CN104037318A - Flexible thermoelectric power generation microcell structure - Google Patents

Abstract

The invention discloses a micro-unit structure for flexible thermoelectric power generation. There are multiple rows and even columns of honeycomb-shaped circular cavities on the base. Except for the two rows of circular cavities on the edge, there is a micropore at the bottom of the other circular cavities, which drips into the bottom of the circular cavity with micropores. Silver-based nanoparticle ink is applied to fill the pores and cover the bottom of the circular cavity. Each row of circular cavities is filled with P-type thermoelectric arms and N-type thermoelectric arms alternately, and the tops of each pair of P-type thermoelectric arms and N-type thermoelectric arms are connected with upper-layer copper wires, and each row has micro-holed N-type thermoelectric arms. The arm and the P-type thermoelectric arm form a group, and the outer bottom surface of the circular cavity with micro-holes is respectively connected with the lower layer of copper wires to form a flexible thermoelectric power generation micro-unit structure. The invention has high flexibility and high stability, and when the thermoelectric power generation unit is impacted, the substrate wrapping the thermoelectric arm can prevent the bismuth telluride thermoelectric material with poor ductility from breaking and failing. It can supply energy for implanted medical micro-device in the body, and has the value of popularization and application.

Description

Micro-unit structure of flexible thermoelectric power generation

technical field

The invention relates to a thermoelectric power generation device, in particular to a flexible thermoelectric microunit structure.

Background technique

Implantable medical devices in the body are used more and more widely, such as pacemakers, defibrillators, drug pumps, etc., which can replace or improve the function of organs or treat certain diseases. Providing durable and stable energy supply for implantable medical devices is a research hotspot and difficult problem in the world today. At present, there are several power sources used in implantable medical devices: lithium batteries, biofuel cells, nuclear batteries, wireless energy transmission, etc. Micro lithium batteries often have a short lifespan, and patients need to replace batteries for a long time, causing a lot of pain; nuclear batteries can work for more than ten years, but they are generally large in size and have toxicity and radiation to the human body; biofuel cells use enzymes or microorganisms As a catalyst, it converts the chemical energy of biofuels such as glucose into electrical energy, but the power supply life is generally only a few days; wireless energy transmission uses electromagnetic waves, electromagnetic coupling, ultrasonic waves, light waves and other wireless transmission methods to charge the implanted power supply in the body or directly Power supply, adopting this method often requires the patient to wear an external additional mechanism for a long time, which brings inconvenience to the patient's daily life and activities.

Thermoelectric power generation uses the Seebeck effect of thermoelectric semiconductors to convert thermal energy into electrical energy. Since the thermoelectric power generation device has the advantages of no moving parts, no pollution, simple structure, and easy miniaturization, etc., at the same time, because the body temperature of the normal human body is constant and there is a small temperature difference between the body and the body surface, the thermoelectric power generation has no requirement for the lower limit of the temperature difference , Therefore, the temperature difference existing in the human body can be used directly to generate electricity.

Existing miniature flexible thermoelectric power generation components usually arrange thermoelectric arms directly on the substrate or use flexible connections between bulk miniature thermoelectric materials, because the internal environment of the human body has many curved surfaces and the human body is flexible, and the thermoelectric arms are often squeezed. Stability of this kind of thermoelectric generator is not enough, so it is necessary to have better flexibility of thermoelectric power generation components; the use of bismuth telluride and its alloys can improve the power generation of thermoelectric power generation devices, but bismuth telluride (BiTe ) The mechanical properties of the material are poor, and the material is relatively brittle. When subjected to pressure or impact, the bismuth telluride and its alloy materials directly processed on the flexible substrate are easy to break, which makes the thermoelectric power generation unit invalid. Therefore, it is very necessary to develop a thermoelectric power generation micro-unit structure that can reduce the impact, is stable, reliable and flexible.

Contents of the invention

The purpose of the present invention is to provide a flexible micro-unit structure for thermoelectric power generation, which has the characteristics of stability and reliability, high thermoelectric conversion efficiency, applicable to curved surfaces, and can be processed into various forms of thermoelectric generators.

The technical scheme adopted in the present invention is:

There are multiple rows and even columns of honeycomb circular cavities on the base. Except for the two rows of circular cavities on the edge, there is a micropore at the bottom of the other circular cavities. The bottom of the circular cavity with micropores drops Silver-based nano-particle ink fills the micropores and covers the bottom of the circular cavity; each row of circular cavity is filled with P-type thermoelectric arms and N-type thermoelectric arms alternately, and each pair of P-type thermoelectric arms and N-type thermoelectric arms The tops of the tops are respectively connected with the upper layer copper wires, and the upper layer copper wires are laid under the upper layer flexible circuit board. Each row of N-type thermoelectric arms and P-type thermoelectric arms with micro-holes is a group, and the outer bottom surface of the circular cavity with micro-holes They are respectively connected with the copper wires of the lower layer, and then the flexible thermoelectric power generation micro-unit structure is sequentially formed in the same connection manner.

The materials of the P-type thermoelectric arm and the N-type thermoelectric arm are both doped bismuth telluride.

Both the base and the upper flexible circuit board are made of polyimide.

The beneficial effects that the present invention has are:

The invention adopts the polyimide honeycomb base to wrap the thermoelectric arm, and the copper wire in the lower layer has a curved structure, so that the thermoelectric power generation unit has high flexibility and can be deformed in multiple directions. When the thermoelectric unit undergoes structural deformation, the circular polyimide cavity wrapping the thermoelectric arm can prevent the bismuth telluride thermoelectric material with poor ductility from breaking and avoid the failure of the thermoelectric unit. The invention is mainly aimed at the energy supply of implanted medical micro-device in the body, and has the value of popularization and application.

Description of drawings

Figure 1 is a frontal isometric view of the structure of the present invention.

Figure 2 is an isometric view of the back of the structure of the present invention.

Fig. 3 is a rear front view of the structure of the present invention.

Fig. 4 is a D-D sectional view of Fig. 3 .

Fig. 5 is a schematic diagram of distribution of P-type and N-type thermoelectric arms.

Fig. 6 is a schematic diagram of the upper flexible circuit board.

Fig. 7 is a front view of the back of the lower flexible circuit board.

Fig. 8 is a sectional view taken along line H-H of Fig. 7 .

Figure 9 is a mold drawing of a honeycomb polyimide substrate.

Figure 10 is a diagram of the mask template required for sputtering the underlying copper wires.

Fig. 11 is a schematic diagram of inkjet printing thermoelectric materials into a circular cavity.

In the figure: 1. Substrate, 2. Silver-based nanoparticle ink, 3. P-type thermoelectric arm, 4. N-type thermoelectric arm, 5. Upper layer flexible circuit board, 6. Upper layer copper wire, 7. Lower layer copper wire, 8. The upper mold of the polyimide base mold, 9, the lower film of the polyimide base mold, 10, the mask plate, 11, the needle head.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 9, the present invention casts polyimide in the lower film 9 of the polyimide base mold, extrudes with the upper mold 8 of the polyimide base mold, and solidifies into the base 1 of the honeycomb circular cavity . As shown in Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 and Fig. 8, the present invention has multiple rows and multiple even-numbered rows of honeycomb circular cavities on the substrate 1 (there are four Arrange four rows of circular cavities, only need to array the two rows in the middle as shown in Figure 2 to increase the number of columns), except for the two rows of circular cavities on the edge, there is a micro-hole at the bottom of the other circular cavities, as shown in Figure 11 , in the circular chamber with micropores in the bottom of the circular chamber with micropores, drop-coat silver-based nanoparticle ink 2 to fill the micropores and cover the bottom of the circular chamber. As shown in Figure 5, each row of circular cavities is evenly filled with P-type thermoelectric arms 3 and N-type thermoelectric arms 4, and the tops of each pair of P-type thermoelectric arms 3 and N-type thermoelectric arms 4 are connected with upper-layer copper wires 6 respectively. The wires are laid under the upper flexible circuit board 5 (as shown in Figure 6). Each row of P-type thermoelectric arms 3 and N-type thermoelectric arms 4 with micro-holes is a group, and the outer bottom surface of the circular cavity with micro-holes is respectively The lower-layer copper wires 7 are used to connect, and then the flexible thermoelectric power generation micro-unit structure is sequentially formed in the same connection manner.

The materials of the P-type thermoelectric arm 3 and the N-type thermoelectric arm 4 are both doped bismuth telluride.

Both the base 1 and the upper flexible circuit board 5 are made of polyimide.

Drop-coating silver-based nanoparticle ink 2 fills the micropores and covers the bottom of the circular cavity, as shown in Figure 5. Filling the P-type thermoelectric arm 3 and the N-type thermoelectric arm 4 with the drop-coating method in each circular cavity, each row The tops of every pair of P-type thermoelectric arms 3 and N-type thermoelectric arms 4 are connected with sputtered upper-layer copper wires 6, and the back sides of each pair of P-type thermoelectric arms 3 and N-type thermoelectric arms 4 with micro-holes are used as shown in Figure 10. The lower-layer copper wire 7 sputtered by the mask plate shown is connected, and the silver-based nanoparticle ink 2 is connected to the lower-layer copper wire 7, so that the bottom end of the wrapped N-type thermoelectric arm 4 is connected to the bottom of the adjacent P-type thermoelectric arm 3 The ends are turned on, and the flexible thermoelectric power generation micro-unit structure is sequentially formed in the same connection mode. The protruding end of the upper flexible circuit board 5 is connected to the external circuit.

The material of the thermoelectric arms is doped bismuth telluride and its alloys, the P-type thermoelectric arms 3 and the N-type thermoelectric arms 4 are alternately arranged, and the honeycomb polyimide substrate can make the device fully flexible.

The micro-unit structure of flexible thermoelectric power generation can be bent into the desired shape, and then a thermoelectric power generation device with high energy density can be formed by packaging composite films and other thermally conductive and insulating flexible materials.

The process of filling micropores and thermoelectric materials is a drop coating method as shown in Figure 11: the needle 11 of the dispenser first drops the silver-based nanoparticle ink into the micropores and covers the bottom of the circular cavity, and then sprays the silver-based nanoparticle ink on the bottom of each row of circular cavities. The P-type thermoelectric material powder and binder and the N-type thermoelectric material powder and binder are dropped into the middle phase, and solidified and formed at room temperature. The processing technology of the upper flexible circuit board: Lay the upper layer of copper wire 6 on the base of the upper layer of flexible circuit board by screen printing method, and the lower layer of copper wire can be obtained by sputtering with a mask plate as shown in Figure 10: apply positive light on the back of the substrate The resist is exposed and developed with a copper mask 10, the copper target is used to sputter the wire pattern, and the glue is removed to complete the copper wire. Each row of P-type thermoelectric arms and N-type thermoelectric arms are arranged alternately, forming thermocouples parallel to each other. The material and structure of the flexible thermoelectric power generation device are highly flexible and can fit curved surfaces.

The working principle of the present invention is:

Due to the Seebeck effect, the temperature difference between the P-type and N-type thermoelectric arms will generate a voltage difference at both ends. Since the voltage generated by a single thermocouple is very low, the method of "parallel connection of thermal circuits and series connection of circuits" can be used to connect P The thermocouples composed of type and N-type thermoelectric arms are designed and arranged to form single-row multi-pair or multi-row array thermoelectric modules to increase the output voltage value.

Realize the filling of thermoelectric arms in the circular cavity of the flexible polyimide substrate. The physical and chemical properties of polyimide are stable. Compared with glass or silicon substrates, it can make the structure flexible and light, and increase the robustness. Its flexibility can Adapt to different surfaces.

The thermoelectric figure of merit of bismuth telluride material at room temperature is relatively high, and the use of bismuth telluride and its alloys can increase the power generation of thermoelectric power generation devices. However, due to poor mechanical properties of bismuth telluride (BiTe) material, it is easy to fracture. The bismuth telluride material directly processed on the flexible substrate is easy to break and cause the failure of the thermoelectric power generation unit. Therefore, the bismuth telluride material is wrapped in the polyimide circular cavity, and the flexibility of the substrate itself reduces the pressure and impact on the bismuth telluride material, thereby avoiding the failure of the thermoelectric power generation unit caused by the fracture of the thermoelectric material.

The above specific embodiments are used to explain the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification and change made to the present invention will fall into the protection scope of the present invention.

Claims (3)

1. a flexible thermo-electric generation micro unit structure, it is characterized in that: the honeycomb type circular cavity that has many rows and many even columns in substrate (1), except edge two row circular cavities, other circular cavity bottom has a micropore, interior the dripping of circular cavity that has micropore is coated with the described micropore of money base nano particle ink (2) filling, and covers bottom circular cavity; Equal alternate P type thermoelectric arm (3) and N-type thermoelectric arms (4) of being filled with in every row's circular cavity, the top of every pair of P type thermoelectric arm (3) and N-type thermoelectric arm (4) is connected with upper strata copper conductor respectively, upper copper wire is laid on upper strata flexible PCB (5) below, the P type thermoelectric arm (3) and the N-type thermoelectric arm (4) that often arrange micropore are one group, the circular cavity outer bottom that has micropore is connected with lower floor's copper conductor respectively, then, form successively flexible thermo-electric generation micro unit structure with identical connected mode.

2. the flexible thermo-electric generation micro unit of one according to claim 1 structure, is characterized in that: the material of described P type thermoelectric arm (3) and N-type thermoelectric arm (4) is the bismuth telluride of doping.

3. the flexible thermo-electric generation micro unit of one according to claim 1 structure, is characterized in that: the material of described substrate (1) and upper strata flexible PCB (5) is polyimides.