Patent Publication Number: US-2018052083-A1

Title: Chemical substance concentrator

Description:
TECHNICAL FIELD 
     The disclosure relates to a chemical substance concentrator capable of condensing volatile organic compounds in a sample. 
     BACKGROUND ART 
     Volatile organic compounds (VOC) are contained in, e.g. exhaust gas, the air, and exhalation. In a conventional detection system for detecting volatile organic compounds contained in a sample, the volatile organic compounds are adsorbed on an adsorption part. After that, the detection system desorbs the volatile organic compounds from the adsorption part. The desorbed volatile organic compounds are detected by a detection unit. 
     PTL 1 is known as a prior art relating to the above-mentioned conventional detection system. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Laid-Open Publication No. 2012-220454 
     SUMMARY 
     A chemical substance concentrator includes a tubular body, and adsorption parts provided at predetermined intervals on a surface of the tubular body facing the inside of the tubular body. 
     The chemical substance concentrator allows a sample to easily pass through the chemical substance concentrator. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a chemical substance concentrator in accordance with an exemplary embodiment. 
         FIG. 2  is a top view of the chemical substance concentrator in accordance with the embodiment. 
         FIG. 3A  is a cross-sectional view of the chemical substance concentrator along line  3 A- 3 A shown in  FIG. 2 . 
         FIG. 3B  is a cross-sectional view of the chemical substance concentrator along line  3 B- 3 B shown in  FIG. 2 . 
         FIG. 3C  is an enlarged view of the chemical substance concentrator in accordance with the embodiment. 
         FIG. 4A  is a side cross-sectional view of another chemical substance concentrator in accordance with the embodiment. 
         FIG. 4B  is a cross-sectional side view of still another chemical substance concentrator in accordance with the embodiment. 
         FIG. 4C  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 4D  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 4E  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 4F  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 4G  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 4H  is a side cross-sectional side view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 5  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 6  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 7  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
         FIG. 8  is a side cross-sectional view of a further chemical substance concentrator in accordance with the embodiment. 
     
    
    
     DETAIL DESCRIPTION OF PREFERRED EMBODIMENT 
     A chemical substance concentrator in accordance with an exemplary embodiment of the present disclosure will be detailed below with reference to the drawings. Note that, each exemplary embodiment described in the following shows a preferable specific example of the present disclosure. Accordingly, the numerical values, shapes, materials, structural elements, the arrangement and connection of the structural elements, and the like shown in the following embodiment are mere examples, and thus are not intended to limit the present disclosure. Therefore, among the structural elements in the following embodiment, structural elements not recited in any one of the independent claims representing the most generic concepts of the present invention are described as arbitrary structural elements. 
     Besides, each view is a schematic diagram but not necessarily illustrated exactly. In each view, the same reference numerals denote the substantially same structures, and a redundant description may be omitted or simplified. 
       FIG. 1  is a perspective view of chemical substance concentrator  10  in accordance with an exemplary embodiment.  FIG. 2  is a top view of chemical substance concentrator  10  for schematically showing an inside of chemical substance concentrator  10 .  FIG. 3A  is a cross-sectional view of chemical substance concentrator  10  along line  3 A- 3 A shown in  FIG. 2 .  FIG. 3B  is a cross-sectional view of chemical substance concentrator  10  along line  3 B- 3 B shown in  FIG. 2 . 
     Chemical substance concentrator  10  is configured to adsorb molecules of a chemical substance contained in a sample. The sample is, e.g. gas, such as exhaust gas, the living space air, or human exhalation. The chemical substance is, e.g. a volatile organic compound (VOC). 
     Chemical substance concentrator  10  includes tubular body  11 , adsorption part  12 , and desorption part  94 . 
     Tubular body  11  has inlet  16  for taking the sample into an inside of tubular body  11 , and has outlet  17  for discharging the sample to the outside of tubular body  11 . Flow passage  13  is formed inside tubular body  11  such that the sample flows from inlet  16  to outlet  17  in flow direction D 10  to allow the sample to pass through the flow passage  13 . Tubular body  11  may have various shapes, such as a cylinder tube or a rectangular tube. Tubular body  11  shown in  FIG. 1  has a cross section having a rectangular shape. As shown in  FIG. 3B , tubular body  11  has inner surfaces  11 A and  11 B that face flow passage  13  and are opposed to each other, outer surface  11 C that is opposite to inner surface  11 A, and outer surface  11 D that is opposite to inner surface  11 B. Inner surfaces  11 A and  11 B constitute flow passage  13 . 
     In accordance with the embodiment, flow passage  13  has a cross section having width W of 1 mm and height H 1  of 30 μm. Flow passage  13  has length L of 10 mm. 
     Tubular body  11  may be made of insulating material. Alternatively, tubular body  11  may be made of material having a surface which faces flow passage  13  and is covered with an insulator. Tubular body  11  may be made of, for example, insulators, such as glass, quartz, sapphire, or ceramic, or a silicon substrate having thermal silicon oxide formed on a surface thereof. 
     Inner surfaces  11 A and  11 B of tubular body  11  may be made of materials different from each other. In this case, a material forming tubular body  11  may be exposed from either one of inner surface  11 A or inner surfaces  11 B. 
     Adsorption part  12  adsorbs molecules of a chemical substance contained in the sample. Plural adsorption parts  12  are provided on inner surface  11 A of tubular body  11  to be spaced from one another with predetermined interval B 1 . Adsorption part  12  has a circular column shape. Adsorption part  12  has end  12 A and end  12 B opposite to end  12 A. End  12 A of adsorption part  12  is fixed onto inner surface  11 A of tubular body  11 . In chemical substance concentrator  10 , end  12 B is provided on and fixed to inner surface  11 B of tubular body  11 . 
       FIG. 3C  is an enlarged view of chemical substance concentrator  10 , and shows the periphery of adsorption part  12 . Adsorption part  12  includes plural dense fibers  15 . Fibers  15  forming adsorption part  12  increase a surface area of adsorption part  12 . Sample A 10  contains medium B 10  of gas and molecules C 10  of a chemical substance floating in medium B 10 . Adsorption part  12  is implemented by an aggregation of fibers  15  and has a surface with depressions and projections, thereby adsorbing molecules C 10  of the chemical substance while rolling sample A 10  (medium B 10 ) of gas, as shown in  FIG. 3C . 
     Interval B 1  (see  FIG. 2 ) between adsorption parts  12  adjacent to each other in a cross section of tubular body  11  perpendicular to flow direction D 10  is larger than interval D 15  between fibers  15  in the cross section of tubular body  11 . 
     Fiber  15  has anisotropic properties. A layer for controlling a growing direction of fibers  15 , a material layer serving as a core of fiber  15 , and a catalyst layer are formed on inner surface  11 A. After that, fibers  15  are grown by a vapor phase method or a liquid phase method. Fibers  15  are preferentially oriented in a direction substantially perpendicular to inner surface  11 A. 
     Fibers  15  are made of metal oxides, such as ZnO, SnO 2 , In 2 O 3 , In 2-x Sn x O 3  (for instance, 0.1≦x≦0.2), NiO, CuO, TiO 2 , and SiO 2 . Oxygen on a surface of the metal oxide interacts with molecules of the chemical substance, thereby adsorbing the molecules of the chemical substance efficiently. Fiber  15  is made of a nanowire or a nanofiber. 
     Fiber  15  is covered with adsorption material  115  for adsorbing molecules of the chemical substance selectively. 
     For instance, in the case that carbon monoxide is adsorbed selectively, nickel and silver may be used as adsorption material  115 . Further, in the case that ammonia or chlorine is adsorbed, molybdenum may be used as adsorption material  115 . In the case that nitrogen oxide is adsorbed, zeolite may be used as adsorption material  115 . In the case that hydrogen is adsorbed, palladium may be used as adsorption material  115 . In the case that water is adsorbed, poly aniline may be used as adsorption material  115 . In the case that molecules of a polar organic substance are adsorbed, a polyethylene glycol or PDMS (polydimethyl siloxane) may be used as adsorption material  115 . In this case, adsorption material  115  is preferably made of a material having a surface having the same polarity as surfaces of the molecules. The material of adsorption material  115  can be selected according to the molecules of the chemical substance to be adsorbed as necessary. 
     Fiber  15  may be made of adsorption material  115  for adsorbing molecules of the chemical substance selectively. If fiber  15  forming adsorption part  12  adsorbs molecules of the chemical substance by itself, fiber  15  may not be covered with adsorption material  115 . 
     In accordance with the embodiment, an average diameter of adsorption part  12  is more than or equal to several tens micrometers and less than or equal to several hundred micrometers. In accordance with the embodiment shown in  FIG. 2 , average diameter D 1  of adsorption part  12  is approximately 200 μm. 
     One adsorption part  112  out of plural adsorption parts  12  is spaced from another adsorption part  212  out of plural adsorption parts  12  which is adjacent to adsorption part  112  by an interval B 1  of about 200 μm. Plural adsorption parts  12  are meanderingly arranged such that centers  12 C of adsorption parts  12  which are located close to one another in flow direction D 10  do not overlap one another viewing in flow direction D 10 . In chemical substance concentrator  10  according to the embodiment, plural adsorption parts  12  are meanderingly arranged such that centers  12 C of adsorption parts  12  adjacent to one another in flow direction D 10  do not overlap viewing in flow direction D 10 . 
     The sample passes through between plural adsorption parts  12  to flow from inlet  16  to outlet  17  in flow direction D 10 . At this moment, the sample hardly flows into between plural fibers  15  in single adsorption part  12 . This is because a pressure loss within single adsorption part  12  is substantially three or four orders of magnitude larger than a pressure loss between plural adsorption parts  12  since fibers  15  are densely gathered in single adsorption part  12 . 
     In accordance with the embodiment, height H 2  of adsorption part  12  in height direction DH directed from inner surface  11 A to inner surface  11 B is 30 μm. Adsorption part  12  extends from inner surface  11 A to inner surface  11 B. In other words, height H 1  of flow passage  13  in height direction DH is equal to height H 2  of adsorption part  12 , i.e., 30 μm in accordance with the embodiment. 
     Desorption part  94  is provided on outer surface  11 C of tubular body  11  opposite to inner surface  11 A. Desorption part  94  desorbs the molecules of the chemical substance which has been adsorbed on adsorption part  12  from adsorption part  12  to return the desorbed molecules into the sample. Thus, chemical substance concentrator  10  can condense the chemical substance contained in the sample. 
     The desorbed molecules of the chemical substance are detected by, for example, a sensor provided downstream in flow direction D 10  with respect to chemical substance concentrator  10 . Further, the adsorbed molecules of the chemical substance can be desorbed to recover the adsorbing function of adsorption part  12 . 
     In chemical substance concentrator  10  shown in  FIGS. 1 to 3C , desorption part  94  is implemented by heating unit  14  that is connected to external power source  18  and heats adsorption parts  12 . Heating unit  14  in accordance with the embodiment is implemented by, e.g. a metal wire or a wiring pattern made of resistance heating material. For instance, heating unit  14  may be made of a NiCr thin film having a meandering shape. 
       FIG. 4A  is a cross-sectional view of another chemical substance concentrator  10 A in accordance with the embodiment. In  FIG. 4A , components identical to those of chemical substance concentrator  10  shown in  FIGS. 1 to 3C  are denoted by the same reference numerals. In chemical substance concentrator  10 A shown in  FIG. 4A , heating unit  14  serving as desorption part  94  is provided inside tubular body  11 . Specifically, heating unit  14  is provided between tubular body  11  and each of adsorption parts  12 . Insulating layer  20  is provided between heating unit  14  and each of adsorption parts  12 . A current flowing in heating unit  14  can hardly flow into adsorption part  12 . As a result, heating unit  14  can heat adsorption part  12  efficiently. Heating unit  14  has surface  14 A and surface  14 B opposite to surface  14 A. Insulating layer  20  has surface  20 A and surface  20 B opposite to surface  20 A. Surface  14 B of heating unit  14  is provided on inner surface  11 A of tubular body  11 . Surface  20 B of insulating layer  20  is provided on surface  14 A of heating unit  14 . Surface  20 A of insulating layer  20  faces flow passage  13 . In chemical substance concentrator  10 A, end  12 A of adsorption part  12  is provided on surface  20 A of insulating layer  20 . Insulating layer  20  is extremely thin, and thus allows adsorption part  12  to substantially contact heating unit  14 . 
       FIG. 4  B is a cross-sectional view of still another chemical substance concentrator  10 B in accordance with the embodiment. In  FIG. 4B , components identical to those of chemical substance concentrator  10 A shown in  FIG. 4A  are denoted by the same reference numerals. Chemical substance concentrator  10 B shown in  FIG. 4B  does not include insulating layer  20  of chemical substance concentrator  10 A shown in  FIG. 4A . In chemical substance concentrator  10 B, adsorption part  12  has dielectric properties. Surface  14 A of heating unit  14  faces flow passage  13 . In chemical substance concentrator  10 B, ends  12 A of adsorption parts  12  are provided on heating unit  14 . Adsorption part  12  may not have dielectric properties. 
     Adsorption part  12  implemented by an aggregation of fibers  15  has a small heat capacity depending on its structure. In chemical substance concentrators  10 A and  10 B shown in  FIGS. 4A and 4B , adsorption part  12  contacts heating unit  14  or substantially contacts heating unit  14 , thereby heating adsorption part  12  efficiently and desorbing molecules C 10  which have been adsorbed. Therefore, adsorption part  12  made of fibers  15  can desorb the chemical substance with little power consumption. 
     Heating unit  14  may be made of material, such as a metal wire or a resistive heating material, generating heat. For instance, heating unit  14  includes heating sections A 14  each facing respective one of adsorption parts  12  and connecting sections B 14  for connecting heating sections A 14  in series. In chemical substance concentrator  10 A shown in  FIG. 4A , each of heating sections A 14  of heating unit  14  faces respective one of ends  12 A of adsorption parts  12  across thin insulating layer  20 , and substantially contacts respective one of ends  12 A of adsorption parts  12 . In chemical substance concentrator  10 B shown in  FIG. 4B , each of heating sections A 14  of heating unit  14  contacts respective one of ends  12 A of adsorption parts  12 . Heating section A 14  is made of a heat generating material that is patterned on a surface of end  12 A of adsorption part  12 , or a part of surface  20 B of insulating layer  20  facing end  12 A. The area of connecting section B 14  is smaller than that of heating section A 14 . This configuration can heat only adsorption part  12 . Thus, a cooling rate after the heating can be raised to adsorb and desorb molecules C 10  of the chemical substance at high speed, thereby operating adsorption part  12  with small power consumption. 
       FIG. 4C  is a cross-sectional view of further chemical substance concentrator  10 C in accordance with the embodiment. In  FIG. 4C , components identical to those of chemical substance concentrator  10  shown in  FIG. 3A  are denoted by the same reference numerals. Chemical substance concentrator  10 C includes heating unit  114  serving as desorption part  94  for heating adsorption part  12 , instead of heating unit  14  of chemical substance concentrator  10  shown in  FIG. 3A . Heating unit  114  includes lower electrode  141 , nanofibers  142 , and upper electrode  143 . Nanofibers  142  are formed between lower electrode  141  and upper electrode  143 . Nanofibers  142  have conductivity. Nanofibers  142  are electrically connected to lower electrode  141  and upper electrode  143 . Lower electrode  141  and upper electrode  143  are connected to external power source  18 . Upper electrode  143  is provided on outer surface  11 C of tubular body  11 . 
     Upon having currents flow, nanofibers  142  generate heat due to resistances included in nanofibers  142 . Accordingly, nanofibers  142  can be used as heating unit  14  of chemical substance concentrator  10  shown in  FIG. 3A . 
     Nanofibers  142  heat up heating unit  114  to a high temperature with little electric power. Therefore, adsorption part  12  can be heated efficiently with small electric power. Nanofibers  142  have a small heat capacity, and allow heating unit  114  to be cool at a high speed. Therefore, heating unit  114  using nanofiber  142  can heat or cool adsorption part  12  more quickly. 
     Fibers  15  of adsorption part  12  and nanofibers  142  of heating unit  14  may be made of the same material. Alternatively, fibers  15  and nanofibers  142  may be formed of different materials. 
     Chemical substance concentrators  10 A and  10 B shown in  FIGS. 4A and 4B  may include heating unit  114  shown in  FIG. 4C , instead of heating unit  14 . 
       FIG. 4D  is a cross-sectional view of further chemical substance concentrator  10 D in accordance with the embodiment. In  FIG. 4D , components identical to those of chemical substance concentrator  10 A shown in  FIG. 4A  are dented by the same reference numerals. Chemical substance concentrator  10 D includes vibrator  24  serving as desorption part  94 , instead of heating unit  14  of chemical substance concentrator  10 A shown in  FIG. 4A . By vibrating adsorption part  12 , vibrator  24  desorbs molecules C 10  of the chemical substance adsorbed on adsorption part  12 . Vibrator  24  has lower electrode  241 , piezoelectric body  242 , and upper electrode  243 . Lower electrode  241  has surface  241 A and surface  241 B opposite to surface  241 A. Piezoelectric body  242  has surface  242 A and surface  242 B opposite to surface  242 A. Upper electrode  243  has surface  243 A and surface  243 B opposite to surface  243 A. Piezoelectric body  242  is provided between lower electrode  241  and upper electrode  243 . Surface  241 B of lower electrode  241  is situated on inner surface  11 A of tubular body  11 . Surface  242 B of piezoelectric body  242  is situated on surface  241 A of lower electrode  241 . Surface  243 B of upper electrode  243  is situated on surface  242 A of piezoelectric body  242 . Insulating layers  20  are disposed on surface  243 A of upper electrode  243 . Ends  12 B of adsorption parts  12  are bonded to surface  243 A of upper electrode  243  via insulating layers  20 . An alternating voltage with a frequency ranging from 1 MHz to 1 GHz can be applied between lower electrode  241  and upper electrode  243  to vibrate piezoelectric body  242  so as to desorb molecules C 10  of the chemical substance, which is adsorbed on adsorption part  12  due to the vibration. Piezoelectric body  242  is made of piezoelectric materials, such as Pb(Zr,Ti)O 3  (lead zirconate titanate) or AlN(aluminum nitride). 
       FIG. 4E  is a cross-sectional view of further chemical substance concentrator  10 E in accordance with the embodiment. In  FIG. 4E , components identical to those of chemical substance concentrator  10 D shown in  FIG. 4D  are denoted by the same reference numerals. Chemical substance concentrator  10 E shown in  FIG. 4E  includes vibrator  124 , instead of vibrator  24  of chemical substance concentrator  10 D shown in  FIG. 4D . In chemical substance concentrator  10 D shown in  FIG. 4D , adsorption parts  12  are provided on single vibrator  24 . In chemical substance concentrator  10 E shown in  FIG. 4E , vibrator  124  has regions  124 A to  124 C separated from one another. Each of regions  124 A to  124 C of vibrator  124  includes lower electrode  241 , piezo-electric body  242 , and upper electrode  243 . This configuration reduces a capacitance of each of regions  124 A to  124 C of vibrator  124 , and increases resonance frequencies of regions  124 A to  124 C of vibrator  124 , hence easily driving and vibrating regions  124 A to  124 C of vibrator  124  at a high frequency. Vibrator  124  can vibrate regions  124 A to  124 C at different frequencies or at different timings, so that the adsorbed molecules of a chemical substance can selectively be desorbed. 
       FIG. 4F  is a cross-sectional view of further chemical substance concentrators  10 F in accordance with the embodiment. In  FIG. 4F , components identical to those of chemical substance concentrator  10  shown in  FIG. 3A  are denoted by the same reference numerals. Chemical substance concentrator  10 F includes light irradiation unit  34  functioning as desorption part  94 , instead of heating unit  14  of chemical substance concentrator  10  shown in  FIG. 3A . Light irradiation unit  34  is provided on outer surface  11 D of tubular body  11 . Light irradiation unit  34  irradiates adsorption part  12  with light so as to desorb molecules C 10  of the chemical substance adsorbed on adsorption part  12 . In chemical substance concentrator  10 F, tubular body  11  may preferably be made of material, such as glass, having a high light-transmissible. For instance, a halogen lamp, a laser, a near-infrared lamp, an infrared lamp, and the like can be employed as light irradiation unit  34 . 
     Heating units  14  and  114 , vibrators  24  and  124 , and light irradiation unit  34  function as desorption part  94  for desorbing molecules C 10  of the chemical substance adsorbed on adsorption part  12 . Chemical substance concentrators  10 , and  10 A to  10 F do not necessarily include desorption part  94 . 
     A current may flow to an electrode connected to fiber  15  of adsorption part  12 . Thus, adsorption part  12  per se functions as a heating unit. 
     The shape of adsorption part  12  may not necessarily have a circular column shape. For instance, adsorption part  12  may have an elliptic column shape or a polygonal column shape. Adsorption part  12  may have a conical shape, a pyramid shape, or an elliptic cone shape. 
       FIG. 4G  is a top view of further chemical substance concentrator  10 G in accordance with the embodiment. In  FIG. 4G , components identical to those of chemical substance concentrator  10  shown in  FIG. 2  are denoted by the same reference numerals. As shown in  FIG. 4G , adsorption parts  12  are arranged at intervals in a row in flow direction D 10  directed from inlet  16  to outlet  17  while centers  12 C overlap in flow direction D 10 . This configuration reduces a pressure loss of fluid, and facilitates the sample to pass through flow passage  13  even if a pump with a small size and a low transport capacity is employed. 
     In the above-mentioned conventional detection system, carbon nanofiber is charged inside a tubular body as an adsorbent to provide an adsorption part. However, if the charged adsorbent has a high density, a pressure loss of the adsorption part will be increased. For that reason, the sample hardly passes through the adsorption part. 
       FIG. 4H  is a cross-sectional view of further chemical substance concentrator  10 H in accordance with the embodiment. In  FIG. 4H , components identical to those of chemical substance concentrator  10 G shown in  FIG. 4G  are denoted by the same reference numerals. In chemical substance concentrator  10 H, adsorption parts  12  are arranged in a row without an interval in flow direction D 10 . In this case, adsorption parts  12  arranged along flow direction D 10  are regarded as a single element. Interval D 15  between adjacent fibers  15  arranged along flow direction D 10  in the single element is smaller than interval B 1  (see  FIG. 2 ) between adsorption part  112  and adsorption part  212  in a direction perpendicular to flow direction D 10 . This configuration increases the density of adsorption part  12  while a pressure loss of fluid is reduced. Thus, the sample can efficiently be adsorbed on adsorption part  12 . 
     Further, adsorption part  12  may not necessarily be implemented by an aggregation of fibers  15 . Adsorption part  12  may be made of a material, such as a porous body, having numerous micro-voids. 
     An operation of chemical substance concentrator  10  will be described below. 
     The sample containing molecules of the chemical substance is inserted into chemical substance concentrator  10 . Those molecules are adsorbed on adsorption parts  12  provided inside the flow passage. 
     For instance, in chemical substance concentrator  10  in accordance with the embodiment, height H 1  of flow passage  13  is 30 μm, and width W of flow passage  13  in a direction perpendicular to height H 1  and flow direction D 10  is 1 mm. In the case that the flow rate is 1 ml/min, chemical substance concentrator  10  has a pressure loss of about 3.2 kPa, and the Reynolds number is 4.9. In the case that the flow rate is 5 ml/min, chemical substance concentrator  10  has a pressure loss of about 16 kPa, and the Reynolds number is 24.7. In the case that the flow rate is 10 ml/min, chemical substance concentrator  10  has a pressure loss of about 31.9 kPa, and the Reynolds number is 49.3. 
     With such a configuration, for example, a small sized pump with a maximum static pressure of 80 kPa can be used to insert the sample into chemical substance concentrator  10 . 
     A comparative example of a chemical substance concentrator in which adsorption part  12  is provided over the entire cross section of the flow passage will be described below. When the sample passes through the chemical substance concentrator at a flow rate of 1 ml/min, a pressure loss of the chemical substance concentrator is more than about 100000 kPa. For that reason, a small sized pump with a small capacity can hardly insert the sample into the chemical substance concentrator of the comparative example. 
     As shown in  FIG. 3C , inserted sample A 10  flows so as to flow around adsorption part  12  as a laminar flow, and flows along flow passage  13 . At this moment, vortexes are produced around adsorption part  12  due to sub-micron to micron-sized depressions and projections caused by fibers  15  constituting adsorption part  12 . Heavy substances, such as VOC, contained in the sample receive a centrifugal force due to the vortexes and hit fibers  15 , so that adsorption part  12  can adsorb molecules more effectively than a typical adsorption part having a circular column shape. 
     When sample A 10  is inserted into chemical substance concentrator  10 , the Reynolds number is preferably smaller than 3000. This configuration allows sample A 10  to flow behind adsorption part  12  as a laminar flow. 
     The Reynolds number is preferably smaller than 150. This configuration prevents a Karman vortex from being produced behind adsorption part  12 . Accordingly, sample A 10  also flows around behind adsorption part  12 , so that more molecules C 10  of the chemical substance are adsorbed. 
       FIG. 5  is a side cross-sectional view of further chemical substance concentrator  30  in accordance with the embodiment. In  FIG. 5 , components identical to those of chemical substance concentrator  10  shown in  FIGS. 1 to 3C  are denoted by the same reference numerals. Chemical substance concentrator  30  is different from chemical substance concentrator  10  in that a space is provided above adsorption part  12 . The other structures are the same as chemical substance concentrator  10 . 
     Chemical substance concentrator  30  includes tubular body  11  and adsorption parts  12  provided on inner surface  11 A of tubular body  11 . End  12 B of adsorption part  12  is provided on inner surface  11 A while end  12 A faces inner surface  11 B with an interval between end  12 B and inner surface  11 B. 
     A space through which the sample flows is formed above adsorption part  12 , i.e., between end  12 A of adsorption part  12  and inner surface  11 B. 
     For instance, height H 3  of flow passage  13 , i.e., a distance between inner surface  11 A and inner surface  11 B is 40 μm, and height H 2  of adsorption part  12  is 30 μm. Adsorption section  12  does not contact inner surface  11 B. In other words, chemical substance concentrator  30  has a two-layer structure, i.e., region  31  in which adsorption part  12  is formed and region  32  in which adsorption part  12  is not formed. 
     The pressure loss of chemical substance concentrator  30  can be calculated in the state a flow passage in which adsorption part  12  is formed and a flow passage in which adsorption part  12  is not formed are connected in parallel. 
     A pressure loss of region  31  in which adsorption part  12  is formed is larger than a pressure loss of region  32  in which adsorption part  12  is not formed. If a difference between the pressure losses of region  31  and region  32  increases, the sample hardly flow into region  31  in which adsorption part  12  is formed. For that reason, the pressure loss of region  31  is preferably identical to the pressure loss of region  32 , or the difference between the pressure losses of regions  31  and  32  is about one digit order. 
       FIG. 6  is a side cross-sectional view of further chemical substance concentrator  30 A in accordance with the embodiment. In  FIG. 6 , components identical to those of chemical substance concentrator  30  shown in  FIG. 5  are denoted by the same reference numerals. In chemical substance concentrator  30 A shown in  FIG. 6 , adsorption part  12  inclines so as to extend toward inlet  16  of flow passage  13 . End  15 B of fiber  15  is disposed on inner surface  11 A. End  15 A of fiber  15  is located closer to inlet  16  of flow passage  13  than end  15 B of fiber  15  is. In other words, fiber  15  extends from inner surface  11 A and inclines at an acute angle with respect to flow direction D 10  of the sample. That is, ends  12 B of adsorption parts  12  are located more downstream in flow direction D 10  of the sample than ends  12 A. 
     The sample also enters between fibers  15  of adsorption part  12  easily. For that reason, molecules of the chemical substance are adsorbed not only on end  12 A, which is an upper surface of adsorption part  12 , but also on fibers  15  located inside adsorption part  12 . 
     Fibers  15  inclining toward inlet  16  are made of crystal fibers. For instance, in the case that the fibers are made of hexagonal ZnO, a crystal layer is formed as a core of fiber  15 . The crystal layer is formed by sputtering, such as PVD (Physical Vapor Deposition). 
     Vaper-deposited particles formed by sputtering flow over a wide solid angle. A c-axis direction of the obtained columnar crystal grows with dispersion from an axis perpendicular to a substrate surface. The dispersion strongly depends on a flowing angle of the particles. 
     In a sputtering apparatus, a target is offset, and a region directly above a target erosion part is masked with a shielding plate. Accordingly, the sputtering apparatus sputters particles to prevent the particles from flowing in a vertical component thereof. As a result, a crystal layer of a columnar crystal oriented in the c-axis inclining in one direction with respect to the substrate surface is obtained. 
     The fibers are formed on the formed crystal layer by a vapor phase method or a liquid phase method, thereby obtaining fibers  15  inclining with respect to the substrate surface. For instance, inner surface  11 A of tubular body  11  is used as a flat surface of the substrate, fibers  15  can be formed to incline at any angle with respect to flow direction D 10 . The angle ranges, for example, from 45 degree to 80 degree. 
       FIG. 7  is a side cross-sectional view of further chemical substance concentrator  40  in accordance with the embodiment. In  FIG. 7 , components identical to those of chemical substance concentrator  10  shown in  FIGS. 1 to 3C  are denoted by the same reference numerals. In chemical substance concentrator  40  shown in  FIG. 7 , inlet  16  of flow passage  13  may be provided above adsorption part  12 . In other words, fibers  15  of adsorption part  12  extend perpendicularly from surface  14 A toward inlet  16 . Thus, flow direction D 40  in which the sample flows has a component directed from end  12 A to end  12 B of adsorption part  12 , and inclines with respect to adsorption part  12 . 
       FIG. 8  is a side cross-sectional view of further chemical substance concentrator  40 A in accordance with the embodiment. In  FIG. 8 , components identical to those of chemical substance concentrator  40  shown in  FIG. 7  are denoted by the same reference numerals. In chemical substance concentrator  40 A shown in  FIG. 8 , flow passage  13  of inlet  16  inclines at an angle with respect to adsorption part  12 . In other words, inlet  16  is provided above a portion of inner surface  11 A having adsorption part  12  thereon closer to inlet  16 . Adsorption part  12  may incline relatively with respect to flow passage  13 . Thus, flow direction D 40 A in which the sample flows has a component directed from end  12 A to end  12 B of adsorption part  12 , and inclines with respect to adsorption part  12 . 
     Accordingly, the sample can enter between fibers  15  of adsorption part  12 . Chemical substance concentrators  40  and  40 A can adsorb chemical molecules efficiently. 
     As mentioned above, chemical substance concentrator  10  ( 10 A to  10 H,  30 ,  30 A,  40 , and  40 A) includes tubular body  11  and adsorption parts  12  provided in an inside of tubular body  11 . Tubular body  11  forms flow passage  13  through which sample A 10  containing a chemical substance flows in flow direction D 10 . Adsorption parts  12  adsorb the chemical substance, and desorb the adsorbed chemical substance. Adsorption part  12  is an aggregation of fibers  15  made of metal oxide. In the cross section of tubular body  11  perpendicular to flow direction D 10 , adsorption parts  12  are arranged to be spaced from one another by interval B 1 . 
     In the cross section of tubular body  11 , interval B 1  between adsorption parts  12  adjacent to each other among adsorption parts  12  may be larger than interval D 1  between fibers  15  in adsorption part  12 . 
     Tubular body  11  may have inner surface  11 A on which adsorption parts  12  are provided, and inner surface  11 B that faces inner surface  11 A of tubular body  11  and is separated from adsorption parts  12 . 
     End  12 A of adsorption part  12  may be located more downstream in flow direction D 10  than end  12 B. 
     Fibers  15  may be made of ZnO. 
     Desorption part  94  desorbs, from adsorption parts  12 , the chemical substance adsorbed on adsorption parts  12 . 
     Desorption part  94  may be heating unit  14  for heating adsorption parts  12 . 
     Desorption part  94  may be vibrator  24  for vibrating adsorption parts  12 . 
     Desorption part  94  may be light irradiation unit  34  for irradiating adsorption parts  12  with light. 
     Adsorption parts  12  may be arranged meanderingly. 
     Adsorption parts  12  may be arranged in a row. 
     Adsorption parts  12  may be arranged in a row without an interval in a cross section of tubular body  11  other than the above-mentioned cross section. 
     Adsorption parts  12  may desorb the adsorbed chemical substance into sample A 10 . 
     Chemical substance concentrators  10 ,  10 A to  10 H,  30 ,  30 A,  40 , and  40 A may be formed inside a pipe provided in a detection system, for example. In this case, the pipe of the detection system serves as tubular body  11 . 
     As mentioned above, a chemical substance concentrator according to one or more aspects has been described based on the exemplary embodiments, the present disclosure is not limited to the exemplary embodiments. Forms obtained by various modifications to the exemplary embodiments that can be conceived by a person of skill in the art as well as forms realized by combining structural components in different exemplary embodiments, which are within the scope of the essence of the present disclosure, may be included in the one or more aspects. 
     REFERENCE MARKS IN THE DRAWINGS 
     
         
           10 ,  10 A- 10 H,  30 ,  30 A,  40 ,  40 A chemical substance concentrator 
         tubular body 
           11 A inner surface (first inner surface) 
           11 B inner surface (second inner surface) 
           12  adsorption part 
           12 A end (first end) 
           12 B end (second end) 
           13  flow passage 
           14  heating unit 
           15  fiber 
           16  inlet 
           17  outlet 
           18  power source 
           94  desorption part