Electricity: measuring and testing – Determining nonelectric properties by measuring electric...
Reexamination Certificate
1996-06-13
2001-08-28
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Determining nonelectric properties by measuring electric...
C324S444000, C436S806000
Reexamination Certificate
active
06281670
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a two-dimensional sensor and a measurement system using the sensor for measuring cell activities. The sensor detects a potential alteration due to a cell activity.
BACKGROUND OF THE INVENTION
Medical research of nerve cells and research for the possibility of using nerve cells as electric devices are being made widely. When nerve cells become active, an action potential is generated. Ion density inside and outside of a nerve cell varies at first due to the alteration of the ion transparency, then the potential of the cell membrane alters. Therefore, it is useful to measure a two-dimensional distribution of the potential of the cell membrane for observing a sample cell or an tissue. Measuring two-dimensional distribution of the potential provides a method for determining an active part and a level of the activity.
The inventors have developed an integrated combination electrode as the two-dimensional sensor that can be used for measuring cell membrane potentials of plural spots simultaneously without insertion of glass electrodes or other stimulating electrodes into the cell (Japanese Tokukaihei 6-78889, 6-296595). This integrated combination electrode includes many micro electrodes arranged in matrix and their lead pattern formed on a glass plate using conductive substances, on which a sample cell or an tissue can be cultivated. This integrated combination electrode enables measuring potential alterations of plural spots in smaller pitch than glass electrodes or other conventional means. Furthermore, this integrated combination electrode enables long term observation of the sample cell or the tissue that are cultivated on the integrated combination electrode.
However, this integrated combination electrode is not suitable for an extensive use since it has a fixed size and a fixed pitch of measuring electrodes. In other words, it is difficult to use one integrated combination electrode for measuring different samples. In fact, different integrated combination electrodes were made by adjusting the size and pitch of electrodes to different samples.
SUMMARY OF THE INVENTION
A two-dimensional sensor and a measurement system using the sensor are described that are suitable for an extensive use of measuring cell activities of different samples, by improving the above integrated combination electrode, and making the size and the pitch of the electrodes changeable.
The two-dimensional sensor according to the present invention is a board-like sensor. The sensor has a photoconductive layer whose conductivity increases at the light-irradiated spot, an insulating layer formed on the front surface of the photoconductive layer, and an effect electrode formed on the back surface of the photoconductive layer. On the surface of the insulating layer, a cell holder is attached for holding a sample cell, culture medium, and a reference electrode. When a potential alteration occurs due to a cell activity, a signal obtained from the effect electrode substantially corresponds to a potential alteration at the spot irradiated by the light beam.
The photoconductive layer can be made of semiconductor such as selenium, CdS, Ge—Si or other intrinsic semiconductor. Alternatively, the photoconductive layer can be made of photoconductive polymer. A condensed polycyclic aromatic hydrocarbon such as anthracene, a heteroaromatic cycle such as carbazole, or an aryl-amine can be used as a photoconductive group included in side chains or principal chains of the polymer. Alternatively, an organic thin film such as vaper-deposited phthalocyanine thin film or Me-PTC (methylenperilene-carboxylic acid) that is a perilene pigment can be used.
Using the two-dimensional sensor of the present invention, and irradiating a spot of the photoconductive layer, a signal can be detected that corresponds to potential alteration of a part of the cell. This part is contacted with the spot mentioned above of the photoconductive layer. Since conductivity of the photoconductive layer increases only at the spot irradiated by the laser beam, the detected signal corresponds substantially to the potential alteration of the cell part contacted with the laser-irradiated spot of the sensor.
Therefore, the location of the laser-irradiated spot that corresponds to the measurement electrode can be changed by moving the laser beam. The size of the spot (i.e., the size of an electrode) can also be changed by focusing the laser beam. Since the insulating layer exists between the photoconductive layer and the cell, cell membrane potential itself is difficult to detect. However, an alteration of the potential, that is, an AC or pulse component of the potential can be detected. Therefore, the cell activity can be measured by the alteration of the potential.
A measurement system of the present invention comprises the two-dimensional sensor mentioned above, a laser beam source for irradiating a spot on the back surface of the two-dimensional sensor with a laser beam, a DC power source for applying a DC bias voltage between the effect electrode on the back surface of the two-dimensional sensor and the reference electrode in the cell holder on the front surface of the two-dimensional sensor, and means for processing a signal obtained between the two electrodes.
It is advantageous to use a laser beam for irradiating a spot of the sensor as a laser can be focused in a pinpoint spot easily.
It is preferable that the measurement system includes means for maintaining an environment for cultivating the sample cell in the cell holder on the sensor. The maintaining means enables long-term observation of the sample.
It is also preferable that the system further comprises means for scanning the laser beam emitted from the laser beam source, at high speed in the predetermined area of the back surface of the two-dimensional sensor. Thus cell activities in plural spots are measured substantially at the same time. Instead of scanning one laser beam, a laser array that comprises a plurality of laser elements arranged in a matrix can be used. By driving th e plurality of laser elements with a time-sharing method, faster scanning can be performed. Instead of moving the laser beam, the two-dimensional sensor can be moved so as to change the laser-irradiated spot of the sensor. In this case, the system may comprise an X-Y stage that controls the horizontal position of the two-dimensional sensor.
REFERENCES:
patent: 3448377 (1969-06-01), Seiwatz et al.
patent: 4704576 (1987-11-01), Tributsch et al.
patent: 4855243 (1989-08-01), Simic-Glavaski
patent: 0 300 651 (1989-01-01), None
patent: 06078889A (1994-03-01), None
patent: 06296595A (1994-10-01), None
Nakao et al., “Scanning-laser-beam semiconductor ph-imaging sensor”,Sensor And Actuators B, No. 2/3, Jun. 1994, Lausanne, Ch, pp. 119-123.
Iwasaki Hiroshi
Kamei Akihito
Sugihara Hirokazu
Taketani Makoto
Brown Glenn W.
Matsushita Electric - Industrial Co., Ltd.
Morrison & Foerster / LLP
LandOfFree
Two-dimensional sensor having photoconductive layer for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Two-dimensional sensor having photoconductive layer for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two-dimensional sensor having photoconductive layer for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2440134