Method of forming detection spots on an analyte detection chip

When a large number of detection spots are to be formed on analyte detection chips such as DNA chips or DNA microarrays, spot-forming liquid containing a component for formation of detection spots is spotted simultaneously to the surfaces of a plurality of slide glasses or to a plurality of regions on a single slide glass to thereby improve the fabrication efficiency of detection chips and provide the detection chips inexpensively. A plurality of injection modules 10 a, 30 a, and 40 a are employed as a means for forming detection spots on slide glasses. Each injection module is equipped with injection units 10 d adapted to jet spot-forming liquid containing a component for formation of the detection spots. The spot-forming liquid is jetted simultaneously from the injection units 10 a, 30 a, and 40 a of the respective injection modules toward the surfaces of the plurality of slide glasses 20 corresponding to the injection modules, or a plurality of regions on the single slide glass 20, in order to simultaneously form detection spots on the surfaces of the plurality of slide glasses, or in the regions on the single slide glass. Thus, the efficiency in formation of detection spots is improved.

EMBODIMENTS OF THE INVENTION The present invention relates to a method of forming detection spots on an analyte detection chip. FIGS. 1 to 6 show a forming method according to a first embodiment adapted to form detection spots on a DNA chip or DNA microarray, which serves as a detection chip. FIG. 1 shows a positional relationship between an injection apparatus 10 used in the forming method and adapted to dispense a spot-forming liquid, and slide glasses 20 (indicated by two-dot chain lines and denoted by 20 a to 20 d ), which are used as supports. The injection apparatus 10 is an experimental apparatus for experimentally carrying out the detection-spot forming method according to the present invention and includes four injection modules 10 a ( 10 a 1 to 10 a 4 ). However, a practical apparatus may include several to several tens of injection modules 10 a. The four injection modules 10 a of the injection apparatus 10 are disposed on a support table 10 b . The injection apparatus 10 includes a drive unit 10 c for intermittently moving the support table 10 b within a horizontal plane along a front/back direction and a left/right direction (the directions of arrows shown in FIG. 1 ). Accordingly, all the injection modules 10 a can be intermittently moved, together with the support table 10 b, within a horizontal plane along the front/back and left/right directions. Meanwhile, the number of slide glasses 20 on which detection spots are to be formed is set to four in order to match the number of the injection modules 10 a. That is, four slide glasses 20 a, 20 b, 20 c, and 20 d are disposed below the injection apparatus 10 such that the slide glasses 20 a, 20 b, 20 c, and 20 d face the respective injection modules 10 a with a predetermined vertical gap formed therebetween. Notably, in the following description in relation to the injection modules 10 a ( 10 a 1 to 10 a 4 ), the injection modules are denoted by 10 a 1 to 10 a 4 when they must be distinguished from each other, and the injection modules are denoted collectively by 10 a when they need not be distinguished from each other. A similar rule is applied to the slide glasses 20 ( 20 a, 20 b, 20 c, and 20 d ). As shown in FIG. 2 , each injection module 10 a of the injection apparatus 10 is provided with 16 injection units 10 d arranged in an 8×2 array. Each injection unit 10 d is configured as shown in FIG. 3 . The injection unit 10 d includes a substrate 11 having a cavity for accommodating a spot-forming liquid, and drive means 12 . In the present embodiment, a micro-pipet proposed in Japanese Patent Application No. 11-301626, which is a previous application of the present applicant, is used as the injection unit 10 d. The substrate 11 of the injection unit 10 d is formed through a process of sintering a laminate of green sheets of zirconia ceramics in such a manner that the substrate 11 includes a closure plate 11 a, a spacer plate 11 b, and a nozzle plate 11 c, which cooperate to form a cavity 13 therein. A spot-forming liquid charge inlet 13 a communicates with the cavity 13 via a communication passage 17 and an introduction opening 15 . Further, a discharge port (injection nozzle) 16 communicates with the cavity 13 . The drive means 12 is composed of a piezoelectric/electrostrictive element, which includes an intermediate piezoelectric/electrostrictive layer 12 a, and upper and lower electrodes 12 b and 12 c, which sandwich the piezoelectric/electrostrictive layer 12 a. The drive means 12 is bonded to the closure plate 11 a of the substrate 11 in such a manner that the lower electrode 12 c faces the top surface of the closure plate 11 a. The drive means 12 operates upon application of voltage to the electrodes 12 b and 12 c. Specifically, upon application of voltage to the electrodes 12 b and 12 c, the piezoelectric/electrostrictive layer 12 a deforms so as to reduce the volume of the cavity 13 . As a result of a reduction in the volume of the cavity 13 , a predetermined amount of the spot-forming liquid is discharged from the cavity 13 via the discharge port 16 at a predetermined rate. A spot-forming liquid containing DNA fragments is accommodated in the cavity 13 of the injection unit 10 d, and the spot-forming liquid is intermittently discharged a predetermined amount at a time, whereby minute detection spots of a DNA chip or DNA microarray are formed on the slide glasses 20 . Although the size of the cavity 13 is determined in consideration of the size of detection spots to be formed, the cavity 13 has a length of 1 mm to 5 mm, a width of 0.1 mm to 1 mm, and a thickness of 0.1 mm to 0.5 mm. The spot-forming liquid containing DNA fragments is prepared through a process of dispersing DNA fragments having a length of about 1 to 10,000 base pairs into a buffer solution (pH 7.0) containing sodium chloride (0.45 M) and sodium citrate (0.045 M) in such a manner that the concentration of the DNA fragments becomes 0.3 &mgr;g/&mgr;l. Use of the injection unit 10 d enables the spot-forming liquid to be jetted in the form of droplets having a diameter of slightly greater than 100 &mgr;m, at a pitch of several hundreds &mgr;m. The injection units 10 d are arranged in a regular pattern on a module base 14 in order to form the injection module 10 a. Detection spots are formed on the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d in the following manner by use of the injection apparatus 10 . The drive unit 10 c is operated to intermittently move the support table 10 b in a horizontal plane along the front/back direction and/or the left/right direction in such a manner that the injection modules 10 a 1 to 10 a 4 disposed on the support table 10 b are caused to successively face predetermined regions of the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d, which are disposed below the injection apparatus 10 ; and all the injection units 10 d of the respective injection modules 10 a 1 to 10 a 4 are caused to simultaneously jet spot-forming liquids toward the predetermined regions of the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d. Thus, detection spots which are equal in number to the injection units 10 d are formed in the regions. FIG. 4 shows the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d in the midst of an operation for forming detection spots. FIG. 5 shows portions of the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d in an enlarged manner. In FIG. 4 , black-colored regions a 1 , b 1 , c 1 , and d 1 represent regions in which the injection modules 10 a 1 to 10 a 4 form detection spots simultaneously during a first spotting operation. In the black-colored regions a 1 , b 1 , c 1 , and d 1 of the slide glasses 20 a, 20 b, 20 c, and 20 d, all the injection units 10 d of the injection modules 10 a 1 to 10 a 4 jet spot-forming liquids simultaneously in order to form detection spots simultaneously. The number of simultaneously formed detection spots corresponds to the number of the injection units 10 d provided in the injection modules 10 a 1 to 10 a 4 . When the above-described injection apparatus 10 is used, as shown in FIG. 6, 16 detection spots are formed in an 8×2 array in each of the black-colored regions a 1 , b 1 , c 1 , and d 1 . The detection spots thus formed all differ from one another in terms of components contained therein. After completion of the first spotting operation, the injection apparatus 10 is moved in the direction of arrow y 1 shown in FIG. 4 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection modules 10 a 1 and 10 a 4 above the surfaces of the slide glasses 20 b and 20 c. Subsequently, a second spotting operation is performed in the same manner as in the first spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 1 toward a spot region a 2 of the slide glass 20 b shown in FIG. 5 , whereby the same detection spots as those formed in the spot region a 1 are formed in the spot region a 2 . Similarly, spot-forming liquid is jetted from the injection module 10 a 4 toward a spot region d 2 of the slide glass 20 c shown in FIG. 5 , whereby the same detection spots as those formed in the spot region d 1 are formed in the spot region d 2 . After completion of the second spotting operation, the injection apparatus 10 is moved in the direction of arrow y 1 shown in FIG. 4 by an amount corresponding to the length of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection module 10 a 1 above the surface of the slide glass 20 c. Subsequently, a third spotting operation is performed in the same manner as in the second spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 1 toward a spot region a 3 of the slide glass 20 c shown in FIG. 5 , whereby the same detection spots as those formed in the spot region a 1 are formed in the spot region a 3 . After completion of the third spotting operation, the injection apparatus 10 is moved in the direction of arrow x 2 shown in FIG. 4 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection modules 10 a 2 and 10 a 1 above the surfaces of the slide glasses 20 c and 20 d. Subsequently, a fourth spotting operation is performed in the same manner as in the third spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 2 toward a spot region b 4 of the slide glass 20 c shown in FIG. 5 , whereby the same detection spots as those formed in the spot region b 1 are formed in the spot region b 4 . Similarly, spot-forming liquid is jetted from the injection module 10 a 1 toward a spot region a 4 of the slide glass 20 d shown in FIG. 5 , whereby the same detection spots as those formed in the spot region a 1 are formed in the spot region a 4 . After completion of the fourth spotting operation, the injection apparatus 10 is moved in the direction of arrow x 3 shown in FIG. 4 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection module 10 a 2 above the surface of the slide glass 20 d. Subsequently, a fifth spotting operation is performed in the same manner as in the fourth spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 2 toward a spot region b 5 of the slide glass 20 d shown in FIG. 5 , whereby the same detection spots as those formed in the spot region b 1 are formed in the spot region b 5 . After completion of the fifth spotting operation, the injection apparatus 10 is moved in the direction of arrow y 2 shown in FIG. 4 by an amount corresponding to the length of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection modules 10 a 2 and 10 a 3 above the surfaces of the slide glasses 20 a and 20 d. Subsequently, a sixth spotting operation is performed in the same manner as in the fifth spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 2 toward a spot region b 6 of the slide glass 20 a shown in FIG. 5 , whereby the same detection spots as those formed in the spot region b 1 are formed in the spot region b 6 . Similarly, spot-forming liquid is jetted from the injection module 10 a 3 toward a spot region c 6 of the slide glass 20 d shown in FIG. 5 , whereby the same detection spots as those formed in the spot region c 1 are formed in the spot region c 6 . After completion of the sixth spotting operation, the injection apparatus 10 is moved in the direction of arrow y 3 shown in FIG. 4 by an amount corresponding to the length of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection module 10 a 3 above the surface of the slide glass 20 a. Subsequently, a seventh spotting operation is performed in the same manner as in the sixth spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 3 toward a spot region c 7 of the slide glass 20 a shown in FIG. 5 , whereby the same detection spots as those formed in the spot region c 1 are formed in the spot region c 7 . After completion of the seventh spotting operation, the injection apparatus 10 is moved in the direction of arrow x 4 shown in FIG. 4 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection modules 10 a 3 and 10 a 4 above the surfaces of the slide glasses 20 b and 20 a. Subsequently, an eighth spotting operation is performed in the same manner as in the seventh spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 4 toward a spot region d 8 of the slide glass 20 a shown in FIG. 5 , whereby the same detection spots as those formed in the spot region d 1 are formed in the spot region d 8 . Similarly, spot-forming liquid is jetted from the injection module 10 a 3 toward a spot region c 8 of the slide glass 20 b shown in FIG. 5 , whereby the same detection spots as those formed in the spot region c 1 are formed in the spot region c 8 . After completion of the eighth spotting operation, the injection apparatus 10 is moved in the direction of arrow x 1 shown in FIG. 4 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection module 10 a 4 above the surface of the slide glass 20 b. Subsequently, a ninth spotting operation is performed in the same manner as in the eighth spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 4 toward a spot region d 9 of the slide glass 20 b shown in FIG. 5 , whereby the same detection spots as those formed in the spot region d 1 are formed in the spot region d 9 . The injection apparatus 10 completes a first injection cycle through performance of the above-described nine spotting operations. Subsequently, the injection units 10 d are cleaned and then filled with corresponding spot-forming liquids to thereby prepare for a second injection cycle. After completion of the preparation, the injection apparatus 10 resumes the operation in order to perform spotting operations in the same sequence as in the first injection cycle for a group of spot regions adjacent to the above-described group of spot regions. In the detection-spot forming method of the present embodiment, through repetition of the above-described injection cycle, a predetermined number of detection spots are formed on the surface of each of the slide glasses 20 a, 20 b, 20 c, and 20 d in order to simultaneously fabricate-DNA chips or DNA microarrays equal in number to the slide glasses 20 a, 20 b, 20 c, and 20 d. FIG. 7 shows a detection-spot forming method according to a second embodiment of the present invention; in particular, a positional relationship between an injection apparatus 30 used in the forming method and adapted to dispense a spot-forming liquid, and slide glasses 20 (indicated by two-dot chain lines and denoted by 20 a to 20 d ), which are used as supports. The injection apparatus 30 is an experimental apparatus for experimentally carrying out the detection-spot forming method according to the present invention and includes four injection modules 30 a ( 30 a 1 to 30 a 4 ). However, a practical apparatus may include several to several tens of injection modules 30 a. The four injection modules 30 a of the injection apparatus 30 are disposed on a support table 30 b. The injection apparatus 30 includes a drive unit 30 c for intermittently moving the support table 30 b within a horizontal plane along a front/back direction and a left/right direction (the directions of arrows shown in FIG. 7 ). Accordingly, all the injection modules 30 a can be moved, together with the support table 30 b, within a horizontal plane along the front/back and left/right directions. Meanwhile, the number of slide glasses 20 on which detection spots are to be formed is set to four in order to match the number of the injection modules 30 a. That is, four slide glasses 20 a, 20 b, 20 c, and 20 d are disposed below the injection apparatus 30 such that the slide glasses 20 a, 20 b, 20 c, and 20 d face the respective injection modules 30 a with a predetermined vertical gap formed therebetween. Notably, in the following description in relation to the injection modules 30 a ( 30 a 1 to 30 a 4 ), the injection modules are denoted by 30 a 1 to 30 a 4 when they must be distinguished from each other, and the injection modules are denoted collectively by 30 a when they need not be distinguished from each other. A similar rule is applied to the slide glasses 20 ( 20 a, 20 b, 20 c, and 20 d ). As shown in FIG. 8 , each injection module 30 a of the injection apparatus 30 is provided with 16 injection units 30 d arranged in an 8×2 array. Each injection unit 30 d has the same configuration as the injection unit 10 d shown in FIG. 3 and holds a spot-forming liquid containing DNA fragments and the same components as described above. Detection spots are formed on the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d in the following manner by use of the injection apparatus 30 . The drive unit 30 c is operated to intermittently move the support table 30 b in a horizontal plane along the front/back direction and/or the left/right direction in such a manner that the injection modules 30 a 1 to 30 a 4 disposed on the support table 30 b are caused to successively face predetermined regions of the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d, which are disposed below the injection apparatus 30 ; and all the injection units 30 d of the respective injection modules 30 a 1 to 30 a 4 are caused to simultaneously jet spot-forming liquids toward the predetermined regions of the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d. Thus, detection spots which are equal in number to the injection units 30 d are formed in the regions. FIG. 9 shows the surfaces of the four slide glasses 20 a, 20 b, 20 c, and 20 d in the midst of an operation for forming detection spots, as well as the respective injection modules 30 a 1 to 30 a 4 . In FIG. 9, a “&plus;” mark indicates each of detection-spot forming positions on the slide glasses 20 a, 20 b, 20 c, and 20 d serving as supports; and a “o” mark indicates each of the discharge ports of the injection units 30 d of the injection modules 30 a 1 to 30 a 4 . In FIG. 9 , black-colored regions a 1 , b 1 , c 1 , and d 1 represent respective regions in which single injection units 30 d (located at the upper right corners of the injection modules in FIG. 9 ), among the 16 injection units 30 d for each of the injection modules 30 a 1 to 30 a 4 , form a detection spot simultaneously during a first spotting operation. In the spot forming method according to the present embodiment, all the injection units 30 d of the respective injection modules 30 a 1 to 30 a 4 simultaneously jet spot-forming liquids toward detection-spot forming positions on the slide glasses 20 a, 20 b, 20 c, and 20 d, which positions correspond to the injection units 30 d indicated by “o” marks, to thereby form detection spots. The detection spots thus formed all differ from one another in terms of components contained therein. The positions of the injection units 30 d of the injection modules 30 a 1 to 30 a 4 , which face the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d, are determined such that the distances between the corresponding injection units 30 d of the injection modules 30 a 1 to 30 a 4 become an integral multiple of the intervals of the detection spots. Specifically, as shown in FIG. 9 , the positional relationship among the injection modules 30 a 1 to 30 a 4 is set in such a manner that the distance dx between the injection modules 30 a 1 and 30 a 2 along the x 1 direction is greater than the distance Dx between the slide glasses 20 a and 20 b along the x 1 direction by an amount corresponding to the one interval of the detection spots; and that the distance dy between the injection modules 30 a 1 and 30 a 4 along the y 1 direction is greater than the distance Dy between the slide glasses 20 a and 20 d along the y 1 direction, by an amount corresponding to the one interval of the detection spots. FIG. 10 shows portions of the surfaces of the slide glasses 20 a, 20 b, 20 c, and 20 d; in particular, regions in which the injection units 30 d located at the upper right corners of the injection modules in FIG. 9 , among the 16 injection units 30 d of each of the injection modules 30 a 1 to 30 a 4 , form a detection spot simultaneously during the first spotting operation. After completion of the first spotting operation, the injection apparatus 30 is moved in the direction of arrow x 1 shown in FIG. 9 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection modules 30 a 1 and 30 a 4 above the surfaces of the slide glasses 20 b and 20 c. Subsequently, a second spotting operation is performed in the same manner as in the first spotting operation. As a result, spot-forming liquid is jetted from the injection module 30 a 1 toward a spot region a 2 of the slide glass 20 b shown in FIG. 10 , whereby the same detection spots as those formed in the spot regional are formed in the spot region a 2 . Similarly, spot-forming liquid is jetted from the injection module 30 a 4 toward a spot region d 2 of the slide glass 20 c shown in FIG. 10 , whereby the same detection spots as those formed in the spot region d 1 are formed in the spot region d 2 . After completion of the second spotting operation, the injection apparatus 30 is moved in the direction of arrow y 1 shown in FIG. 9 by an amount corresponding to the length of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection module 30 a 1 above the surface of the slide glass 20 c. Subsequently, a third spotting operation is performed in the same manner as in the second spotting operation. As a result, spot-forming liquid is jetted from the injection module 30 a 1 toward a spot region a 3 of the slide glass 20 c shown in FIG. 10 , whereby the same detection spots as those formed in the spot region a 1 are formed in the spot region a 3 . After completion of the third spotting operation, the injection apparatus 30 is moved in the direction of arrow x 2 shown in FIG. 9 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection modules 30 a 2 and 30 a 1 above the surfaces of the slide glasses 20 c and 20 d. Subsequently, a fourth spotting operation is performed in the same manner as in the third spotting operation. As a result, spot-forming liquid is jetted from the injection module 30 a 2 toward a spot region b 4 of the slide glass 20 c shown in FIG. 10 , whereby the same detection spots as those formed in the spot region blare formed in the spot region b 4 . Similarly, spot-forming liquid is jetted from the injection module 30 a 1 toward a spot region a 4 of the slide glass 20 d shown in FIG. 10 , whereby the same detection spots as those formed in the spot region a 1 are formed in the spot region a 4 . After completion of the fourth spotting operation, the injection apparatus 30 is moved in the direction of arrow x 3 shown in FIG. 9 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection module 30 a 2 above the surface of the slide glass 20 d. Subsequently, a fifth spotting operation is performed in the same manner as in the fourth-spotting operation. As a result, spot-forming liquid is jetted from the injection module 10 a 2 toward a spot region b 5 of the slide glass 20 d shown in FIG. 10 , whereby the same detection spots as those formed in the spot region b 1 are formed in the spot region b 5 . After completion of the fifth spotting operation, the injection apparatus 30 is moved in the direction of arrow y 2 shown in FIG. 9 by an amount corresponding to the length of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection modules 30 a 2 and 30 a 3 above the surfaces of the slide glasses 20 a and 20 d. Subsequently, a sixth spotting operation is performed in the same manner as in the fifth spotting operation. As a result, spot-forming liquid is jetted from the injection module 30 a 2 toward a spot region b 6 of the slide glass 20 a shown in FIG. 10 , whereby the same detection spots as those formed in the spot region b 1 are formed in the spot region b 6 . Similarly, spot-forming liquid is jetted from the injection module 30 a 3 toward a spot region c 6 of the slide glass 20 d shown in FIG. 10 , whereby the same detection spots as those formed in the spot region c 1 are formed in the spot region c 6 . After completion of the sixth spotting operation, the injection apparatus 30 is moved in the direction of arrow y 3 shown in FIG. 9 by an amount corresponding to the length of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection module 30 a 3 above the surface of the slide glass 20 a. Subsequently, a seventh spotting operation is performed in the same manner as in the sixth spotting operation. As a result, spot-forming liquid is jetted from the injection module 30 a 3 toward a spot region c 7 of the slide glass 20 a shown in FIG. 10 , whereby the same detection spots as those formed in the spot region c 1 are formed in the spot region c 7 . After completion of the seventh spotting operation, the injection apparatus 30 is moved in the direction of arrow x 4 shown in FIG. 9 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection modules 30 a 3 and 30 a 4 above the surfaces of the slide glasses 20 b and 20 a. Subsequently, an eighth spotting operation is performed in the same manner as in the seventh spotting operation. As a result, spot-forming liquid is jetted from the injection module 30 a 4 toward a spot region d 8 of the slide glass 20 a shown in FIG. 10 , whereby the same detection spots as those formed in the spot region d 1 are formed in the spot region d 8 . Similarly, spot-forming liquid is jetted from the injection module 30 a 3 toward a spot region c 8 of the slide glass 20 b shown in FIG. 10 , whereby the same detection spots as those formed in the spot region c 1 are formed in the spot region c 8 . After completion of the eighth spotting operation, the injection apparatus 30 is moved in the direction of arrow x 1 shown in FIG. 9 by an amount corresponding to the width of the slide glasses 20 a, 20 b, 20 c, and 20 d, in order to position the injection module 30 a 4 above the surface of the slide glass 20 b. Subsequently, a ninth spotting operation is performed in the same manner as in the eighth spotting operation. As a result, spot-forming liquid is jetted from the injection module 30 a 4 toward a spot region d 9 of the slide glass 20 b shown in FIG. 10 , whereby the same detection spots as those formed in the spot region d 1 are formed in the spot region d 9 . The injection apparatus 30 completes a first injection cycle through performance of the above-described nine spotting operations. Subsequently, the injection units 30 d are cleaned and then filled with corresponding spot-forming liquids to thereby prepare for a second injection cycle. After completion of the preparation, the injection apparatus 30 resumes the operation in order to perform spotting operations in the same sequence as in the first injection cycle for a group of spot regions adjacent to the above-described group of spot regions. In the detection-spot forming method of the present embodiment, through repetition of the above-described injection cycle, a predetermined number of detection spots are formed on the surface of each of the slide glasses 20 a, 20 b, 20 c, and 20 d in order to simultaneously fabricate DNA chips or DNA microarrays equal in number to the slide glasses 20 a, 20 b, 20 c, and 20 d. FIG. 11 shows a detection-spot forming method according to a third embodiment of the present invention; in particular, a positional relationship between an injection apparatus 40 used in the forming method and a slide glass 20 (indicated by a two-dot chain line), which is used as a support. The injection apparatus 40 is an experimental apparatus for experimentally carrying out the detection-spot forming method according to the present invention and includes four injection modules 40 a ( 40 a 1 to 40 a 4 ) However, a practical apparatus may include several to several tens of injection modules 40 a. The four injection modules 40 a of the injection apparatus 40 are disposed on a support table 40 b. The injection apparatus 40 includes a drive unit 40 c for intermittently moving the support table 40 b within a horizontal plane along a front/back direction and a left/right direction (the directions of arrows shown in FIG. 11 ). Accordingly, all the injection modules 40 a can be moved, together with the support table 40 b, within a horizontal plane along the front/back and left/right directions. Meanwhile, the slide glass 20 on which detection spots are to be formed is a single piece and has a size to face all the injection modules 40 a of the injection apparatus 40 . That is, the slide glass 20 is disposed below the injection apparatus 40 such that the slide glass 20 faces the injection modules 40 a with a predetermined vertical gap formed therebetween. In the injection apparatus 40 , each injection module 40 a has a single injection unit 40 d. Each injection unit 40 d has the same configuration as the injection unit 10 d shown in FIG. 3 and holds a spot-forming liquid containing DNA fragments and the same components as described above. Notably, in the following description in relation to the injection modules 40 a ( 40 a 1 to 40 a 4 ), the injection modules are denoted by 40 a 1 to 40 a 4 when they must be distinguished from each other, and the injection modules are denoted collectively by 40 a when they need not be distinguished from each other. Detection spots are formed on the surface of the slide glass 20 in the following manner by use of the injection apparatus 40 . The drive unit 40 c is operated to intermittently move the support table 40 b in a horizontal plane along the front/back direction and/or the left/right direction in such a manner that the injection modules 40 a 1 to 40 a 4 disposed on the support table 40 b are caused to successively face predetermined regions of the surface of the slide glass 20 , which is disposed below the injection apparatus 40 ; and all the injection units 40 d of the respective injection modules 40 a 1 to 40 a 4 are caused to simultaneously jet spot-forming liquids toward the predetermined regions of the surface of the slide glass 20 . Thus, detection spots which are equal in number to the injection units 40 d are formed in the regions. FIG. 12 shows the surface of the slide glass 20 in the midst of an operation for forming detection spots. In FIG. 12 , black-colored regions a 1 , b 1 , c 1 , and d 1 represent regions in which the injection modules 40 a 1 to 40 a 4 form detection spots simultaneously during a first spotting operation. In the black-colored regions a 1 , b 1 , c 1 , and d 1 of the slide glass 20 , all the injection units 40 d of injection modules 40 a 1 to 40 a 4 simultaneously jet spot-forming liquids in order to form detection spots simultaneously. The number of simultaneously formed detection spots corresponds to the number of the injection units 40 d of the injection modules 40 a 1 to 40 a 4 . In the injection apparatus 40 , as shown in FIG. 13, a single detection spot is formed in each of the black-colored regions a 1 , b 1 , c 1 , and d 1 . The detection spots thus formed simultaneously differ from one another in terms of components contained therein. After completion of the first spotting operation, the injection modules 40 a 1 to 40 a 2 are moved above the surface of the slide glass 20 along directions of arrows x and y shown in FIG. 12 in the same sequence as in the above-described forming methods. Thus, detection spots are formed in regions (a 2 , a 3 , a 4 ), regions (b 4 , b 5 , b 6 ), regions (c 6 , c 7 , c 8 ), and regions (d 2 , d 8 , and d 9 ) shown in FIG. 14 in the sequence of the numerals attached to the respective reference letters. When a larger number of types of detection spots must be formed by the detection-spot forming method according to the third embodiment, the injection units 40 d are cleaned and then filled with corresponding spot-forming liquids to thereby prepare for a second injection cycle. Subsequently, in the same manner as in the first injection cycle, the injection units 40 d are caused to jet spot-forming liquids toward detection-spot forming positions in a region adjacent to the group of detection spots which have been formed in the first injection cycle. In this manner, groups of detection spots are formed successively. In the detection-spot forming method of the present embodiment, through repetition of the above-described injection cycle, a predetermined number of detection spots are formed on the surface of the slide glass 20 . By virtue of the above-described operation, four DNA chips or DNA microarrays are simultaneously formed in, for example, four regions of the slide glass 20 . Subsequently, the slide glass 20 is divided along two-dot chain lines shown in FIG. 14 before use. In the above-described detection-spot forming methods according to the first and second embodiments of the present invention, the injection units 10 d, 30 d are used as means for spotting detection spots. Therefore, use of a plurality of injection modules 10 a, 30 a enables simultaneous jetting of spot-forming liquids from the injection units 10 d, 30 d of these injection modules 10 a, 30 a to the surfaces of slide glasses 20 which are equal in number to the injection modules 10 a, 30 a. Use of such a spotting means improves the efficiency of a process of fabricating DNA chips or DNA mircoarrays each having several thousands to several tens of thousands of detection spots. In the above-described detection-spot forming method according to the third embodiment of the present invention, the injection units 40 d are used as means for spotting detection spots. Therefore, use of a plurality of injection modules 40 a enables simultaneous jetting of spot-forming liquids from the injection units 40 d of these injection modules 40 a to regions on the surface of a slide glass 20 , which regions correspond to the respective injection units 40 d. Use of such a spotting means improves the efficiency of a process of fabricating DNA chips or DNA mircoarrays each having several to several hundreds of detection spots. That is, the detection-spot forming methods of the first through third embodiments can shorten the time required to form detection spots during the fabrication of a large number of DNA chips or DNA microarrays each having several thousands to several tens of thousands of detection spots, or DNA chips or DNA microarrays each having several to several hundreds of detection spots, as compared with a conventional detection-spot forming method employing a spotting scheme on the basis of contact with the surface of a support, such as a pin scheme, which can form detection spots on the surface of a single support only through a single spotting operation. Thus, the detection-spot forming methods of the first through third embodiments can provide DNA chips or DNA microarrays at reduced cost. In these detection-spot forming methods, since the injection units 10 d, 30 d, 40 d of the respective injection modules are maintained in a state of use during formation of detection spots, spot-forming liquid within the discharge openings of the injection units do not dry. Therefore, jetting of spot-forming liquid can be performed consistently, and thus, predetermined detection spots can be formed reliably. Further, these detection-spot forming methods reduce the number of movements of the injection modules 10 a, 30 a, 40 a, to thereby suppress drying of spot-forming liquid at the exit ends of the discharge ports of the injection units 10 d, 30 d, 40 d which would otherwise occur due to air flow caused by movement of the injection apparatus 10 , 30 , 40 , and suppress vibration of the discharge ports which occurs due to movement of the injection modules 10 a, 30 a, 40 a. Therefore, during formation of detection spots, spot-forming liquid can be jetted from the injection units 10 d, 30 d, 40 d of the respective injection modules more consistently, and thus, predetermined detection spots can be formed reliably. As a result, quality of DNA chips or DNA microarrays can be improved further. In the detection-spot forming methods according to the first and second embodiments, when the injection modules 10 a, 30 a are successively moved to be located above the surfaces of slide glasses in order to jet spot-forming liquid, some of the injection modules 10 a, 30 a move to positions outside the surfaces of the slide glasses 20 (regions indicated by two-dot chain lines in FIGS. 4 and 9 ). Even in such a case, the injection units 10 d, 30 d of the injection modules 10 a, 30 a located outside the surfaces of the slide glasses 20 are caused to jet spot-forming liquid in order to maintain all the injection units 10 d, 30 d in a state of use. The spot-forming liquid jetted from injection unit 10 d, 30 d of the injection modules located outside the surfaces of the slide glasses 20 can be used for judgment as to whether the state of jetting is proper. This advantageous effect can be attained by the detection-spot forming method according to the third embodiment as well. In this case, the spot-forming liquid jetted from the injection units 40 d located outside the surface of the single slide glass 20 can be used for judgment as to whether the state of jetting is proper. The regions in which the injection modules 10 a, 30 a located outside the surfaces of the slide glasses 20 jet spot-forming liquid are indicated by two-dot chain lines in FIGS. 4 and 9 . The jetting of spot-forming liquid from the injection modules 10 a, 30 a at positions outside the surfaces of the slide glasses 20 does not contribute to formation of detection spots on the surfaces of the slide glasses 20 . Therefore, spotting regions outside the surfaces of the slide glasses 20 are desirably reduced to a possible extent. Such reduction can attained through an increase in the number of slide glasses 20 to be used. In this case, the ratio of spotting regions not contributing to formation of detection spots to the entire region can be reduced in proportion to the number of the slide glasses 20 . This also holds true in the detection-spot forming method according to the third embodiment. In this case, useless consumption of spot-forming liquid can be reduced through an increase in the number of detection-spot forming regions on a single slide glass 20 . The detection-spot forming methods according to the first through third embodiments can be applied not only to fabrication of DNA chips or DNA microarrays, but also to fabrication of bio chips each having detection spots including antibodies as components, and protein chips each having detection spots including proteins as components. In particular, during fabrication of DNA chips or DNA microarrays, spot-forming liquids containing DNA fragments having limited useful lives are handled, and therefore, such detection spots must be formed as quickly as possible. Accordingly, the detection-spot forming methods according to the first through third embodiments are particularly effective for fabrication of DNA chips and DNA microarrays.