JP3876839B2 - Nebulizer chip and high frequency inductively coupled plasma spectrometer using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the field of analytical chemistry, and in particular, a nebulizer for atomizing a liquid sample belonging to the field of μTAS (Micro Total Analysis Systems) that can be realized by the recent MEMS (Micro Electro Mechanical Systems) technology, and a high-frequency inductively coupled plasma ( ICP) relates to a spectroscopic analyzer.
[0002]
[Prior art]
As a general type of conventional nebulizer for ICP, there is a structure (air feeding type) in which a gas for atomization is flowed so as to surround a sample (refer to Patent Document 1). In the pneumatic nebulizer, a sample solution is sucked by a carrier gas (usually argon gas) through a sample introduction capillary on the principle of atomization and sprayed into an atomization chamber to be atomized. The atomized sample is sent to a plasma torch where it is excited and emits light. Of the sample introduced into the atomization chamber, the liquid that has not been atomized is discharged to the drain.
[0003]
The pneumatic atomizer has a problem that the gas consumption is large because it is necessary to continuously flow a carrier gas such as argon gas during the analysis.
Therefore, an ultrasonic nebulizer that atomizes a sample using ultrasonic waves has been developed as a nebulizer that does not use a carrier gas for atomization (see Patent Document 2).
[0004]
In the ultrasonic nebulizer, an ultrasonic wave is generated by applying a high-frequency voltage to an ultrasonic vibrator, and the sample liquid ejected from the capillary is atomized by the vibration. When the sample liquid is sprayed directly on the ultrasonic vibrator, the electrodes of the vibrator are corroded, so that a glass plate is fixed on the surface side of the vibrator and atomized on the surface of the glass plate.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-43304 [Patent Document 2]
Japanese Patent No. 2739533 [0006]
[Problems to be solved by the invention]
In the ultrasonic nebulizer, the sample can be efficiently sent to the plasma part as compared with the pneumatic type, but the mechanism is complicated and the manufacturing cost increases.
The first object of the present invention is to simplify the ultrasonic nebulizer mechanism and reduce the manufacturing cost.
A second object of the present invention is to provide an ICP spectroscopic analysis apparatus equipped with such an improved ultrasonic nebulizer.
[0007]
[Means for Solving the Problems]
A nebulizer of the present invention for achieving the first object is configured as a nebulizer chip, a sample liquid reservoir for introducing a sample, a nebulizer portion having a diaphragm at the bottom of an opening, and the liquid reservoir and the nebulizer portion. A chip member integrated with a flow path for connecting between them, and an ultrasonic transducer that is attached to the back surface of the nebulizer with the chip member and applies ultrasonic vibration to atomize the liquid to the diaphragm.
[0008]
The sample placed in the sample reservoir reaches the diaphragm of the nebulizer section through the flow path. The diaphragm is ultrasonically vibrated by the ultrasonic vibrator on the back surface, and the sample is atomized by the ultrasonic vibration.
[0009]
The nebulizer according to the present invention has a simple structure in which an ultrasonic vibrator is attached to a chip member that is provided with a sample liquid reservoir, a nebulizer section and a flow path as one body. It is possible to achieve a product with
[0010]
In addition, any type of nebulizer has a structure in which the sample introduction part and the atomization part are independent of each other, and when the amount of the sample is very small, a flow path from the sample introduction part to the atomization part is used. The loss of the sample was large and effective analysis was difficult. However, since the nebulizer of the present invention can be manufactured as an integrated nebulizer using the MEMS technology, the capacity of the flow path can be reduced in that case, and the sample waste can be reduced to reduce the amount of sample. However, atomization can be performed efficiently.
[0011]
In the case where only the sample reservoir is connected to the nebulizer section, the sample supplied to the sample reservoir is nebulized as it is, so pretreatment such as causing the sample to perform a predetermined reaction is performed. When it is necessary to apply the sample, the sample after the pretreatment is supplied to the sample reservoir.
[0012]
As another embodiment of the nebulizer of the present invention, such pretreatment can be performed in the flow channel after the sample is supplied to the sample reservoir. As a nebulizer of such an embodiment, the tip member further includes a pretreatment liquid reservoir for pretreating a sample in addition to the sample reservoir, and the flow path extends to the sample reservoir. And a flow path part extending to the pretreatment liquid reservoir, and a flow path part extending from the confluence of both flow path parts to the nebulizer part.
[0013]
In order to achieve the second object, the present invention comprises a nebulizer, an ICP device that emits light from a sample atomized by the nebulizer by plasma, and a spectrometer that receives light from the ICP device and spectrally detects it. In the ICP spectroscopic analyzer provided, the nebulizer chip of the present invention is used as a nebulizer.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The block diagram of the nebulizer chip | tip of one Example is shown in FIG. (A) is a perspective view, (B) is sectional drawing along the flow path in the figure of (A). The glass substrates 2 and 10 are bonded and integrated, and a flow path 4 is formed on the glass substrate 2 side on the bonding surface of both the substrates 2 and 10. Although it does not specifically limit as the glass substrates 2 and 10, For example, a synthetic quartz substrate can be used. A sample reservoir 8 for introducing a sample is formed at one end of the channel 4, and an opening 6 serving as a nebulizer is formed at the other end of the channel 4. The openings 6 and 8 are formed as holes penetrating the glass substrate 2, and are formed in a funnel shape so that the opening is widened on the surface side of the glass substrate 2.
[0015]
The glass substrate 10 is a substrate serving as a diaphragm, and a thickness of 0.1 to 0.5 mm is appropriate. On the back surface side of the glass substrate 10, an ultrasonic vibrator is attached at the position of the nebulizer section 6, and the glass substrate 10 in that portion becomes the diaphragm 10a. The ultrasonic transducer includes a thin film electrode 12 formed on a glass substrate 10, a piezoelectric material thin film 14 formed thereon, and a thin film electrode 16 formed thereon.
[0016]
The material of the piezoelectric material thin film 14 is not particularly limited, but PZT (lead zirconate titanate) or the like can be used, and the material of the electrodes 12 and 16 is not particularly limited, but Pt / Ti A laminated film (Ti layer is on the lower layer side and a Pt layer is laminated thereon. The same applies hereinafter) can also be used.
[0017]
The ultrasonic vibrator is ultrasonically vibrated by applying a high-frequency voltage between the electrodes 12 and 16, and the vibration is transmitted to the liquid in the nebulizer 6 through the diaphragm 10a.
[0018]
The flow path 4 is a minute one having a width of 20 to 200 μm, a height of 20 to 100 μm, and a length of 0.5 to 20 mm, and the areas of the bottoms of the liquid reservoir 8 and the nebulizer part 6 are also minute.
[0019]
FIG. 2 schematically shows an embodiment of an ICP spectroscopic analyzer using this nebulizer chip. A plasma torch 20 is attached to the opening of the nebulizer portion 6 of the nebulizer chip. The plasma torch 20 includes a high frequency induction coil 22 to which a high frequency voltage is applied from a high frequency power source.
[0020]
A spectroscope 28 is connected to the plasma torch 20 in order to spectrally detect light emitted from the plasma by the plasma torch 20. Reference numeral 26 denotes light emission generated by the plasma torch 20, which is guided to the spectroscope 28 and detected. The spectroscope 28 includes an entrance slit 30 for taking in the light emission 26, a concave diffraction grating 32 for dispersing the taken-in light, and a photodiode array 34 as a detector for detecting light dispersed by the concave diffraction grating 32. A polychromator that simultaneously detects the dispersed light over a predetermined range is configured.
[0021]
In the embodiment of FIG. 2, when the sample solution is put into the liquid reservoir 8, the sample solution is guided to the nebulizer section 6 through the flow path 4. In the nebulizer section 6, ultrasonic vibration is applied to the diaphragm 10a by an ultrasonic vibrator made of the piezoelectric material thin film 14, and the ultrasonic vibration is transmitted to the sample solution, so that the sample solution is atomized. The atomized vapor of the sample is guided to the plasma torch 20, emits plasma by the high frequency induction coil 22, and is dispersed and detected by the spectroscope 28.
[0022]
FIG. 3 shows another embodiment of the nebulizer chip. This embodiment is provided with a reservoir for pretreatment liquid, and the sample is mixed with the pretreatment liquid and guided to the nebulizer section, so that the sample is detected after pretreatment. .
[0023]
The nebulizer chip shown in FIG. 3 is the same as the embodiment shown in FIG. 1 in that the chip is formed by bonding the glass substrates 2 and 10 and an ultrasonic transducer is provided on the back surface of the glass substrate 10. The difference is that a sample reservoir 8s and a pretreatment liquid reservoir 8p are provided. Accordingly, the flow path includes a flow path section 4s extending to the liquid reservoir 8s and a flow path section 4p extending to the pretreatment liquid reservoir 8p. The flow path section 4r extends from the junction of the flow path sections to the nebulizer section. Yes. The flow path portion 4r is a reaction flow path for allowing the sample to be mixed with the pretreatment liquid and for the reaction to occur.
[0024]
The nebulizer chip of FIG. 3 is also combined with a plasma torch and a spectroscope as shown in FIG. 2 and used as an ICP spectroscopic analyzer. The operation is the same as that shown in FIG.
[0025]
The nebulizer chip manufacturing method of the embodiment of FIG. 1 will be described with reference to FIG. 4, but the nebulizer chip manufacturing method of the embodiment of FIG. 3 is the same.
(1) First, a metal film 40 serving as an etching protective film, such as a chromium film, is formed on the glass substrate 2 by means such as vapor deposition or sputtering.
[0026]
(2) Next, photolithography is performed to pattern the etching protective film 40. Photolithographies are usually used in semiconductor processes. Photoresist is exposed with an exposure device using a photomask with an opening pattern that forms a flow path to obtain a desired pattern. Thereafter, the photoresist is developed with a developing device to obtain a photoresist pattern 42. The photoresist may be positive or negative.
[0027]
(3) The metal film 40 is etched using the photoresist pattern 42 patterned into a desired shape having an opening pattern in the shape of a flow path as a mask. When the metal film 40 is a chromium film, it is possible to perform etching at room temperature using a commercially available etchant. Thereby, the metal film pattern 40 from which only the portion of the glass substrate 2 where the glass substrate 2 is desired to be etched is removed is obtained.
[0028]
(4) Glass etching is performed using the metal film pattern 40 obtained in the step (3) as a mask to form a groove serving as a flow path in the glass substrate 2. As an etching means for the glass substrate 2, a wet etching method using a solution such as hydrofluoric acid or a dry etching method using plasma can be used.
[0029]
(5) The through holes 6 and 8 are formed at both ends of the groove serving as the flow path by a method such as ultrasonic processing or sandblasting from the opposite side to the processing surface so far. The holes 6 and 8 serve as a nebulizer port for atomizing the sample and a sample introduction port (liquid reservoir).
[0030]
(6) Next, a metal film (for example, a Pt / Ti laminated film) 12 serving as an electrode is formed on another glass substrate 10, and a thin film electrode shape is formed thereon by photolithography as in the step (2). A photoresist pattern is formed.
[0031]
(7) Using the photoresist pattern as a mask, the metal film 12 is etched and patterned to form the first electrode 12.
[0032]
(8) A piezoelectric material thin film 14, for example, a PZT thin film, is formed on the first electrode 12, and a photoresist pattern having a vibrating portion shape is formed thereon by photolithography in the same manner as in the step (2).
[0033]
(9) Unnecessary PZT thin film 14 is removed by a method such as ion milling using the photoresist pattern as a mask to form a piezoelectric element of the vibrating portion.
[0034]
(10) A metal film (for example, a PT / Ti laminated film) 16 serving as a second electrode is formed on the substrate on the PZT thin film 14 side of the vibration part, and then by photolithography in the same manner as in the step (2). A photoresist pattern having a second electrode shape is formed.
[0035]
(11) The metal film 16 is etched using the photoresist pattern as a mask to form a second electrode.
[0036]
(12) A method such as fusing the produced two glass plates 2 and 10 so that a groove serving as a flow path of the glass plate 2 is on the inner side and the ultrasonic vibration element on the glass plate 10 is on the back surface side. To join.
[0037]
【The invention's effect】
The nebulizer chip of the present invention is provided with a sample liquid reservoir on a chip member, a nebulizer part provided with a diaphragm at the bottom of the opening, and a flow path connecting them, and an ultrasonic transducer on the back surface of the nebulizer part Since the structure is simple and can be manufactured by MEMS technology, it is possible to realize a low-priced and quality product as a single nebulizer.
Further, this nebulizer chip can be combined with a fluid element such as a valve or a pump, and a high-function analyzer can be realized.
The ICP spectroscopic analysis apparatus of the present invention using this nebulizer chip can produce a nebulizer chip by MEMS technology, so that it is possible to efficiently atomize a small amount of sample, and high sensitivity of a small amount of sample. Analysis becomes possible.
[Brief description of the drawings]
1A and 1B are diagrams showing a nebulizer chip according to an embodiment, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view taken along a flow path in FIG.
FIG. 2 is a schematic cross-sectional view showing an example of an ICP spectroscopic analyzer using the nebulizer chip of the example.
FIG. 3 is a perspective view showing a nebulizer chip according to another embodiment.
4 is a process cross-sectional view illustrating a method for manufacturing the nebulizer chip of the embodiment of FIG. 1; FIG.
[Explanation of symbols]
2,10 Glass substrate 4 Flow path 6 Nebulizer portion 8 Sample reservoir 10a Diaphragm 12, 16 Thin film electrode 14 Piezoelectric material thin film 20 Plasma torch 28 Spectrometer

Claims (3)

A sample liquid reservoir for performing sample introduction, a nebulizer portion provided with a diaphragm at the bottom of the opening, and a chip member integrated with a flow path connecting the liquid reservoir and the nebulizer portion;
The nebulizer chip | tip provided with the ultrasonic transducer | vibrator attached to the back surface of the said nebulizer part with the said chip member, and providing the ultrasonic vibration which atomizes a liquid to the said diaphragm. In addition to the sample reservoir, the tip member further includes a pretreatment liquid reservoir for preprocessing the sample, and the channel includes a channel portion extending to the sample reservoir, and the pretreatment 2. The nebulizer chip according to claim 1, comprising a flow path portion extending to the liquid reservoir and a flow path portion extending from the merging point of both flow path portions to the nebulizer portion. A high frequency inductively coupled plasma comprising: a nebulizer; a high frequency inductively coupled plasma device that emits light from the sample atomized by the nebulizer by plasma; and a spectrometer that receives light from the high frequency inductively coupled plasma device and spectrally detects the light. In the spectroscopic analyzer,
3. A high frequency inductively coupled plasma spectroscopic analyzer using the nebulizer chip according to claim 1 or 2 as the nebulizer.

Images