# Patent

## Title
Biochemical analyzer and method of controlling internal temperature of the biochemical analyzer

## Abstract

Provided is a biochemical analyzer including: a microfluidic device loading space including a microfluidic device supporting unit detachably supporting a microfluidic device including an electromagnetic radiation application region in which electromagnetic energy is applied; an energy source loading space including an energy source applying the electromagnetic energy to the electromagnetic radiation application region; and an isolation wall isolating the microfluidic device loading space and the energy source loading space to prevent heat transfer between the microfluidic device loading space and the energy source loading space and including a transparent window through which the electromagnetic energy can be transmitted. A method of controlling an internal temperature of the biochemical analyzer is also provided.

## Background
CROSS-REFERENCE TO RELATED PATENT APPLICATION
This is a Division of application Ser. No. 11/972,708, filed Jan. 11, 2008, which claims priority from Korean Patent Application No. 10-2007-0072488, filed on Jul. 19, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of biochemistry, and more particularly, to a biochemical analyzer capable of performing various assays using biological samples and a method of controlling the internal temperature of the biochemical analyzer.
2. Description of the Related Art
Recently, a biochemical assay technique diagnosing a specific disease or detecting the presence of a specific component using a trace amount of a fluid sample such as blood or urine is advancing. A microfluidic device that is used in a biochemical assay using a trace amount of a fluid generally includes a chamber containing the fluid, a channel through which the fluid flows, and a valve controlling the flow of the fluid. A device in which an assay including a biochemical reaction is performed on a microchip is called a “biochip”. In particular, a device designed for performing various steps of fluid treatments and manipulations on a single chip is called a “lab-on-a-chip”.
In order to move a fluid in a microfluidic device, a driving pressure is required. The driving pressure may be a capillary pressure or a pressure exerted by a separate pump. Disk type microfluidic devices including a chamber and a channel have recently been proposed, and a fluid movement is caused by a centrifugal force generated by rotating the disk type microfluidic devices. These disk type microfluidic devices are also called as “Lab CDs” or “Lab-on-a-CDs”.
An apparatus configured to provide atmospheric conditions suitable for a measurable biological sample reaction and to detect the reaction results is designated as a “biochemical analyzer”. Meanwhile, in some cases, in order to perform a reaction such as a lysis reaction or to open or close a valve controlling a fluid flow, electromagnetic radiation such as laser should be applied to a microfluidic device. For the electromagnetic radiation application, a biochemical analyzer should include an energy source including a laser diode (LD), etc.
FIGS. 1A and 1B are graphs illustrating the characteristics of a laser diode, specifically the characteristics of a model Sony SLD 323V which is a laser diode. Referring to FIGS. 1A and 1B, as an external temperature (Tc) increases, the optical intensity and wavelength of the laser diode increase. In most other laser diodes, in addition to the model Sony SLD 323V, an optimal optical intensity and wavelength for performing a biochemical reaction using a biological sample are achieved at about 25° C.
However, optimal results for a biochemical reaction using a biological sample are achieved at about 37° C. which is similar to the normal body temperature of most people. As such, since the optimal temperature condition of an energy source is different from the optimal temperature condition of a biochemical reaction using a biological sample, the reliability of various assays using a biochemical analyzer is lowered, and energy consumption for the assays is increased.
SUMMARY OF THE INVENTION
The present invention provides a biochemical analyzer that can simultaneously satisfy the optimal temperature condition of an energy source and the optimal temperature condition for a biochemical reaction using a biological sample, and a method of controlling the internal temperature of the biochemical analyzer.
According to an aspect of the present invention, there is provided a biochemical analyzer including: a microfluidic device loading space including a microfluidic device supporting unit detachably supporting a microfluidic device including an electromagnetic radiation application region in which electromagnetic energy is applied; an energy source loading space including an energy source applying the electromagnetic energy to the electromagnetic radiation application region; and an isolation wall isolating the microfluidic device loading space and the energy source loading space to prevent heat transfer between the microfluidic device loading space and the energy source loading space and including a transparent window through which the electromagnetic energy can be transmitted.
The microfluidic device supporting unit may include a motor rotating the microfluidic device.
The energy source may include a laser diode (LD).
The biochemical analyzer may further include an energy source movement unit horizontally moving the energy source.
The microfluidic device loading space may further include a heater for heating the microfluidic device.
The microfluidic device loading space may further include a first temperature sensor for measuring a temperature of the microfluidic device loading space, and if a temperature measured by the first temperature sensor is lower than a first reference temperature, the heater may be operated.
The first reference temperature may be 37° C.
The biochemical analyzer may further includes a first cooler for cooling the temperature of the microfluidic device loading space, and if the temperature measured by the first temperature sensor is higher than the first reference temperature, the first cooler may be operated.
The first cooler may include an inlet fan for inducing external air to flow into the microfluidic device loading space.
The first cooler may further include a filter for filtering particles contained in the external air entering into the microfluidic device loading space.
The biochemical analyzer may further include a second cooler for cooling the temperature of the energy source loading space.
The energy source loading space may further include a second temperature sensor for measuring the temperature of the energy source loading space, and if a temperature measured by the second temperature sensor is higher than a second reference temperature, the second cooler may be operated.
The second cooler may include an energy source cooling fan for cooling the energy source by inducing external air to flow into the energy source loading space.
The second cooler may include an energy source cooling duct for guiding the external air into the energy source.
The second reference temperature may be 25° C.
The isolation wall except at least the transparent window may be formed of plastic.
The transparent window may be formed of glass, crystal, or plastic.
Anti-reflect coating may be applied to a surface of the transparent window.
According to another aspect of the present invention, there is provided a method of controlling an internal temperature of the biochemical analyzer. The method includes measuring a temperature of the microfluidic device loading space using the first temperature sensor and operating the heater if the measured temperature is lower than a first reference temperature. The method includes measuring the temperature of the energy source loading space using the second temperature sensor and operating the second cooler if the measured temperature is higher than a second reference temperature. This can be achieved by a temperature control method obvious to one of ordinary skill in the art, e.g., a PID control technique.
In the method of controlling the internal temperature of the biochemical analyzer, if the temperature measured by the first temperature sensor is higher than the first reference temperature, the first cooler may be operated. This can be achieved by a temperature control method obvious to one of ordinary skill in the art, e.g., a PID control technique.
According to a biochemical analyzer of the present invention, the optimal temperature condition of an energy source and the optimal temperature condition for a biochemical reaction using a biological sample can be satisfied at the same time even though the two conditions are different. Therefore, the reliability of various assays using a biochemical analyzer can be enhanced, and energy consumption for the assays can be reduced.



BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
FIGS. 1A and 1B are graphs illustrating the characteristics of a laser diode;
FIG. 2 is a schematic sectional view illustrating a biochemical analyzer according to an exemplary embodiment of the present invention;
FIG. 3 is a plan view illustrating an example of a microfluidic device which can be loaded in the biochemical analyzer of FIG. 2;
FIG. 4 is a plan view illustrating the inside of an energy source loading space of FIG. 2; and
FIG. 5 is an exploded perspective view illustrating an inlet duct of FIG. 2.



DETAILED DESCRIPTION OF THE INVENTION
A biochemical analyzer and a method of controlling the internal temperature of the biochemical analyzer according to the present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.
FIG. 2 is a schematic sectional view illustrating a biochemical analyzer according to an exemplary embodiment of the present invention, FIG. 3 is a plan view illustrating an example of a microfluidic device which can be loaded in the biochemical analyzer of FIG. 2, FIG. 4 is a plan view illustrating the inside of an energy source loading space of FIG. 2, and FIG. 5 is an exploded perspective view illustrating an inlet duct of FIG. 2.
Referring to FIG. 2, a biochemical analyzer 100 according to an exemplary embodiment of the present invention includes, in a case 101, a microfluidic device loading space 110, an energy source loading space 140, and an isolation wall 160 isolating the two spaces 110 and 140. The microfluidic loading space 110 includes a microfluidic device supporting unit for detachably supporting a microfluidic device 10. The case 101 includes an input unit 105 including buttons for inputting a command, etc., a display unit including an LCD panel for displaying an operating state of the biochemical analyzer 100, etc., and a front door 103.
Referring to FIG. 3, the microfluidic device 10 is structured such that a specific reaction using a biological sample (e.g., blood) can be performed in a disk type platform. The microfluidic device 10 includes a chamber 15 for containing a fluid, a channel 12 for providing the path of the fluid, and a valve 17 for controlling the flow of the fluid in the channel 12. A center portion of the microfluidic device 10 includes a spindle insertion hole 11 for inserting a spindle 113 (see FIG. 2) as will be described later.
The microfluidic device 10 may be formed of a plastic material which has good formability, is optically transparent, and has a biologically inactive surface, e.g., PMMA (polymethyl methacrylate), PDMS (polydimethylsiloxane), or PC (polycarbonate). However, a material of the microfluidic device 10 is not limited to the above-described examples provided that it is a material having chemical and biological stability, optical transparency, and mechanical processability. The platform of the microfluidic device 10 may be formed of multi-layered plates. A space and a path respectively corresponding to the chamber 15 and the channel 12 can be provided in the platform by forming engraved structures corresponding to the chamber 15 and the channel 12 in facing surfaces of plates and joining the plates. The joining of the plates can be achieved by various methods such as adhesion using an adhesive or a double coated tape, ultrasonic fusion, laser welding, or adhesion using a UV adhesive.
In order to perform a specific reaction such as a lysis reaction, electromagnetic radiation such as laser should be applied to cells in a sample. In this case, the chamber 15 wherein the specific reaction occurs serves as an electromagnetic radiation application region wherein electromagnetic energy is applied. On the other hand, when the valve 17 is formed of a composition including a phase transition material and a plurality of metal oxide particles, the channel 12 can be opened by applying electromagnetic radiation (e.g., laser) to the valve 17. In this case, the valve 17 serves as an electromagnetic radiation application region wherein electromagnetic energy is applied.
Referring again to FIG. 2, the microfluidic device supporting unit included in the microfluidic device loading space 110 includes the spindle 113 inserted into the spindle insertion hole 11 (see FIG. 3), a microfluidic device driving motor 112 rotating the microfluidic device 10 by rotating the spindle 113, and a clamp 114 pressing the microfluidic device 10 inserted into the spindle 113 to prevent the separation of the microfluidic device 10 from the spindle 113. The clamp 114 can be fastened to the isolation wall 160.
The spindle 113 is constrictedly moved toward the microfluidic device driving motor 112, as shown by a double dashed line. The microfluidic device driving motor 112 is horizontally reciprocally moved so that it can be moved out of the front door 103 of the case 101. When an appropriate input is input into the input unit 105, the front door 103 is opened and the microfluidic device driving motor 112 is moved out of the case 101 in a state wherein the spindle 113 is constricted toward the microfluidic device driving motor 112, thereby enabling easy insertion of the microfluidic device 10 into the spindle 113. Then, when another appropriate input is input into the input unit 105, the microfluidic device driving motor 112 is returned to the microfluidic device loading space 110, the spindle 113 is moved upward and connected to the clamp 114 so that the microfluidic device 10 is not separated from but is fastened to the spindle 113, and the front door 103 is closed. While the spindle 113 is rotated, a centrifugal force is exerted to the microfluidic device 10. The centrifugal force may be at least one of external conditions for inducing a specific reaction in a sample contained in the microfluidic device 10. In the embodiment shown in FIGS. 2 and 3, the microfluidic device 10 has a disk shape, and the spindle 113 connected to the microfluidic device driving motor 112 rotatably supports the microfluidic device 10. However, the present invention is not limited thereto. For example, a biochemical analyzer including a table simply supporting a chip type microfluidic device is also within the scope of the present invention.
The microfluidic device loading space 110 includes a heater 115 for heating the microfluidic device 10. In order to efficiently heat the microfluidic device 10, the heater 115 is disposed to be close to the upper and lower surfaces of the microfluidic device 10. The heater 115 may be any of various types of heaters, e.g., a resistor or a halogen lamp. In the microfluidic device loading space 110, a first temperature sensor 117 for measuring the internal temperature of the microfluidic device loading space 110 is disposed adjacent to the microfluidic device 10. The embodiment shown in FIGS. 2 and 3 illustrates that the heater 115 and the first temperature sensor 117 are disposed adjacent to the microfluidic device 10. However, the present invention is not limited thereto provided that the heater 115 and the first temperature sensor 117 are structured such that the microfluidic device loading space 110 is heated and the internal temperature of the microfluidic device loading space 110 can be measured.
The biochemical analyzer 100 includes a first cooler 120 for cooling the inside of the microfluidic device loading space 110. The first cooler 120 includes an inlet fan 129 for forcibly inducing external air to flow into the microfluidic device loading space 110, and an inlet duct 121 for guiding the external air into the microfluidic device loading space 110. The first cooler 120 also includes an outlet fan 135 for forcibly discharging air from the microfluidic device loading space 110 and an outlet duct 131 for guiding the internal air outward. FIG. 2 illustrates that the first cooler 120 includes the inlet fan 129 and the outlet fan 135, but the present invention is not limited thereto. For example, a biochemical analyzer in which a thermoelectric cooler is included in a microfluidic device loading space is also within the scope of the present invention.
Referring to FIG. 5, the inlet duct 121 includes a filter 122 for filtering particles (e.g., dust) included in external air entering into the microfluidic device loading space 110 (see FIG. 2). The filter 122 is received in a filter case 123 having slits 124 and inserted into the inlet duct 121. In order to prevent the separation of the filter 122 from the inlet duct 121, a detachable cap 125 is provided at an entrance of the inlet duct 121. External air enters into the inlet duct 121 via slits 126 formed in the cap 125.
The microfluidic device loading space 110 includes an optical detector 138 for determining the presence and amount of a predetermined component by optically detecting a reaction occurred in a sample of the microfluidic device 10. The optical detector 138 determines the presence and amount of a predetermined component by measuring the absorbance or fluorescence intensity of a product of the reaction occurred in the sample contained in the chamber 15 (see FIG. 3).
The energy source loading space 140 includes an energy source 145 applying electromagnetic energy to an electromagnetic radiation application region of the microfluidic device 10. The energy source 145 includes a laser diode 146 applying laser L, which is a kind of electromagnetic radiation, to the microfluidic device 10 and a heat sink 149 for heat radiation. A second temperature sensor 147 (see FIG. 4) for measuring the internal temperature of the energy source loading space 140 is disposed in the energy source 145.
The biochemical analyzer 100 further includes an energy source movement unit for horizontally moving the energy source 145 along a lengthwise direction of a transparent window 162 formed in the isolation wall 160. Referring to FIG. 4, the energy source movement unit includes an energy source movement motor 155 and a helical shaft 152 coaxially connected to a shaft of the energy source moving motor 155. The helical shaft 152 includes a helical gear, and thus, is engaged with the energy source 145. Thus, the energy source 145 can be reciprocally moved in the lengthwise direction of the transparent window 162 according to the rotation direction of the helical shaft 152.
Referring again to FIG. 2, the biochemical analyzer 100 includes a second cooler 150 for cooling the inside of the energy source loading space 140. The second cooler 150 includes an energy source cooling fan 151 for inducing external air to flow into the energy source loading space 140 and an energy source cooling duct 153 which extends to be close to the energy source 145 and guides the external air into the energy source 145. FIG. 2 illustrates that the second cooler 150 includes the energy source cooling fan 151, but the present invention is not limited thereto. For example, a biochemical analyzer wherein a thermoelectric cooler is included in an energy source loading space is also within the scope of the present invention.
The isolation wall 160 (except for at least the transparent window 162) isolating the microfluidic device loading space 110 and the energy source loading space 140 may be formed of a plastic which prevents heat transfer between the two spaces 110 and 140 and which is inexpensive. The transparent window 162 may be formed of glass, crystal, or plastic which is transparent with respect to the laser L emitted from the laser diode 146. According to an exemplary embodiment of the present invention, anti-reflect coating may be applied to a surface of the transparent window 162 in order to enhance transparency.
The biochemical analyzer 100 includes a main circuit board 142. The main circuit board 142 functions to control the internal temperature of the biochemical analyzer 100, to control the driving of the motors 112 and 150 and the light emission of the laser diode 146, and to assay a sample reaction using the optical detector 138.
Hereinafter, a method of controlling the internal temperature of the biochemical analyzer 100 will be described with reference to FIG. 2. The temperature of the microfluidic device loading space 110 and the temperature of the energy source loading space 140 are independently controlled. A temperature control of the microfluidic device loading space 110 is performed as follows. While the biochemical analyzer 100 is operated, the temperature of the microfluidic device loading space 110 is periodically measured using the first temperature sensor 117. If the measured temperature is lower than a first reference temperature, the heater 115 is operated to increase the temperature of the microfluidic device loading space 110.
According to an exemplary embodiment of the present invention, the first reference temperature may be 37° C. which is known to be a temperature at which an optimal reaction result using a biological sample is achieved. Meanwhile, if a temperature measured by the first temperature sensor 117 is higher than the first reference temperature, the operation of the heater 115 is stopped, and the inlet and outlet fans 129 and 135 of the first cooler 120 are operated to lower the temperature of the microfluidic device loading space 110.
A temperature control of the energy source loading space 140 is performed as follows. While the biochemical analyzer 100 is operated, the temperature of the energy source loading space 140 is periodically measured using the second temperature sensor 147 (see FIG. 4). If the measured temperature is higher than a second reference temperature, the cooling fan 151 of the second cooler 150 is operated to lower the temperature of the energy source loading space 140. This can be achieved by a temperature control method obvious to one of ordinary skill in the art, e.g., a PID control technique.
According to an exemplary embodiment of the present invention, the second reference temperature may be 25° C. which is known to be a temperature at which light emitted from the laser diode 146 has an optimal optical intensity and wavelength.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

## Claims

1. A method of controlling an internal temperature of a biochemical analyzer comprising: a microfluidic device loading space which receives a microfluidic device, the microfluidic device loading space comprising a microfluidic device supporting unit detachably supporting the microfluidic device; an energy source loading space which receives an energy source, the energy source applying the energy to the microfluidic device; an isolation wall isolating the microfluidic device loading space from the energy source loading space to prevent heat transfer between the microfluidic device loading space and the energy source loading space, the isolation wall comprising a window through which the energy can be transmitted; a heater which heats the microfluidic device; and a first temperature sensor which measures a temperature of the microfluidic device loading space, the method comprising:
measuring the temperature of the microfluidic device loading space using the first temperature sensor; and
operating the heater if the measured temperature is lower than a first reference temperature.

2. The method of claim 1, wherein the first reference temperature is from about 36° C. to about 38° C.

3. The method of claim 1, wherein the biochemical analyzer further comprises a first cooler for lowering the temperature of the inside of the microfluidic device loading space, and
wherein the first cooler is operated, if the temperature measured by the first temperature sensor is higher than the first reference temperature.

4. The method of claim 1, wherein the biochemical analyzer further comprises a second temperature sensor for measuring the temperature of the energy source loading space and a second cooler for lowering the temperature of the inside of the energy source loading space, and
wherein the temperature of the energy source loading space is measured by the second temperature sensor, and, the second cooler is operated, if the measured temperature is higher than a second reference temperature.

5. The method of claim 4, wherein the second reference temperature is from about 24° C. to about 26° C.