Abstract
The invention relates to a microcantilever, a measuring device and a method for determining mass and/or mechanical properties of a biological system.
Claims
1. Microcantilever in particular for a measuring device for determining mass and/or mechanical properties of a biological system, the cantilever has a barrier preventing migration of the biological system, characterized in that, the cantilever has a platform preventing migration of the biological system outside of the platform, where the platform is attached to a small portion of the cantilever.
2. Microcantilever according to claim 1, characterized in that, the barrier is a geometrical restriction on the cantilever.
3. Microcantilever in particular according to claim 1 or 2, characterized in that a part of the cantilever is functionalized to adhere and/or repel to a biological system.
4. Microcantilever according to claims 1 to 3, characterized in that, the platform is linked to the free end of the cantilever.
5. Microcantilever according to one of the claims 1 to 4, characterized in that, the platform is perpendicular to the cantilever beam.
6. Microcantilever according to one of the claims 1 to 5, characterized in that, the platform is parallel to the cantilever beam.
7. Microcantilever according to one of the claims 1 to 6, characterized in that, the platform is linked near or to an antinode of the cantilever.
8. Microcantilever according to one of the claims 1 to 7, characterized in that, the cantilever beam is provided with more than one platform.
9. Microcantilever according to one of the claims 1 to 7, characterized in that, it is compatible with state of the art optical microscopies.
10. Measuring device with a microcantilever according to one of the claims 1 to 9, characterized in that, it is a scanning probe microscope, atomic force microscope cytomass device, microfluidic system or a micro chamber.
11. Measuring device according to claim 10, characterized in that, the cantilever is immersed in a buffer solution.
12. Measuring device according to one of the claim 10 or 11, characterized in that, the cantilever is surrounded by a diving bell.
13. Measuring device according to one of the claims 10 to 12, characterized in that, the cantilever contains piezoelectric elements and/or resistors that can be driven to induce a cantilever oscillation.
14. Measuring device according to one of the claims 10 to 13, characterized in that, the cantilever movement can be excited by using an intensity modulated light source, magnetically, electrically, thermally and/or mechanically in use.
15. Measuring device according to one of the claims 10 to 14, characterized in that, the cantilever contains piezoresistors and/or piezoelectric elements capable for detecting cantilever deflection.
16. Measuring device according to one of the claims 10 to 15, characterized in that, the cantilever movement is read out by an optical beam deflection scheme or a Doppler interferometer.
17. Method for determining mass and/or mechanical properties of a biological system with a micro cantilever according to one of the claims 1 to 9 and/or a measuring device according to one of the claims 10 to 16.
18. Method according to claim 17, characterized in that, the cantilever is excited with one or more vibrational modes.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The invention will be described in more detail herein after with reference to exemplary embodiments. In the drawings,
(2) FIG. 1 show a) and b) scanning electron microscopy (SEM) images showing perspective and side views of a position insensitive L-shaped microcantilever, c) schematic drawing of a L-shaped microcantilever and d) an optical microscopy top view of the L-shaped microcantilever and a cell attached to it;
(3) FIG. 2 shows schematic drawings of possible cantilever geometries using a platform as a barrier to cell migration;
(4) FIG. 3 shows a schematic drawings of possible cantilever geometries using a geometrical structure as a barrier to cell migration;
(5) FIG. 4 shows a block diagram of the setup of the measuring device;
(6) FIG. 5 shows a schematic drawing of a platform linked to a cantilever;
(7) FIG. 6 shows a schematic drawings of two platforms linked to a cantilever.
DETAILED DESCRIPTION OF THE EMBODIMENTS
(8) FIG. 1 shows a position insensitive L-shaped microcantilever 1 in various images FIGS. 1a, 1b and 1d, and a schematic drawing of the cantilever in FIG. 1c.
(9) FIG. 1a shows a scanning electron microscopy (SEM) image of a perspective of a L-shaped microcantilever and FIG. 1b shows a side view of a L-shaped microcantilever, sculpted with a focused ion beam (FIB). FIG. 1d depicts an optical microscopy image showing the top view of the L-shaped cantilever of FIGS. 1a and 1b. In FIG. 1d a cell 3 attached to the cantilever 1.
(10) In FIG. 1c a schematic picture of a cell 3 attached to a plate 2 of the L-shaped microcantilever 1 is shown. The cantilever 1 is moved laterally towards the cell 3 in order to attach the cell 3 to the functionalized plate 2. After this, the cantilever 1 is withdrawn from the surface of the Petri dish to measure the mass of the cell 3 over time.
(11) FIG. 2a shows a cantilever 11 with a platform 12 attached at the free end of the cantilever 11, perpendicular to the cantilever beam 14. A cell 13 is attached to the platform 12. The platform 12 is linked to the of the cantilever 11. The whole platform 12 is moving essentially with the same oscillation amplitude as the cantilever 11. Therefore, the mass of the cell 13 attached on the platform 12 can be accurately determined.
(12) The platform defines a T shaped cantilever in FIG. 2a, 2b. In FIGS. 2c-2f the platform 12 defines a L shaped cantilever. This means that the perpendicular platform can be attached at one side or at the middle to the cantilever beam.
(13) In FIG. 2b cantilever of FIG. 2a is equipped with a diving bell 15. The cantilever 11 body can thus be partially kept out of a buffer solution, for example, which increases the quality factor of the cantilever 11 and therefore the mass sensitivity.
(14) FIG. 2c shows a triangular cantilever 21 with a platform 22 at the free end of the cantilever 21 parallel to the cantilever beam 24. A cell 23 is attached to the platform 22.
(15) FIG. 2d shows a cantilever where the platform 32 is in the plane of the cantilever beam 34 and connected to the beam via a small connector 35. A cell 33 is attached to the platform 32.
(16) In FIG. 2e the platform 42 is attached with a distance to the free end of the cantilever 41, perpendicular to the cantilever beam 44. A cell 43 is attached to the platform 42.
(17) FIG. 2f shows a cantilever 51 with a platform 52 attached with a distance to the free end of the cantilever 51, parallel to the cantilever beam 54 via a connector 56. A cell 53 is attached to the platform 52.
(18) In FIGS. 2a-2f the cell 13, 23, 33, 43, 53 is prevented from migrating outside the platform by the edges of the respective platform 12, 22, 32, 42, 52. The platform 12, 22, 32, 42, 52 oscillates with a certain amplitude. The cell 13, 23, 33, 43, 53 attached to the platform 12, 22, 32, 42, 52 can freely move on the platform 12, 22, 32, 42, 52 while the mass sensitivity of the cantilever remains constant. The platform 12, 22, 32, 42, 52 is linked to a small portion of the cantilever. In addition physical or chemical modifications, like edges of the platform 12, 22, 32, 42, 52 or coatings can be used, so that the cell 13, 23, 33, 43, 53 is confined to stay within the platform 12, 22, 32, 42, 52, being very unlikely that a mammalian cells, for example, moves out from the platform 12, 22, 32, 42, 52.
(19) FIG. 3a shows a three-dimensional picture of a cantilever, while FIGS. 3b to 3d show top views of different cantilever geometries.
(20) The cantilever 61 in FIGS. 3a and 3b is divided in two pieces 64 and 62 by gap 65. The cell 63 kept in the piece 62 close to the front end of the cantilever 61.
(21) FIG. 3c shows a cantilever 71 where the platform 72 is in the plane of the cantilever beam 74 and connected to the beam 74 via a small connector 75. Here the connector 75 is also in line to the cantilever beam 74. A cell 73 is attached to the platform 72.
(22) FIG. 3d shows a triangular cantilever 81 with a platform 82 at the free end of the cantilever 81. A cell 83 is attached to the platform 82. Through the triangular shape with the two legs 84 and 85 a migration of the cell 83 along the cantilever beam is also hindered.
(23) FIGS. 3a to 3d the cell 63, 73, 83 is prevented from migrating along the cantilever 61, 71, 81 by the gap 65, the connector 75 or the triangular shape with two legs 84, 85. The cantilever 61, 71, 81 oscillates with a certain amplitude. The cell 63, 73, 83 is attached to the piece 62, the platform 72, 82. The cell 63, 73, 83 stays within the piece 62 or the platform 72, 82 while the mass sensitivity of the cantilever remains largely constant. Physical or chemical modifications or coatings can be additionally used, to enhance the confinement of the cell 63, 73, 83 within the platform 72, 82 or piece 62.
(24) FIG. 4 shows a setup of a measuring device (or picobalance) as a block diagram. The intensity modulated blue laser excites an oscillatory movement of the microcantilever, which is detected by an infrared laser (red) reflected from the free cantilever end onto a four-quadrant photodiode. Also a near infrared laser can be used for excitation and a visible red laser. In fact different wavelengths can be used with different advantages and disadvantages as know to the person skilled in the art, as e.g. fluorescence may be limited in wavelength. To measure the amplitude and phase of the cantilever movement the signal from the photodiode is analyzed by a lock-in amplifier. For high time resolution measurements, a phase-locked loop instantaneously tracks the natural resonance frequency of the cantilever.
(25) FIG. 5 shows a cantilever 91 where the platform 92 is parallel to the cantilever beam 94 at rest and connected to the beam 94 via a small connector 95. The platform 92 is attached with a distance to the free end of the cantilever 91, parallel to the cantilever beam 94. A cell 93 is attached to the platform 52.
(26) For illustration purposes the cantilever beam 94 is shown oscillating at a higher flexural mode than the fundamental one. The antinode 96 of the cantilever beam 94 is shown in FIG. 5.
(27) The platform 92 is linked to the antinode 96 of the cantilever beam 94. In other examples the platform 92 is linked near an antinode of the cantilever beam. Antinodes provide the highest oscillation amplitude for a certain eigenmode and therefore provide the highest mass sensitivity of the cantilever beam 94. The whole platform 92 moves with the amplitude of the antinode 96.
(28) The number and location of antinodes 96 depends on the vibration eigenmode of the cantilever 91 and its geometry. The cantilever 91 can be oscillated with several eigenmodes simultaneously.
(29) A cantilever can have more than one platform, as shown in FIGS. 6a and 6b.
(30) FIG. 6a shows a cantilever 101 with two platforms 102-1, 102-2 and FIG. 6b also shows a cantilever 111 with two platforms 112-1, 112-2. In FIG. 6a each platform 102-1, 102-2 is linked to or near an antinode 106, 107. In FIG. 6b each platform 112-1, 112-2 is linked to or near an antinode 116, 117.
(31) For illustration purposes the cantilever beam 104, 114 is shown oscillating at a higher eigenmode than the fundamental one. The antinodes 106, 107 of the cantilever beam 104 are shown in FIG. 6a. FIG. 6b shows the antinodes 116, 117 of the cantilever beam 114. FIGS. 6a and 6b show a cantilever oscillating at a certain eigenmode. However, oscillating at several eigenmodes simultaneously is possible, however it is not shown for simplicity.
(32) In the examples shown in FIG. 6a, 6b, the cantilever beam 104, 114 has one platform 102-1, 112-1 located at antinode 106, 116 and another platform 102-2, 112-2 located at antinode 107, 117 of the cantilever 101, 111. The platforms 102-1, 102-2 have the same orientation relative to the cantilever beam 104. Both are arranged at the same side of the cantilever beam 104. The platforms 112-1, 112-2 are arranged on different sides of the cantilever beam 114. Platforms 102-1, 102-2 of FIG. 6a and platforms 112-1, 112-2 of FIG. 6b are parallel to the cantilever beam 104 at rest (no oscillation), 114. In other examples the platforms may have any orientation relative to the cantilever, as shown in FIG. 2 or 3, for example.
(33) It has to be noted that the described methods, apparatuses and systems can be used alone or as combination with the methods, apparatuses and systems described in this document. Furthermore, any of the aspects relating to the methods, apparatuses and systems described in this document can be combined. In addition to any combination of features belonging to one type of subject-matter also any combination between features relating to different subject matters is considered to be disclosed with this application. All features can be combined providing synergetic effects that are more than the simple summation of the features.
(34) The invention has been described in detail in the drawings and foregoing description. However, the invention can be performed in many different embodiments and should not be limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing a claimed invention, from a study of the drawings, the disclosure, and the dependent claims.
(35) In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. The terminology used in the description and claims should not be construed as limiting the scope of the invention. Any reference signs in the claims should not be construed as limiting the scope. In the drawings same reference signs refer to same elements.
