased in both directions (increment or decrement) the gradient is considered as being zero, and the frequency is maintained at its previous value before getting to step b.
  • Sequences without acoustic field are used at periodical time in order to collect the particles agglutinated at the wave antinodes, the particles sedimenting when the acoustic field is stopped. Those stopping sequences are also used to perform a subsequent optimisation of the control parameters.
  • the initial frequency applied to the transducers is determined by a dichotomic numerical method.
  • a lag time of at least 1 ms, preferably 10ms, more preferably 100ms is used to let the system equilibrate after any frequency or power changes, before cos(phi) measurements.
  • the method of the invention has been tested on disposable acoustic cells of the type represented in fig. 1 and 2 .
  • the plates defining the resonant cavity where separated by 34mm.
  • the plates themselves where made of glass plates of 1,2mm thickness.
  • the plates dimensions where 41mm height and 31mm width.
  • the wave generator was operated between 2,18 and 2.3MHz, the power control of the gain of the amplifier was performed by a step by step potentiometer, the power varying from 0 to 15W.
  • the predetermined threshold of step b was 0,3538 and was identical to the predetermined value used in the initial step (see initial step hereabove).
  • Typical operating cycle time is about 45s, separated by 5s lag time between each operating cycles.
  • the system has shown robust behaviour in finding resonance conditions in disposable acoustic cells and in changing conditions, giving rise to better filtering conditions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Micro-Organisms Or Cultivation Processes Thereof (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)
EP13164759.6A 2013-04-22 2013-04-22 Procédé pour commander une cellule acoustique Withdrawn EP2796208A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP13164759.6A EP2796208A1 (fr) 2013-04-22 2013-04-22 Procédé pour commander une cellule acoustique
PCT/EP2014/057685 WO2014173745A2 (fr) 2013-04-22 2014-04-16 Procédé de commande d'une cellule acoustique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP13164759.6A EP2796208A1 (fr) 2013-04-22 2013-04-22 Procédé pour commander une cellule acoustique

Publications (1)

Publication Number Publication Date
EP2796208A1 true EP2796208A1 (fr) 2014-10-29

Family

ID=48366114

Family Applications (1)

Application Number Title Priority Date Filing Date
EP13164759.6A Withdrawn EP2796208A1 (fr) 2013-04-22 2013-04-22 Procédé pour commander une cellule acoustique

Country Status (2)

Country Link
EP (1) EP2796208A1 (fr)
WO (1) WO2014173745A2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU174330U1 (ru) * 2017-04-27 2017-10-11 Федеральное государственное бюджетное образовательное учреждение высшего образования "Сибирский государственный университет геосистем и технологий" (СГУГиТ) Акустическая ловушка в поле стоячей волны на основе двух встречных пучков
CN109154516A (zh) * 2016-03-30 2019-01-04 江森自控科技公司 液体检测系统
US20220003653A1 (en) * 2018-10-30 2022-01-06 Siemens Healthcare Gmbh Isovolumetric sphering of red blood cells

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10214718B2 (en) 2013-07-01 2019-02-26 University Of Massachusetts Distributed perfusion bioreactor system for continuous culture of biological cells
CN119147476A (zh) * 2024-09-18 2024-12-17 暨南大学 一种高灵敏宽量程的气体传感系统及相关测量方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4689515A (en) * 1985-09-30 1987-08-25 Siemens Aktiengesellschaft Method for operating an ultrasonic frequency generator
EP0633049A1 (fr) 1993-05-11 1995-01-11 Trampler, Felix, Dipl. Ing. Méthode pour le traitement d'un liquide
US5711888A (en) * 1993-05-11 1998-01-27 Sonosep Biotech, Inc. Multilayered piezoelectric resonator for the separation of suspended particles
US5892315A (en) * 1996-06-26 1999-04-06 Gipson; Lamar Heath Apparatus and method for controlling an ultrasonic transducer
EP1195460A2 (fr) * 2000-09-28 2002-04-10 Kao Corporation Dispositif et procédé de nettoyage par ultrasons
US20110254519A1 (en) * 2008-12-02 2011-10-20 Hiroshi Hasegawa Ultrasonic generator and program writing method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4689515A (en) * 1985-09-30 1987-08-25 Siemens Aktiengesellschaft Method for operating an ultrasonic frequency generator
EP0633049A1 (fr) 1993-05-11 1995-01-11 Trampler, Felix, Dipl. Ing. Méthode pour le traitement d'un liquide
US5711888A (en) * 1993-05-11 1998-01-27 Sonosep Biotech, Inc. Multilayered piezoelectric resonator for the separation of suspended particles
US5892315A (en) * 1996-06-26 1999-04-06 Gipson; Lamar Heath Apparatus and method for controlling an ultrasonic transducer
EP1195460A2 (fr) * 2000-09-28 2002-04-10 Kao Corporation Dispositif et procédé de nettoyage par ultrasons
US20110254519A1 (en) * 2008-12-02 2011-10-20 Hiroshi Hasegawa Ultrasonic generator and program writing method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109154516A (zh) * 2016-03-30 2019-01-04 江森自控科技公司 液体检测系统
US11162726B2 (en) 2016-03-30 2021-11-02 Johnson Controls Technology Company Liquid detection system
RU174330U1 (ru) * 2017-04-27 2017-10-11 Федеральное государственное бюджетное образовательное учреждение высшего образования "Сибирский государственный университет геосистем и технологий" (СГУГиТ) Акустическая ловушка в поле стоячей волны на основе двух встречных пучков
US20220003653A1 (en) * 2018-10-30 2022-01-06 Siemens Healthcare Gmbh Isovolumetric sphering of red blood cells

Also Published As

Publication number Publication date
WO2014173745A2 (fr) 2014-10-30
WO2014173745A3 (fr) 2015-03-26

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