CN102868318B - Mini-type combined type energy collector based on PVDF (Poly Vinyli Dene Fluoride) and preparation method - Google Patents

Abstract

The invention provides a PVDF-based micro-composite energy harvester and a preparation method. The flexible polymer piezoelectric material PVDF is used to prepare a cantilever beam structure, and resonance occurs through the PVDF piezoelectric cantilever beam, and the vibration energy is converted into Electric energy; at the same time, the PDMS mass block containing magnetic nanoparticles fixed to it also vibrates with the vibration of the PVDF piezoelectric cantilever beam, so that the magnetic flux passing through the planar spiral coil electroplated on the substrate changes, and an induced electromotive force is generated. Thus output power on the external load. The composite energy harvester of the present invention uses the polymer piezoelectric material PVDF to replace the traditional piezoelectric material PZT, and collects energy through piezoelectric and electromagnetic methods, so that the output power and efficiency of the energy harvester can be significantly improved , and are biocompatible.

Description

PVDF-based miniature composite energy harvester and preparation method

technical field

The invention relates to a micro-energy collector based on a polymer piezoelectric material PVDF and a preparation method thereof, belonging to the field of micro-electromechanical systems.

Background technique

With the rapid development of micro-nano technology, a large number of new micro-nano devices and systems have been continuously developed, such as micro-generators, nano-structured optoelectronic devices, nano-drug delivery and targeted therapy for disease prevention and treatment, etc. However, micro-nano The power supply problem of nano products is becoming the main obstacle to its application, because the power supply of these micro and nano systems mainly relies on batteries. In order to avoid frequent battery replacement, this requires the battery's working life to be continuously extended, and in some special micro-nano products or devices, especially in implanted systems (such as cardiac pacemakers, implanted sensors, etc.) , replacing or charging the battery is even more difficult. The technical way to replace batteries as the energy source of micro-nano sensors is mainly to collect energy from the environment of micro-devices, and then convert the energy of the environment into electrical energy. Since vibrations exist in industries, buildings, and even living organisms (such as limb movement, blood flow, heart beating, etc.), piezoelectric energy harvesters for micro-electromechanical systems (MEMS) that collect environmental vibrations have attracted the attention of domestic and foreign counterparts. In the research that has been carried out, piezoelectric materials mostly use piezoelectric ceramic PZT, such as D Isarakorn et al. in "Therealization and performance of vibration energy harvesting MEMS devices based on anepitaxial piezoelectric thin film" (SMART MATERIALS AND STRUCTURES, 2011, VOL. 025015) (Chinese title: "Realization and Performance of a MEMS Vibration Energy Harvesting Device Based on Epitaxial Piezoelectric Film", International Journal: Precision Materials and Structures) reported the energy of a 1mm×2.5mm×0.015mm cantilever beam For the collector, the cantilever beam is epitaxially 0.5μm thick PZT and has a 1mm×0.5mm×0.23mm silicon mass. At a vibration frequency of 2.3kHz and a load of 5.6kΩ, it can generate 13μW and 0.27V energy. Jeon et al. in "MEMS power generator with transverse mode thin film PZT" (Sensors and Actuators A,2005,122:16-22) (Chinese title: "MEMS energy harvester based on PZT thin film d33 piezoelectric mode", international journal: Sensors and Actuators A) Another energy harvester based on a cantilever beam structure is reported in the article. The cantilever beam is composed of SiO ₂ or SiNx film, ZrO ₂ layer, PZT layer and interdigitated electrodes (Pt/Ti) and mass blocks, among which the ZrO ₂ layer can prevent the escape of charges in the piezoelectric layer. At a vibration frequency of 13.91kHz, the power reaches a maximum value of 1.01μW when the load is 5.2MΩ. However, due to the high density and high brittleness of piezoelectric ceramics, high-temperature annealing is required in the processing process, resulting in major deficiencies in device biocompatibility and efficiency, and the processing is difficult.

PVDF is a flexible biocompatible piezoelectric polymer material with strong piezoelectricity and can generate a large voltage when an external force is applied. However, due to the extremely large internal resistance of the piezoelectric material, the output current is very small. When a single piezoelectric energy harvesting is used, the output power is still low.

Contents of the invention

In order to solve the above problems, the present invention provides a micro piezoelectric and electromagnetic composite energy harvester based on the polymer piezoelectric material PVDF and a preparation method. The flexible polymer piezoelectric material PVDF (polyvinylidene fluoride) is used to replace the commonly used piezoelectric ceramic PZT, and it works together with the electromagnetic energy harvesting method, combined with MEMS bulk silicon and surface micromachining technology to prepare micro energy harvesters.

The miniature energy harvester of the present invention comprises three main parts: a substrate, a PVDF piezoelectric film, a PDMS quality block containing magnetic nanoparticles, and a planar spiral coil. The planar spiral copper coil is electroplated on the silicon wafer, and the PVDF piezoelectric film is located above or around the coil to form a cantilever beam structure, which is fixed at one end. The free end of the PVDF piezoelectric cantilever beam has a magnetic mass block.

When the natural frequency of the PVDF piezoelectric cantilever is close to or equal to the vibration frequency of the external environment, resonance occurs on the PVDF piezoelectric cantilever, and the PVDF piezoelectric cantilever converts vibration energy into electrical energy due to the piezoelectric effect, and the magnetic PDMS mass above it The block vibrates with the vibration of the PVDF piezoelectric cantilever beam, so that the magnetic flux passing through the planar helical coil changes. According to Faraday's law of electromagnetic induction, the planar helical coil will have an induced electromotive force, thereby outputting power on the external load.

A preparation method of a miniature energy harvester, comprising the steps of:

(a) processing and cleaning silicon wafers;

(b) Plasma-enhanced chemical vapor deposition (PECVD) of 1 μm SiO ₂ on the front side of the silicon wafer;

(c) 100 nm Ti/Cu seed layer sputtered;

(d) Throwing the positive resist, the first photolithography;

(e) Electroplating planar helical Cu coils;

(f) Glue rejection, second photolithography;

(g) Fabrication of PDMS support frames or vibration windows;

(h) Remove the photoresist and remove the seed layer

(i) Cut the PVDF piezoelectric film into a cantilever beam structure, and paste the PDMS mass block containing magnetic nanoparticles on the PVDF piezoelectric cantilever beam, and connect the PVDF piezoelectric cantilever beam with mass block with the planar spiral coil, PDMS support frame or vibration window combination.

The beneficial effect of the energy harvester based on piezoelectric polymer PVDF manufactured by the present invention is:

(1) The present invention includes two ways of energy collection: piezoelectric output of PVDF and electromagnetic output of magnetic mass block and coil, which can increase the output power and improve the efficiency of energy collection;

(2) The present invention uses the flexible polymer piezoelectric material PVDF as the piezoelectric cantilever beam, which can obtain greater energy output, and has good biocompatibility, and is suitable for biological applications. It not only provides self-power supply for micro-nano sensors It also provides the possibility for the wireless application of micro-nano sensors in living organisms, which can be applied to built-in biosensors, biomedical monitoring and biological living detection, etc.;

(3) The present invention uses a PDMS mass block containing magnetic nanoparticles to form a magnetic field. Compared with micro-assembly or manual adhesion of permanent magnets, the preparation process of the energy harvester is simpler, and the magnetic field can be changed by controlling the content of magnetic nanoparticles in PDMS strength;

(4) The PVDF polymer piezoelectric film of the present invention can also be applied in the manufacture of other MEMS devices and systems, such as piezoelectric brakes, piezoelectric sensors, and the like.

Description of drawings

Fig. 1 is the structural representation of the miniature composite energy harvester that contains flexible support;

Fig. 2 is the schematic diagram of vibrating cantilever beam of the present invention;

Fig. 3 is the process flow chart of embodiment one;

Fig. 4 is a structural schematic diagram of the free end of the PVDF piezoelectric cantilever beam and the output end of the planar helical coil in series;

Fig. 5 is a structural schematic diagram of the free end of the PVDF piezoelectric cantilever beam and the parallel output end of the planar helical coil;

Figure 6(a) is a schematic diagram of the front structure of a miniature composite energy harvester with a vibration window;

Figure 6(b) is a schematic diagram of the back structure of a miniature composite energy harvester with a vibration window;

Fig. 7 is the process flow chart of embodiment two.

in:

1-PVDF piezoelectric cantilever beam; 2-planar spiral coil; 3-PDMS mass block;

4—flexible support; 5—vibration window.

Detailed ways

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

A piezoelectric and electromagnetic composite MEMS energy harvester, including a substrate, a PVDF piezoelectric film, a planar spiral coil 2, a PDMS mass block 3 containing magnetic nanoparticles, and a flexible support 4 or a vibration window 5, including a flexible support 4 The miniature composite energy harvester is shown in Figure 1.

The PVDF piezoelectric film is made into a cantilever beam structure, its free end is connected with the PDMS mass block 3 containing magnetic nanoparticles, and the other end is fixed with a flexible support or a vibration window. Vibration energy is converted into electrical energy through the PVDF piezoelectric cantilever beam 1, and the electromagnetic induction output power between the PDMS mass block 3 containing magnetic nanoparticles and the planar helical coil 2 realizes the output of piezoelectric and electromagnetic composite energy.

The dimensions of the PVDF piezoelectric cantilever beam 1 are designed as follows:

According to the principle of elastic mechanics, the elastic coefficient of a single-end fixed beam is:

$\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; EWH</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, E is the Young's modulus of the cantilever beam, and L, W, and H are the length, width and thickness of the cantilever beam, respectively, as shown in Figure 2.

The natural frequency of the energy harvester system is:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; res</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula, m is the sum of the mass of the vibrating beam and the magnetic mass.

According to the Roundy model, for a given load resistance _RL , the output power of the piezoelectric cantilever is

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}{\mathrm{<span\; class="notranslate">\; dt</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; *</span>}}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&zeta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 4</span>}{\mathrm{<span\; class="notranslate">\; \&zeta;k</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&zeta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In the formula, b ^* is the geometric constant of the piezoelectric beam, t _c is the thickness of the piezoelectric layer, Y _C is the elastic modulus of the piezoelectric material, ε is the dielectric constant of the piezoelectric material, ζ is the damping coefficient, ω is the vibration angular frequency, C _P is the equivalent capacitance of the piezoelectric part, A _in is the input amplitude, and d is the piezoelectric coefficient.

According to (1)-(3), the resonant frequency and output power of the energy harvester can be determined, so as to design an energy harvester that collects different vibration frequencies of the external environment and has different output power. Some processing circuits can collect the energy of biological movement.

Example 1

A piezoelectric and electromagnetic composite MEMS energy harvester, including a substrate, a PVDF piezoelectric film, a planar spiral coil 2, a PDMS mass block 3 containing magnetic nanoparticles, and a flexible support 4, namely a PDMS support frame, as shown in Figure 1 shown. The PVDF piezoelectric film is made into a cantilever beam structure, and the substrate is composed of a silicon wafer with a layer of _SiO2 deposited on the surface. The planar spiral coil 2 is electroplated on the _SiO2 layer, and the flexible support 4 is also located on the _SiO2 layer. And located around the planar helical coil 2. The PVDF piezoelectric film is cut into a cantilever structure, and the PDMS mass block 3 containing magnetic nanoparticles is fixed on the free end of the PVDF piezoelectric cantilever 1, and the other end of the PVDF piezoelectric cantilever 1 is fixed on the flexible support 4, as shown in the figure 2 shown. The free end of the PVDF piezoelectric cantilever beam 1 is the output end, which can be connected in series with the output end of the planar spiral coil 2, as shown in Figure 4, or in parallel, as shown in Figure 5, depending on the specific situation.

When the vibration frequency in the environment is close to or equal to the natural frequency of the PVDF piezoelectric cantilever 1, it will cause the resonance of the PVDF piezoelectric cantilever 1, and the PVDF piezoelectric cantilever 1 converts vibration energy into electrical energy due to the piezoelectric effect. Realize the output of energy; at the same time, the PDMS mass block 3 containing magnetic nanoparticles at the free end of the PVDF piezoelectric cantilever 1 vibrates together with the PVDF piezoelectric cantilever 1, so that the magnetic flux passing through the planar spiral coil 2 changes, according to Faraday According to the law of magnetic induction, the planar helical coil 2 will generate an induced electromotive force, thereby outputting power on the external load.

A preparation method of a piezoelectric and electromagnetic composite MEMS energy harvester adopts the method of mechanically processing the surface, that is, forming a planar spiral coil by electroplating technology, and then forming a flexible support for fixing a cantilever beam by photolithography.

After routine cleaning and treatment of the silicon wafer (see Figure 3(a)), plasma-enhanced chemical vapor deposition (PECVD) of 1 μm SiO ₂ on the front side of the silicon wafer (see Figure 3(b)), and then:

(1) Sputtering Ti/Cu seed layer

A 200 nm Ti/Cu seed layer was prepared by vacuum sputtering. Sputtering for 1 hour under the condition of 50W power in a vacuum environment can obtain a Ti/Cu seed layer with a total thickness of 200nm, as shown in Figure 3(c).

(2) Electroplating to make planar spiral coil 2

After sputtering the Ti/Cu seed layer, a layer of 10 μm positive resist AZ P4903 was cast, the exposure time was 70s, and the development time was 120s, as shown in Figure 3(d), and then the planar spiral coil 2 was electroplated, as shown in Figure 3(e). The number of turns of the planar spiral coil 2 is 15, the wire width is 100 μm, the wire spacing is 100 μm, and the material is Cu.

(3) Making a flexible support (PDMS support frame)

After electroplating the planar spiral coil 2, throw off a layer of 10μm positive resist AZ P4903, the exposure time is 220s, and the development time is 150s, that is, Figure 3(f), and then PDMS is dripped at the exposed photoresist groove, as shown in the figure 3(g). Then vacuumize in a vacuum pot for 30 minutes to remove air bubbles in PDMS, and finally bake in an oven at 70°C for 2h. Take out the condensation, and after exposure and development without a plate, remove the photoresist and the seed layer to obtain the PDMS flexible support 4, as shown in Figure 3(h).

(4) Making magnetic mass blocks

Add magnetic nanoparticles into liquid PDMS, the mass ratio of PDMS and magnetic nanoparticles is 5:1, then vacuumize in a vacuum pot for 30 minutes to remove air bubbles in PDMS, and then magnetize the magnetic nanoparticles with a strong magnetic field , and finally baked in an oven at 70° C. for 2 hours. After taking out the condensation, manually cut into 2cm*2cm squares to obtain the PDMS mass 3 containing magnetic nanoparticles.

(5) Paste PVDF piezoelectric film, magnetic mass block, and flexible bracket to form an energy harvester

The present invention selects a 100 μm thick polyvinylidene fluoride (PVDF) piezoelectric film produced by Jinzhou Kexin Electronic Material Co., Ltd. Cut the PVDF piezoelectric film into a 2cm*5cm cantilever structure, connect the PDMS mass block containing magnetic nanoparticles to one end of the PVDF piezoelectric cantilever 1, and fix the other end of the PVDF piezoelectric cantilever 1 to the flexible support 4 on. At this time, the planar helical coil 2 is located under the PVDF piezoelectric cantilever beam 1 . The piezoelectric and electromagnetic composite MEMS energy harvester is completed, as shown in Figure 3(i).

Example 2

A preparation method of a piezoelectric and electromagnetic composite MEMS energy harvester, using a three-dimensional micromachining method combining bulk silicon and surface micromachining techniques, including a substrate, a PVDF piezoelectric film, a planar helical coil 2, and magnetic nanoparticles The PDMS mass block 3 also includes a vibration window 5, as shown in FIG. 6 . That is, the silicon is etched by bulk silicon micromachining technology to form the vibration window of the PVDF piezoelectric cantilever beam, and the planar spiral coil 2 is fabricated on the silicon chip by surface micromachining.

The manufacturing steps are roughly the same as those in Embodiment 1, except that after the planar spiral coil 2 is manufactured, the vibration window 5 is manufactured using wet etching technology instead of the flexible support 4 .

Step (3) is to make the vibration window, the process is shown in Figure 7, specifically:

The etchant used for wet etching SiO ₂ is buffered silicon oxide etchant, the composition of the etchant is HF:NH ₄ F:H ₂ O=84:339:510 (mass ratio), the etching temperature is 45°C, and the etching rate is 0.4μm/min. The corrosion of SiO ₂ is isotropic corrosion. Since the corrosion rate of HF acid to SiO ₂ is much higher than that of Si, under the masking effect of positive resist, SiO ₂ in the photolithographic pattern will be corroded by HF acid. After corroding SiO ₂ , use KOH solution (ratio KOH: H ₂ O = 44g: 100ml) to etch Si, the etching temperature is 85°C, and the etching rate is 1.4 μm/min. The corrosion of Si is anisotropic corrosion, which is HF The Si beneath the acid-etched _SiO2 is etched away, forming the vibration window 5 of the PVDF piezoelectric cantilever.

Step (4) The manufacturing process of the magnetic mass block is the same as the first embodiment.

The final step (5) the process of pasting PVDF piezoelectric film, magnetic mass block, and silicon wafer to form the energy harvester is as follows:

Cut the PVDF piezoelectric film into a cantilever structure of 2cm*5cm, connect the PDMS mass block 3 containing magnetic nanoparticles to one end of the PVDF piezoelectric cantilever 1, and fix the other end of the PVDF piezoelectric cantilever 1 on the silicon On the back of the sheet, the free end of the PVDF piezoelectric cantilever 1 (that is, the end connected to the PDMS mass block containing magnetic nanoparticles) is located in the reserved vibration window 5. At this time, the planar spiral coil 2 is located on the PVDF piezoelectric cantilever 1 side above. This completes the piezoelectric and electromagnetic composite MEMS energy harvester.

The above only lists typical embodiments of the present invention for the convenience of understanding by those skilled in the art, but the present invention is not limited thereto. Anyone with ordinary knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention shall be determined by the claims.

Claims (8)

1. A miniature compound type energy harvester, is characterized in that, comprises substrate, PVDF piezoelectric cantilever beam, planar helical coil and the PDMS mass block that comprises magnetic nanoparticle; Described PVDF piezoelectric cantilever beam is a film structure; The mass ratio of PDMS to magnetic nanoparticles in the PDMS mass is 5:1 or 10:1, and the PDMS mass is fixed at the free end of the PVDF piezoelectric cantilever; the planar spiral coil is located below the PVDF piezoelectric cantilever Or around, electroplated on the substrate. 2. The miniature composite energy harvester according to claim 1, wherein the free end of the PVDF piezoelectric cantilever is connected in series or in parallel with the output end of the planar helical coil. 3 . The miniature composite energy harvester according to claim 1 , further comprising a flexible support, located on the front surface of the substrate, and fixedly connected to the other end of the PVDF piezoelectric cantilever beam. 4 . 4. The miniature composite energy harvester as claimed in claim 1, further comprising a vibration window positioned on the substrate, the periphery of the PVDF piezoelectric cantilever, and the other end of the PVDF piezoelectric cantilever is fixed on Base back. 5. The miniature composite energy harvester according to claim 1, wherein the PDMS mass block is as wide as the piezoelectric cantilever beam. 6. A preparation method of a miniature composite energy harvester, comprising the steps of: (a) processing and cleaning the silicon wafer, and plasma-enhanced chemical vapor deposition of SiO ₂ on the front side of the silicon wafer; (b) Vacuum sputtering seed layer; (c) Throwing positive glue, photolithography for the first time, electroplating planar spiral coil; (d) Rejecting the positive glue, the second photolithography, and dripping the PDMS support frame; (e) exposing, developing, removing the photoresist, removing the seed layer; (f) Cut the PVDF piezoelectric film into a cantilever beam structure, and paste the PDMS mass block containing magnetic nanoparticles to one end of the PVDF piezoelectric cantilever beam; (g) Paste the other end of the PVDF piezoelectric cantilever on the PDMS support frame, and the planar helical coil is located under the PVDF piezoelectric cantilever. 7. A preparation method for a miniature composite energy harvester, comprising the steps of: (a) processing and cleaning the silicon wafer, and plasma-enhanced chemical vapor deposition of SiO ₂ on the front side of the silicon wafer; (b) Vacuum sputtering seed layer; (c) Throwing positive glue, photolithography for the first time, electroplating planar spiral coil; (d) The vibration window is made by wet etching technology; (e) exposing, developing, removing the photoresist, removing the seed layer; (f) Cut the PVDF piezoelectric film into a cantilever structure, and paste the PDMS mass block containing magnetic nanoparticles to one end of the PVDF piezoelectric cantilever as a free end; (g) The free end of the PVDF piezoelectric cantilever is located in the vibration window, the other end of the PVDF piezoelectric cantilever is fixed on the back of the silicon wafer, and the planar spiral coil is located around the PVDF piezoelectric cantilever. 8. the method as claimed in claim 6 or 7, is characterized in that, the described preparation step that comprises the PDMS quality block of magnetic nanoparticle is: (a) adding magnetic nanoparticles to liquid PDMS; (b) vacuumize to remove the air bubbles in the PDMS; (c) strengthening the magnetic field to magnetize the magnetic nanoparticles; (d) cut into pieces after baking and cooling.