SAW sensor module

Abstract

The present invention relates to a SAW sensor module comprising a cartridge including a sensor chip made of a piezoelectric material and at least one SAW sensor formed on the sensor chip, and at least one drive control and readout device for at least one SAW sensor. According to the present invention, the drive control and readout device has a device substrate, a device coupling electrode formed on the front surface of the device substrate, the device coupling electrode is connected to a device terminal formed on the device substrate via an electrical conductor drawn through the device substrate, the cartridge has a cartridge coupling electrode capacitively coupled on one side to the device coupling electrode and on the other side to the sensor electrode of at least one SAW sensor, at least one magnetic element formed on the device substrate, and the cartridge has at least one metal alignment element and / or magnetic alignment element for alignment at at least one magnetic element.

Description

Technical Field

[0001] The present invention relates to a SAW sensor module including a sensor chip made of a piezoelectric material and a cartridge including at least one SAW sensor formed on the sensor chip, and at least one drive control and readout device for at least one SAW sensor.

[0002] Surface Acoustic Wave (SAW) is an elastic surface wave, that is, a solid-borne sound wave that propagates only planar to the surface, that is, only two-dimensionally. The SAW wave penetrates into the material through which it propagates only minimally, and the penetration depth is limited to one wavelength.

[0003] In a SAW sensor, an elastic surface wave is transmitted from a transmitting electrode arranged on the sensor surface to a receiving electrode. In this case, selective receptor layers are arranged on the piezoelectric substrate between the transmitting electrode and the receiving electrode, respectively.

[0004] Preferably, as the transmitter and the receiver, mutually engaging metal comb-shaped structures (so-called comb-shaped interdigital transducers IDT) are used. In this case, an alternating voltage is applied to one of the comb-shaped structures, and the other comb-shaped structure is grounded. As a result, an electric field that periodically changes is generated between the differently charged fingers. In the piezoelectric substrate, the mechanical deformation is caused by the externally applied electric field, so that the substrate alternately expands and contracts.

[0005] In a SAW sensor, two of these IDTs are attached side by side on the sensor substrate. Here, one IDT is used as a transmitter, and the other IDT is used as a receiver. In the transmitter, an alternating voltage signal is converted into an elastic surface wave and transmitted to the substrate. The elastic surface wave causes a movement of charges in the piezoelectric substrate, and this movement of charges forms an alternating voltage signal in the finger structure of the receiver.

[0006] The SAW sensor can be driven as either a delay line or a resonator. In the latter basic configuration, the reflector structure is located outside the IDT.

[0007] Each reflector reflects each incident radio signal as an echo. The time interval between the source signal and the echo, as well as the changes in the magnetic field and phase of each signal, depend, in particular, on the speed of sound, temperature, and mechanical stress in the sensor substrate material used. Furthermore, in the case of SAW sensors based on such reflection, it has been found that the time interval, scale, and phase change depending on the receptor layer deposited on the sensor substrate and bonded to the substrate surface. The resulting mass deposition on the sensor surface causes a change in surface wave velocity. This effect can be used, for example, to determine the specific contents of a fluid in the analysis of biological or chemical samples.

[0008] The object of the present invention is to provide an effective apparatus for easily analyzing chemical and / or biological fluids based on a SAW sensor.

[0009] The above problems are solved by a SAW sensor module according to the present invention, comprising a sensor chip made of piezoelectric material, a cartridge including at least one SAW sensor formed on the sensor chip, and at least one drive control and readout device for the at least one SAW sensor, wherein the drive control and readout device has a device substrate, a device coupling electrode is formed on the front surface of the device substrate, the device coupling electrode is connected to a device terminal formed on the device substrate via an electrical conductor drawn through the device substrate, the cartridge has a cartridge coupling electrode capacitively coupled on one side to the device coupling electrode and on the other side to the sensor electrode of the at least one SAW sensor, at least one magnetic element is formed on the device substrate, and the cartridge has at least one metal alignment element and / or magnetic alignment element for alignment with the at least one magnetic element.

[0010] The SAW sensor module according to the present invention has a variable and continuously usable drive control and readout device, which can be used for multiple measurements. Furthermore, the SAW sensor module according to the present invention has a cartridge that is basically used only once, i.e., used as a disposable component. The SAW sensor component of the cartridge performs sample-dependent measurements of the changes in the generated surface acoustic waves. The drive control and readout of the SAW sensor used here are performed by the drive control and readout device.

[0011] In this invention, signal transmission from the drive control and reading device to the cartridge and from the cartridge to the drive control and reading device is performed simply and with low loss via a capacitive coupling between the drive control and reading device and the cartridge. In this case, two capacitive couplings are used. Specifically, on one hand, a device coupling electrode is positioned opposite the cartridge coupling electrode with a very small gap between them, and on the other hand, the cartridge coupling electrode is capacitively coupled to the sensor electrode via a piezoelectric substrate, thereby easily coupling the capacitive couplings.

[0012] Here, each electrode is directly positioned vertically. In this invention, the alignment of the device coupling electrode with respect to the cartridge coupling electrode is easily achieved by the automatic alignment of the cartridge on the drive control and readout device through magnetic attraction between at least one alignment element and at least one magnetic element. Therefore, the present invention does not require time-consuming adjustments and wiring. On the contrary, simply placing the cartridge on the drive control and readout device will cause it to rotate to the correct position automatically, allowing evaluation to begin. This alignment works in both rotation and translation. After alignment, the cartridge is stably positioned on the drive control and readout device in all axes.

[0013] In a particularly mechanically stable embodiment of the present invention, the cartridge has a support substrate located between the sensor chip and the device substrate, and a cartridge coupling electrode is formed on the support substrate. The support substrate forms a stable base, which is advantageous as the cartridge coupling electrode can be formed on the base, and more advantageously as the sensor chip and another structural part of the cartridge, such as the cartridge housing, can be constructed.

[0014] However, it is also possible to directly capacitively couple the sensor electrodes of the sensor chip with the device coupling electrodes of the device substrate.

[0015] A fluid frame surrounding a fluid pool is constructed on the SAW sensor component, and a cap is formed on the sensor chip to enclose the fluid frame, where the cap and fluid frame cover the sensor electrode and reflector of at least one SAW sensor. In this case, the SAW sensor module according to the present invention can analyze fluid particularly easily and reliably. The fluid pool allows all travel sections or tracks of the SAW sensors to be the same length when the SAW sensor module has multiple SAW sensors, thereby facilitating the formation of differences between the signals of these SAW sensors.

[0016] If the fluid frame is a lever structure that is suspended on one end in a groove formed in the cap and on the other end in pressure against the front surface of the sensor chip, thereby sealing it, then the fluid frame forms a mechanically particularly stable and dense frame surrounding the fluid pool.

[0017] If the fluid frame forms a funnel with an angled wall on at least one SAW sensor, or if such a funnel is placed on the fluid frame, the fluid pool can be filled with fluid particularly easily.

[0018] The cap is preferably a plastic injection-molded member through which at least one alignment element extends. This allows for the production of cartridges in large quantities with high reproducibility, and consequently, at a low cost.

[0019] If the SAW sensor module according to the present invention is not yet in use and a cover film is laminated over the fluid frame, at least one SAW sensor can be protected particularly effectively from external influences.

[0020] If the cartridge has multiple strip-shaped SAW sensors arranged parallel to each other, at least one of these SAW sensors can be used as a reference sensor. For example, the reference sensor can be formed without a selective receptor layer. Furthermore, one of the SAW sensors can be used to compensate for environmental or temperature effects.

[0021] It is significant that the travel sections of the measuring sensor and the reference SAW sensor that come into contact with the fluid to be analyzed are of the same length.

[0022] The SAW sensors are preferably separated from each other by a separation wall located between them.

[0023] If at least two of the SAW sensors have different travel sections, these travel sections can be electrically connected in parallel or in series and read out in common through the combined section. In this case, each signal from the sensors can be separated by an evaluation electronic circuit based on its travel time.

[0024] In another advantageous embodiment of the present invention, each SAW sensor is associated with a separate capacitance terminal. This allows multiple SAW sensors to be measured and evaluated simultaneously, thereby reducing measurement errors.

[0025] It is particularly advantageous that at least one RFID chip is formed on the sensor chip and / or on the support substrate, connected to the device terminal via at least one capacitive coupling portion. By using the RFID chip, the cartridge and the fluid sample determination performed within the cartridge can be uniquely identified, and the detected measurement values ​​can be associated accordingly. Here, data transmission is easily performed via at least one capacitive coupling portion.

[0026] When a dielectric protective film is disposed between the cartridge and the drive control and reading device, for example, advantageous protection of the drive control and reading device against dirt or moisture is achieved. Such a protective film functions as a dielectric for the capacitive coupling portion between the drive control and reading device and the cartridge, and the capacitive coupling portion is not impaired.

[0027] Hereinafter, preferred embodiments, structures, functions, and advantages of the present invention will be described in detail with reference to the drawings.

Brief Description of the Drawings

[0028] [Figure 1] FIG. 1 is a plan view schematically showing an embodiment of a SAW sensor module according to the present invention. [Figure 2] FIG. 2 is a plan view schematically showing a device substrate of the SAW sensor module of FIG. 1. [Figure 3] FIG. 3 is a side sectional view schematically showing an embodiment of a SAW sensor module according to the present invention. [Figure 4] FIG. 4 is a side sectional view schematically showing a portion of a sensor chip, a cap, and a fluid pool of an embodiment of a SAW sensor module according to the present invention. [Figure 5] FIG. 5 is a plan view schematically showing a SAW sensor of an embodiment of a SAW sensor module according to the present invention.

[0029] In FIG. 1, an embodiment of a SAW sensor module 1 according to the present invention is schematically shown in a plan view. In FIG. 1, the hidden structure of the SAW sensor module 1 is shown in gray. In FIG. 3, an embodiment of a SAW sensor module 1 according to the present invention is schematically shown in a side sectional view.

[0030] The SAW sensor module 1 has a drive control and readout device 4 equipped with a device substrate 40 schematically shown in Figure 3, the device substrate 40 of which is individually shown in a plan view in Figure 2. The device substrate 40 is a non-conductive circuit board with a conductive structure formed on its upper surface. The device substrate 40 has two device coupling electrodes 43, 44 on the device substrate surface 41 shown in Figure 2, and these two device coupling electrodes 43, 44 are formed in an annular shape in the illustrated embodiment, but can have other shapes.

[0031] The device coupling electrodes 43 and 44 are connected to the device electrical terminals 47 on the rear surface 42 of the device substrate via electrical conductors 45 and 46 that are drawn out through the device substrate 40.

[0032] Furthermore, the device substrate 40 has two magnetic elements 51, 52, which are accessible via the front surface 41 of the device substrate. In another embodiment of the present invention, only one magnetic element may be formed on the front surface 41 of the device substrate, or three or more magnetic elements 51, 52 may be formed thereon.

[0033] A cartridge 2, which may also be called a casing, is mounted on the drive control and reading device 4. While the drive control and reading device 4 is designed for continuous use, the cartridge 2 is designed for single use, i.e., as a disposable component. A dielectric protective film 8, such as Kapton tape, is placed between the drive control and reading device 4 and the cartridge 2.

[0034] Cartridge 2 has a SAW sensor component 3. In the illustrated embodiment, the SAW sensor component 3 has a support substrate 20 and a sensor chip 30 having at least one SAW sensor 33, preferably a plurality of SAW sensors 33, 34, 35 disposed on the support substrate 20. In another embodiment of the present invention not shown, the SAW sensor component 3 may have only a single substrate integrating the elements of the support substrate 20 and the elements of the sensor chip 30 as described below.

[0035] The support substrate 20 has cartridge coupling electrodes 23 and 24 on its rear surface 27, opposite to the device coupling electrodes 43 and 44. In the illustrated embodiment, the device coupling electrodes 43 and 44 have a larger diameter than the rear-side cartridge coupling electrodes 23 and 24. The device coupling electrodes 43 and 44 and the rear-side cartridge coupling electrodes 23 and 24 formed on the rear surface of the cartridge 2 may be formed concentrically with each other, but this is not necessarily required.

[0036] Only a dielectric protective film 8 is located between the rear-side cartridge coupling electrodes 23, 24 and the device coupling electrodes 43, 44. Since the drive control and readout device 4 must be sterilized periodically, the dielectric protective film 8 can provide both advantageous protection against disinfectants and advantageous protection against dirt and general moisture. The rear-side cartridge coupling electrodes 23, 24 and the device coupling electrodes 43, 44 are capacitively coupled, rather than being connected via an electrical conductor.

[0037] The front surface 28 of the support substrate 20 is provided with front cartridge coupling electrodes 25 and 26, and these cartridge coupling electrodes 25 and 26 are electrically connected to rear cartridge coupling electrodes 23 and 24 via electrical conductors 48 and 49 that are drawn out through the support substrate 20.

[0038] In the illustrated embodiment, the support substrate 20 is made of a non-conductive material and is a circuit board on which a conductive structure is formed. The support substrate 20 is used to form a capacitive coupling between the sensor chip 30 of the cartridge 2 and the drive control and readout device 4. Furthermore, the support substrate 20 has a support function by supporting the sensor chip 30. Further adaptation elements for output adaptation, such as coils and / or capacitors, can be provided on the support substrate 20.

[0039] Furthermore, the support substrate 20 may have markings that can be used to place the sensor chip 30 on the support substrate 20.

[0040] In the support substrate 20, the electrical connection between the electrical contact or electrode on the surface 28 of the support substrate and the rear surface 27 of the support substrate can be configured arbitrarily. This provides mechanical and electrical degrees of freedom.

[0041] The sensor chip 30 is made of a piezoelectric material. The sensor chip 30 has at least one SAW sensor 33 on its front surface 37. The at least one SAW sensor 33 is driven by sensor electrodes 31, 32, which are also located on the front surface 37 of the sensor chip.

[0042] The sensor electrodes 31 and 32 are capacitively coupled to the cartridge coupling terminals 25 and 26 on the front. In this case, the piezoelectric material of the sensor chip 30 forms the dielectric of the capacitive coupling device.

[0043] Typically, the sensor chip 30 is bonded to the support substrate 20. In this case, the adhesive used forms part of the dielectric material described above.

[0044] Therefore, the sensor electrodes 31 and 32 are connected to the device terminal 47 of the drive control and readout device 4 via the front cartridge coupling electrodes 25 and 26, the rear cartridge coupling electrodes 23 and 24, and the device coupling electrodes 43 and 44, thereby making at least one SAW sensor 33 electrically contactable and readable.

[0045] A fluid pool 70 is formed in the cartridge 2 above at least one SAW sensor 33. The fluid pool 70 is laterally defined by a fluid frame 7.

[0046] The fluid frame 7 can be formed by an inclined wall, for example, as schematically shown in Figure 4, which forms a funnel on the sensor tip 30 above at least one SAW sensor 33. In this case, as seen in Figure 4, the inclined wall can be formed in the form of a lever, which is suspended on one side within a groove 72 of a cap 71 surrounding the fluid pool 70 and on the other side resting on the sensor tip 30, sealed by a seal 75. The seal 75 may be, for example, an adhesive bead.

[0047] In the illustrated embodiment, the cap 71 is formed as a plastic injection molded member.

[0048] The cap 71, together with the fluid frame 7, covers the sensor electrodes 31, 32 and reflector of at least one SAW sensor 33.

[0049] The fluid to be detected can be introduced into the fluid pool 70. The size of the fluid pool 70 determines the volume of fluid that can be analyzed. The molecules of the fluid in this fluid can bond to the surface of at least one SAW sensor 33, which changes the surface wave waveguide characteristics of that surface, and thus the corresponding fluid can be detected.

[0050] The fluid pool 70 is covered by a cover film 9 when cartridge 2 is not in use. The cover film 9 is removable.

[0051] In the illustrated embodiment, at least one RFID chip 10 is arranged on the sensor chip 30. The RFID chip 10 is further capacitively coupled to the cartridge coupling electrode of the support substrate 2 via the sensor chip 30, and further capacitively coupled to the device coupling electrode of the device substrate 40 via the cartridge coupling electrode. By using the RFID chip 10, the cartridge 2 and the fluid sample determination performed within the cartridge 2 can be uniquely distinguished, and consequently, the detected measurement values ​​can be associated with each other. In another embodiment of the present invention, the RFID chip 10 may be arranged on the support substrate 20.

[0052] Preferably, the RFID chip 10 is a semiconductor-based RFID chip rather than a SAW-based one. The RFID chip 10 can store, for example, information that is being performed by the SAW sensor module 1 for testing at that time. It is also possible to read from the RFID chip 10 whether the SAW sensor module 1 is already in use. Furthermore, batch numbers, expiration dates, etc., can also be stored in the RFID chip 10.

[0053] In the illustrated embodiment, three SAW sensors 33, 34, and 35 are formed on the sensor chip 30. As schematically shown in Figure 5, the SAW sensors 33, 34, and 35 each have different travel sections L1, L2, and L3. Therefore, the signals from the SAW sensors 33, 34, and 35 can be distinguished from each other well.

[0054] In the illustrated embodiment, the SAW sensors 33, 34, and 35 are 300 MHz SAW sensors, but other frequency-based SAW sensors may also be used. The SAW sensors 33, 34, and 35 are strip-shaped and formed parallel to each other. A fluid pool 70 is located above the central region of the SAW sensors 33, 34, and 35.

[0055] A separation wall 38, formed by photolithography, is provided between the SAW sensors 33, 34, and 35. The separation wall 38 mutually protects both the individual regions of the SAW sensors 33, 34, and 35 and the IDT of the separation wall 38.

[0056] Furthermore, a cover is formed over the area of ​​the sensor chip 30 that is not in contact with the fluid to be analyzed. The cover is formed by photolithography layer patterning.

[0057] In the illustrated embodiment, the SAW sensors 33, 34, and 35 are connected in series, utilizing a single common capacitive coupling electrode pair for contact connection. However, this is not mandatory; for example, the SAW sensors 33, 34, and 35 can be driven and controlled sequentially via a multiplexer for reading. Parallel connection of the individual SAW sensors 33, 34, and 35 is also possible.

[0058] In the embodiment shown in Figure 5, the SAW sensor 33 forms the sample channel, i.e., the original measurement channel; the SAW sensor 34 forms a compensation channel to compensate for temperature effects; and the SAW sensor 35 forms a reference channel, meaning it does not have a selective receptor layer.

[0059] In another embodiment of the present invention, SAW sensors 33, 34, and 35 can be used to measure different analytes, respectively.

[0060] A metal or magnetic alignment element 6 is drawn through the cartridge 2, and in the illustrated embodiment, the alignment element 6 is formed from a metal wire, such as a steel wire. At least one alignment element 6 is advantageously drawn through a pre-formed hole in the cartridge 2, for example, in a corner of the cartridge 2. A magnetic field yoke can also be used as the alignment element 6 instead of a steel wire.

[0061] The ends of the alignment element 6 are terminated on the rear surface 27 of the support substrate facing the magnetic elements 51 and 52. Due to the interaction between the ends of the alignment element 6 and the magnetic elements 51 and 52, when the cartridge 2 is placed on the device substrate 40, the cartridge 2 is automatically aligned on the device substrate 40. Through this automatic alignment, the cartridge coupling electrodes 23 and 24 are automatically positioned on the device coupling electrodes 43 and 44.

Claims

1. The system comprises a cartridge (2) including a sensor chip (30) made of piezoelectric material and at least one SAW sensor (33, 34, 35) formed on the sensor chip (30), and at least one drive control and readout device (4) for the at least one SAW sensor (33, 34, 35). In the SAW observation module (1), The drive control and readout device (4) has a device substrate (40), and device coupling electrodes (43, 44) are formed on the front surface (41) of the device substrate (40), and the device coupling electrodes (43, 44) are connected to device terminals (47) formed on the device substrate (40) via electrical conductors (45, 46) that are drawn out through the device substrate (40). The cartridge (2) has cartridge coupling electrodes (23, 24; 25, 26) which are capacitively coupled on one side to the device coupling electrodes (43, 44) and on the other side to the sensor electrodes (31, 32) of at least one SAW sensor (33, 34, 35), The device substrate (40) has at least one magnetic element (51, 52) formed on it, and the cartridge (2) has at least one metal alignment element and / or magnetic alignment element (6) that aligns with the at least one magnetic element (51, 52). A SAW sensor module (1) characterized by the following features.

2. The SAW sensor module according to claim 1, wherein the cartridge (2) has a support substrate (20) located between the sensor chip (30) and the device substrate (40), and the cartridge coupling electrodes (23, 24; 25, 26) are formed on the support substrate (20).

3. A fluid frame (7) surrounding a fluid pool (70) is formed on the SAW sensor component (3), and a cap (71) is formed on the sensor chip (30) so as to surround the fluid frame (7). The cap (71) and the fluid frame (7) cover the sensor electrodes (31, 32) and the reflector of at least one SAW sensor (33, 34, 35). The SAW sensor module according to claim 1 or 2.

4. The SAW sensor module according to claim 3, wherein the fluid frame (7) is a lever structure that is suspended on one side in a groove (72) formed in the cap (71) and on the other side presses against the front surface (37) of the sensor chip (30) and seals it there.

5. The SAW sensor module according to claim 3 or 4, wherein the fluid frame (7) forms a funnel having an oblique wall on the at least one SAW sensor (33, 34, 35), or the funnel is placed on the fluid frame (7).

6. The SAW sensor module according to any one of claims 3 to 5, wherein the cap (71) is a plastic injection molded member through which the at least one alignment element (6) extends.

7. A SAW sensor module according to any one of claims 3 to 6, wherein a cover film (9) is laminated above the fluid frame (7).

8. The SAW sensor module according to any one of claims 1 to 7, wherein the cartridge (2) has a plurality of SAW sensors (33, 34, 35) arranged in a strip in parallel to each other.

9. The SAW sensor module according to claim 8, wherein a separation wall (38) is formed between the SAW sensors (33, 34, 35).

10. The SAW sensor module according to claim 8 or 9, wherein at least two of the SAW sensors (33, 34, 35) each have different travel sections (L1, L2, L3).

11. A SAW sensor module according to any one of claims 8 to 10, wherein each of the SAW sensors (33, 34, 35) is associated with a separate capacitance terminal.

12. The SAW sensor module according to any one of claims 1 to 11, wherein at least one RFID chip (10) connected to the device terminal (47) via at least one capacitive coupling portion is formed on the sensor chip (30) and / or on the support substrate (20).

13. The SAW sensor module according to any one of claims 1 to 12, wherein a dielectric protective film (8) is disposed between the cartridge (2) and the drive control and readout device (4).

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