Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3845659 A
Publication typeGrant
Publication dateNov 5, 1974
Filing dateJun 16, 1972
Priority dateJun 30, 1971
Also published asDE2231725A1, DE2231725B2, DE2231725C3
Publication numberUS 3845659 A, US 3845659A, US-A-3845659, US3845659 A, US3845659A
InventorsP Wikefeldt, E Rautio
Original AssigneeLkb Produkter Ab
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Microtome having electro-mechanical knife controlling means
US 3845659 A
Abstract
An apparatus for cutting microtome specimen sections employs electro-mechanical transducer means connected to the specimen holder, or the knife, to generate an electrical signal during the cutting which indicates the uniformity, or any variations in the uniformity of the thickness of the section.
Images(1)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent 1191 1111 3,845,659 Wikeieldt et al. 1 Nov. 5, 1974 1 1 MICROTOME HAVING 2,360,639 10 1944 Asimow et a1, 73/78 x ELECTROJVIECHANICAL KNIFE 2,465,757 3/1949 Schlesinger i. 73/133 R 2,498,881 2/1950 Eldridge 1 73/133 R CONTROLLING MEANS 2,558,563 6/1951 Janssen 73/88.5 R X [761 Inventors: Per Wikefeldt; Eskil Rautio, both 3.596.506 8/ il n 73/l33 R f Spanga S d 3,691,889 9/1972 Forsstrom 83/9155 R [73] Assignee: LKB-Pradukter AB, Bromma,

Sweden [7i]. 1 a m Primary Exammer-Charles A. Ruehl [21] Appl. No.: 263,653

[30] Foreign Application Priority Data [57] ABSTRACT June 30, 1971 Sweden 8447/71 An apparatus for cutting microtome specimen sections 73/133 73/DIG' 833 56 employs electro-mcchanical transducer means con- [58] i DIG 4' nected to the specimen holder, or the knife, to generle 0 care ate an electrical signal during the cutting which indicates the uniformity, or any variations in the uniform- [56] References Cited ity of the thickness of the section.

UNITED STATES PATENTS 2,054,787 9/1936 Beavers et a1. 73/104 X 4 Claims, 3 Drawing Figures 6 SH l l 5 H I: u1

MICROTOME HAVING ELECTRO-MECHANICAL KNIFE CONTROLLING MEANS The present invention refers to a method for indicating the thickness and its variations of sections cut in a microtome from a specimen block. The invention also refers to a method for generating variations of the thickness of a section cut from a specimen in a microtome.

When cutting ultrathin sections l.000 A) to be used for studies in an electron microscope it sometimes turns out from these studies that the sections are provided with disturbing parallel lines formed by variations of the thickness of the section. These lines might be obtained even if external vibration sources are eliminated, and the variations are thus a product of the sectioning itself. The lines, which are perpendicular to the cutting direction are usually called chatter. The distance between the lines is as a rule in the order of 5.000 A and they are thus not possible to detect in a light microscope but are discovered only when the section is studled in the electron microscope. The process of eliminating these lines, for instance by varying the angle between the knife edge and the specimen is thus very time consuming.

It is an object of the present invention to provide a method by means of which the generation of chatter could be indicated at the sectioning whereby it will be possible to carry out the necessary adjustments to eliminate the variations of thickness without studying the sections in an electron microscope. The characteristics of the method will appear from the characterizing part of claim 1.

Another problem within the ultramicrotomy consists in determining the distance between different elements in a section when studied in the electron microscope. This determination of distances within the section have hitherto generally been made by distributing small latex balls of well defined diameter over the section so as to obtain a surface scale reference. The drawback of this method consists therein that the structure of the section is often compressed in the direction of cutting and thus the surface scale reference will refer to the compressed section and no exact information will be obtained as to the original distances in the structure of the specimen. It is another object of the present invention to provide a method for performing a distance determination referring to the original specimen. The charac teristics of this method will appear from the characterizing part of claim 3.

The invention will now be explained in detail, reference being made to the enclosed drawing in which:

FIG. 1 shows an embodiment of an apparatus for carrying out the method according to the invention and FIGS. 2 and 3 illustrate'the indicating signals obtained from cutting with and without chatter respectively.

Referring now to FIG. 1 reference SH denotes the specimen arm in a microtome, the specimen being provided with a specimen block S. When cutting the specimen block, which for instance might consist of an organic specimen embedded in plastics, the specimen arm is brought downwards in the direction of the arrow towards a knife K, which cuts a section from the block. The means used for feeding the specimen arm and for handling the sections are well known per se and are not shown in FIG. I. The specimen block arm is further provided with two piezoelectrical sensors PI and P2 respectively which form part of the specimen arm. When the specimen arm at sectioning is brought downwards towards the knife, the vertical forces from the knife will then give rise to a tractive force on the lower sensor and a compressive force on the upper sensor. The sum of the tractive force on the lower sensor and the compressive force on the upper sensor will then constitute a measure of the transversal force which effects the specimen. The outputs of the electrical sensors are then connected in opposition so as to obtain a voltage between the inputs II and [2 respectively of an operational amplifier A corresponding to this force. The amplifier A is an operational amplifier having a high input impedance and a high negative internal amplification. The amplifier is further provided with a feed back path including a capacitor C connected between one output U] of the amplifier and the input II. The remaining input and output terminals 12 and U2 respectively are connected to ground.

The hitherto described apparatus works as follows, when the sensors are subject to a tractive or compressive force, a charge Q will be generated in the sensor and transferred to the capacitor C. The voltage across the capacitor will then be =Q/C and this voltage will also be obtained between the output connections UI and U2 since the feed back path of an amplifier having the above defined properties will imply that the two inputs will be kept at substantially the same potential.

The piezoelectric material of the sensors is choosen so as to make the charge Q as big as possible for a given force. The advantage of measuring the charge generated from the sensors instead of measuring the generated voltage is that the capacitor C will act as a memory element, i.e., if the sensors are subject to a constant force for a certain period of time, the output signal will be constant during this time. If the output voltages between the terminals of the sensors is measured, the measuring signal will at a constant force decrease due to leak currents. It is further possible to prove that when measuring the charge generated the sensitivity will be independent of the length and cross sectional area of the sensors. The sensors could thus be made thin and have a large cross sectional area which is essential for not effecting the elastic properties of the microtome.

In FIG. 2 there is shown to the left a section SI which has been cut in the direction of the arrow from the specimen block S in FIG. I. The thickness of the section is denoted 8. In the right of the figure there is shown the output signal V obtained from the output terminals UI and U2 during the cutting. This output signal will thus be lineary decreasing during the cutting, due to the decreasing width of the section. Experiment further indicates that the cutting force and thus the amplitude of this output signal will within certain limits be lineary related to the thickness of the section. The apparatus according to FIG. I could thus after calibration be used for determining the thickness of the sections.

In FIG. 3 there is shown to the left another section S2 cut from the specimen block, this section being provided with the parallel lines discussed above, i.e., the thickness of the section varies along the direction of cutting as indicated on the section surface. To the right in FIG. 3 there is shown the corresponding output signal from the apparatus according to FIG. I. As appears from this diagram the output signal will vary as the thickness of the section varies and one could thus detect if the section is provided with chatter. Adjustments to eliminate the chatter, for instance variation of the knife angle a could thus be made without studying the section in an electron microscope.

By using the method according to the invention one could thus by measuring the cutting forces determine the thickness of the section as well as variations of this thickness along the cutting circuit. Provisions could then be made immediately to eliminate possible defects which means that time could be saved and the risk of consuming valuable specimens without obtaining any sections useable for electron microscopy studies is eliminated.

The apparatus in FIG. 1 could also be used for generating variations of the thickness of the sections to be used for the scale reference determination as discussed above. If namely both sensors P1 and P2 are connected in series and an alternating voltage of determined frequency is supplied to the terminals 11 and 12 one will obtain variations of the thickness of the sections for instance as shown in FIG. 3. If the frequency of the alternating voltage and the vertical velocity of the arm SH are known one will obtain parallel lines having a well defined distance. Such a section could then be used as a scale reference for subsequent sections in the electron microscope. One will thus obtain an automatic compensation for the compression in the cutting direction which is normally obtained in the sections, as the distance between the lines will be compressed to a corresponding extent. The scale reference will thus be related to the specimen before cutting. It should also be noted that the method is simpler and less expensive than the scale determination using latex balls described above.

It should also be noted that the cutting force determining apparatus according to FIG. 1 also could be used for measuring such variations of the cutting forces which derive from other defects of the cutting process, e.g., due to defects in the embedding of the specimen in the specimen block.

We claim:

1. In a microtome means of the type comprising two assemblies, and means for moving one of said assemblies with respect to the other of said two assemblies, one of said assemblies including support means for a specimen to be sectioned, the other of the assemblies including support means for a knife for sectioning said specimen, one of said support means including two piezoelectric crystals, one of the crystals being mounted to absorb compressive force during said relative movement, the other of said crystals being mounted to absorb tractive force during said relative movement, electrical current integrating means and circuit means connecting said piezoelectric crystals with said integrating means in electrical opposition to each other, said integrating means generating a signal indicating the total charge generated by said crystals resulting from said relative movement while sectioning a specimen.

2. The invention defined in claim 1, wherein said support means including said piezoelectric crystals includes a specimen arm for supporting a specimen block.

3. The invention defined in claim 1, wherein said electrical current integrating means comprises amplifier means having a high negative internal amplification.

4. The invention defined in claim 3, wherein said electrical current integrating means also includes capacitor means connected between the input of said amplifier means.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2054787 *Dec 10, 1930Sep 22, 1936Western Electric CoMeasuring device
US2360639 *Oct 21, 1941Oct 17, 1944Carnegie Illinois Steel CorpMetalworking apparatus
US2465757 *Jun 17, 1946Mar 29, 1949Georg SchlesingerApparatus for testing the machineability of metals
US2498881 *Aug 2, 1947Feb 28, 1950Jones & Lamson Mach CoLoad measuring system
US2558563 *Oct 29, 1948Jun 26, 1951Gen ElectricPiezoelectric strain gauge
US3596506 *Mar 25, 1969Aug 3, 1971Atomic Energy CommissionTool force monitor
US3691889 *Apr 26, 1971Sep 19, 1972Lkb Produkter AbMicrotome feed mechanism
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4377958 *Apr 2, 1981Mar 29, 1983The United States Of America As Represented By The Secretary Of The Department Of Health And Human ServicesRemotely operated microtome
US4484503 *Jul 14, 1983Nov 27, 1984C. Reichert Optische Werke AgMicrotome having a forward-feed control system for the specimen arm and/or the knife
US4516459 *Jul 8, 1983May 14, 1985C. Reichert Optische WerkeDrive-control system for a microtome, in particular an ultramicrotome
US4532838 *Jun 17, 1983Aug 6, 1985Lkb-Produkter AbMethod in a microtome for creating the possibility that the slit between the knife edge and the specimen can be made extremely narrow
US5226335 *Apr 10, 1991Jul 13, 1993Hellmuth SitteAutomatic initial-cutting device for microtomes, particularly ultramicrotomes
US5282404 *Nov 9, 1990Feb 1, 1994The Government Of The United States Of America As Represented By The Secretary Of The Dept. Of Health & Human ServicesMicrotome with micro-plane and electric contact reference
US5609083 *Aug 15, 1990Mar 11, 1997Glass Ultra Micro Trading CompanyMethod of and an apparatus for sectioning a specimen
US7080583 *Dec 12, 2003Jul 25, 2006Leica Microsysteme GmbhMethod and apparatus for presetting specimens in a cutting device
US7677289Jul 8, 2004Mar 16, 2010President And Fellows Of Harvard CollegeMethods and apparatuses for the automated production, collection, handling, and imaging of large numbers of serial tissue sections
US8056456 *May 15, 2008Nov 15, 2011Leica Biosystems Nussloch GmbhApparatus for producing thin sections
US20040178371 *Dec 12, 2003Sep 16, 2004Leica Mikrosysteme GmbhMethod and apparatus for presetting specimens in a cutting device
US20060008790 *Jul 8, 2004Jan 12, 2006Hayworth Kenneth JMethods and apparatuses for the automated production, collection, handling, and imaging of large numbers of serial tissue sections
US20080286859 *May 15, 2008Nov 20, 2008Leica Biosystems Nussloch GmbhApparatus For Producing Thin Sections
US20100093022 *Nov 28, 2007Apr 15, 2010Kenneth HayworthMethods and apparatus for providing and processing sliced thin tissue
US20140026727 *Jun 25, 2013Jan 30, 2014Leica Biosystems Nussloch GmbhMicrotome having a piezoelectric linear actuator
WO2008066846A2 *Nov 28, 2007Jun 5, 2008President And Fellows Of Harvard CollegeMethods and apparatus for providing and processing sliced thin tissue
WO2008066846A3 *Nov 28, 2007Dec 11, 2008Harvard CollegeMethods and apparatus for providing and processing sliced thin tissue
Classifications
U.S. Classification73/862.6, 73/DIG.400, 83/915.5
International ClassificationG01L1/16, B23Q17/09, G01B7/06
Cooperative ClassificationG01B7/06, G01L1/16, Y10S73/04, B23Q17/0976
European ClassificationB23Q17/09E8B, G01L1/16, G01B7/06
Legal Events
DateCodeEventDescription
Sep 12, 1988AS02Assignment of assignor's interest
Owner name: LBK-PRODUKTER AB
Owner name: REICHERT-JUNG OPTISCHE WERKE A.G., HERNALSER HAUPT
Effective date: 19880615
Sep 12, 1988ASAssignment
Owner name: REICHERT-JUNG OPTISCHE WERKE A.G., HERNALSER HAUPT
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:LBK-PRODUKTER AB;REEL/FRAME:004943/0611
Effective date: 19880615
Owner name: REICHERT-JUNG OPTISCHE WERKE A.G.,AUSTRIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LBK-PRODUKTER AB;REEL/FRAME:4943/611
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LBK-PRODUKTER AB;REEL/FRAME:004943/0611