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

Abstract

The invention provides a mini-type combined type energy collector based on PVDF (Poly Vinyli Dene Fluoride) and a preparation method. A cantilever structure is prepared by using a flexible polymer piezoelectric material PVDF, resonance is generated through the PVDF piezoelectric cantilever, and vibration is converted into electric energy by using a piezoelectric effect; and meanwhile, a PDMS (Poly Di Methyl Siloxane) mass block containing nanometer particles, which is fixedly connected with the mini-type combined type energy collector, vibrates with the vibration of the PVDF piezoelectric cantilever, so that the magnetic flux of passing through a plane spiral coil electrically plated on a substrate can be varied, and sensing electromotive force is generated. Therefore, output power is externally loaded. The mini-type combined type energy collector provided by the invention uses a polymer piezoelectric material PVDF to replace a traditional piezoelectric material PZT (Piezoelectric Transducer), and energy collection can be carried out through a piezoelectric manner and an electromagnetic manner, so that the output power and the efficiency of the energy collector can be obviously improved, and the mini-type combined type energy collector is biologically compatible.

Description

Based on miniature combined type energy collecting device and the preparation method of PVDF

Technical field

The present invention relates to a kind of Minitype energy collector based on polymer piezo material PVDF and preparation method, belong to micro electro mechanical system field.

Background technology

Along with the fast development of micro & nano technology, a large amount of novel micro nanometer device and system constantly develop, as microgenerator, nanostructure opto-electronic device, Nano medication for preventing and curing diseases transports and targeted therapy etc., but, the powerup issue of micro-nano product is just becoming the major obstacle of its application of puzzlement, and reason is that the power supply of these micro-nano systems at present mainly relies on battery.For avoiding changing battery frequently, this just requires that the working life of battery constantly extends, and in some special micro-nano products or device, particularly in embedded system (as cardiac pacemaker, implantable sensor etc.), changes battery or charging difficulty especially.The power conversion of environment, as the technological approaches mainly collecting energy from the environment of microdevice of the micro-nano transducer energy, is then become electric energy by substituting battery.Due to vibration industry, build even in organism (as limb motion, blood flow, the heartbeat etc.) moment exist, so MEMS (micro electro mechanical system) (MEMS) the piezoelectric type energy collector gathering ambient vibration obtains the attention of colleague both at home and abroad.In the research carried out, piezoelectric many employings piezoelectric ceramic PZT, if the people such as D Isarakorn are at " Therealization and performance of vibration energy harvesting MEMS devices based on anepitaxial piezoelectric thin film " (SMART MATERIALS AND STRUCTURES, 2011, VOL.025015) (Chinese exercise question: " a kind of realization of the MEMS vibration energy collector part based on extension piezoelectric membrane and performance ", International Periodicals: precise materials and structure) report the energy collecting device comprising 1mm × 2.5mm × 0.015mm cantilever beam in article, the PZT that cantilever beam extension 0.5 μm is thick with the siliceous gauge block of 1mm × 0.5mm × 0.23mm, in the vibration frequency of 2.3kHz, under the load of 5.6k Ω, 13 μ W can be produced, the energy of 0.27V.The people such as Jeon are at " MEMS power generator withtransverse mode thin film PZT " (Sensors and Actuators A, 2005,122:16-22) report the another kind of energy collecting device based on cantilever beam structure in (Chinese exercise question: " the MEMS energy collecting device based on pzt thin film d33 piezoelectricity pattern ", International Periodicals: transducer and actuator A) article.Cantilever beam is by SiO ₂or SiNx film, ZrO ₂layer, PZT layer and cross one another electrode (Pt/Ti) and mass are formed, wherein, and ZrO ₂layer can stop the escape of electric charge in piezoelectric layer.Under the vibration frequency of 13.91kHz, power reaches maximum 1.01 μ W when load is 5.2M Ω.But due to piezoelectric ceramic density large, fragility is large, needs high annealing, cause the aspects such as device bio-compatibility, efficiency to have larger deficiency, and difficulty of processing is larger in the course of processing.

PVDF is a kind of polymeric piezoelectric material of bio-compatible of flexibility, has very strong piezoelectricity, when applying external force, can produce larger voltage.But because the internal resistance of piezoelectric is large especially, the electric current of output is very little, and when adopting single piezoelectric type energy collection, power output is still on the low side.

Summary of the invention

For solving the problem, the invention provides a kind of miniature piezoelectric based on polymer piezo material PVDF and Electromagnetic heating formula energy collecting device and preparation method.Utilize flexible polymer piezoelectric PVDF(Kynoar) replace at present conventional piezoelectric ceramic PZT, and with the acting in conjunction of electromagnetic energy acquisition method, prepare Minitype energy collector in conjunction with MEMS body silicon and surface micromachined technology.

Minitype energy collector of the present invention, comprises substrate, PVDF piezoelectric membrane, the PDMS mass comprising magnetic nanoparticle and planar spiral winding three major parts.Silicon chip is electroplated snail copper coil, PVDF piezoelectric membrane is positioned at top or the surrounding of coil, makes cantilever beam structure, and makes it single-ended clamped, with magnetic property gauge block on the free end of PVDF piezoelectric cantilever.

When PVDF piezoelectric cantilever natural frequency close to or when equaling the vibration frequency of external environment, there is resonance in PVDF piezoelectric cantilever, vibrational energy is converted into electric energy due to piezoelectric effect by PVDF piezoelectric cantilever, magnetic PDMS mass above it also vibrates together along with the vibration of beam of PVDF piezoelectric cantilever, thus change through the magnetic flux of planar spiral winding, according to Faraday's electromagnetic induction law, planar spiral winding will have induced electromotive force, thus in applied load power output.

A preparation method for Minitype energy collector, comprises the steps:

(a) process, cleaning silicon chip;

B () is at the SiO of front side of silicon wafer plasma reinforced chemical vapour deposition (PECVD) 1 μm ₂;

The Ti/Cu Seed Layer of (c) sputtering 100nm;

(d) positive-glue removing, first time photoetching;

(e) plating snail Cu coil;

(f) whirl coating, second time photoetching;

G () makes PDMS bracing frame or vibration window;

H () is removed photoresist, is removed Seed Layer

(i) PVDF piezoelectric membrane is cut into cantilever beam structure, and the PDMS mass including magnetic nanoparticle is pasted on PVDF piezoelectric cantilever, by with mass PVDF piezoelectric cantilever and planar spiral winding, PDMS bracing frame or vibrate window combination.

The beneficial effect of the energy collecting device based on piezopolymer PVDF utilizing the present invention to manufacture is:

(1) the present invention contains the mode of two kinds of energy acquisitions: the piezoelectric type of PVDF exports and magnetic property gauge block, coil electromagnetic type export, can power output be increased, the efficiency of raising energy acquisition;

(2) the present invention adopts flexible polymer piezoelectric PVDF as piezoelectric cantilever, larger Energy transmission can be obtained, and there is good bio-compatibility, be applicable to organism application, not only provide technological approaches for micro-nano transducer self-power supply, and provide possibility for the wireless application in vivo of micro-nano transducer, built-in biometric sensor, biological medicine monitoring and biological living detection etc. can be applied to;

(3) the present invention utilizes the PDMS mass comprising magnetic nanoparticle to form magnetic field, compare micro assemby or manual adhesion permanent magnet, make the preparation technology of energy collecting device more simple, and magnetic field intensity can be changed by the content of magnetic nanoparticle in control PDMS;

(4) PVDF polymer piezo film of the present invention, can also make in other MEMS and system and apply, such as piezoelectric type brake, piezoelectric transducer etc.

Accompanying drawing explanation

Fig. 1 is the structural representation of the miniature combined type energy collecting device containing flexible support;

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

Fig. 3 is the process chart of embodiment one;

Fig. 4 is that the free end of PVDF piezoelectric cantilever is connected with planar spiral winding the structural representation of output;

Fig. 5 is the free end of PVDF piezoelectric cantilever and the structural representation of planar spiral winding parallel outputs;

Fig. 6 (a) is the miniature combined type energy collecting device Facad structure schematic diagram containing vibration window;

Fig. 6 (b) is the miniature combined type energy collecting device structure schematic diagram containing vibration window;

Fig. 7 is the process chart of embodiment two.

Wherein:

1-PVDF piezoelectric cantilever; 2-planar spiral winding; 3-PDMS mass;

4-flexible support; 5-vibration window.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment, technical scheme of the present invention is further described.

A kind of piezoelectricity and Electromagnetic heating formula MEMS energy collecting device, comprise substrate, PVDF piezoelectric membrane, planar spiral winding 2, comprise the PDMS mass 3 of magnetic nanoparticle, and flexible support 4 or vibration window 5, containing flexible support 4 miniature combined type energy collecting device as shown in Figure 1.

Described PVDF piezoelectric membrane makes cantilever beam structure, and its free end is connected with the PDMS mass 3 comprising magnetic nanoparticle, the other end and flexible support or vibrate window and fix.By PVDF piezoelectric cantilever 1, vibrational energy is converted into electric energy, and comprises the electromagnetic induction power output between the PDMS mass 3 of magnetic nanoparticle and planar spiral winding 2, realize the output of piezoelectricity and Electromagnetic heating formula energy.

The size design of PVDF piezoelectric cantilever 1 is as follows:

According to principle of elasticity, the coefficient of elasticity of single clamped beam is:

$k=\frac{{\mathrm{EWH}}^3}{{4L}^3}---\left(1\right)$

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

The natural frequency of energy collecting device system is:

$f_{\mathrm{res}}=2\mathrm{\π}\sqrt{\frac{k}{m}}---\left(2\right)$

In formula, m is the quality sum of walking beam and magnetic property gauge block.

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

$P=\frac{1}{{\mathrm{\ω}}^2}\frac{R_L{C}_P^2{\left(\frac{Y_C{\mathrm{dt}}_c{b}^{*}}{\mathrm{\ϵ}}\right)}^2{A}_{\mathrm{in}}^2}{({4\mathrm{\ζ}}^2+k^2){\left(R_L{C}_P\mathrm{\ω}\right)}^2+4{\mathrm{\ζk}}^2\left(R_L{C}_P\mathrm{\ω}\right)+{4\mathrm{\ζ}}^2}---\left(3\right)$

In formula, b ^*for piezoelectric beam geometric constant, t _cfor piezoelectric layer thickness, Y _cfor piezoelectric modulus of elasticity, ε is piezoelectric dielectric constant, and ζ is damping coefficient, and ω is angle of throw frequency, C _pfor piezoelectric equivalent capacity, A _infor input amplitude, d is piezoelectric modulus.

According to (1)-(3) formula, resonance frequency and the power output of energy collecting device can be determined, thus design the energy collecting device gathering the different vibration frequency of external environment, there is different output power, if acquisition target is organism, as long as more additional treatment circuits, just can gather organism kinergety.

Embodiment 1

A kind of piezoelectricity and Electromagnetic heating formula MEMS energy collecting device, comprise substrate, PVDF piezoelectric membrane, planar spiral winding 2, comprise the PDMS mass 3 of magnetic nanoparticle, also comprise flexible support 4, i.e. PDMS bracing frame, as shown in Figure 1.PVDF piezoelectric membrane makes cantilever beam structure, and described substrate is one deck SiO by surface deposition ₂silicon chip form, planar spiral winding 2 is plated on SiO ₂on layer, flexible support 4 is also positioned at SiO ₂on layer, and be positioned at planar spiral winding 2 around.PVDF piezoelectric membrane is cut into cantilever beam structure, and the PDMS mass 3 comprising magnetic nanoparticle is fixed on the free end of PVDF piezoelectric cantilever 1, and the other end of PVDF piezoelectric cantilever 1 is clamped on flexible support 4, as shown in Figure 2.The free end of PVDF piezoelectric cantilever 1 is output, can connect with planar spiral winding 2 output, as shown in Figure 4, also can be in parallel, as shown in Figure 5, concrete condition can depend on the needs.

When the vibration frequency in environment and PVDF piezoelectric cantilever 1 natural frequency close to or when equaling, will cause the resonance of PVDF piezoelectric cantilever 1, vibrational energy is converted into electric energy due to piezoelectric effect by PVDF piezoelectric cantilever 1, realizes the output of energy; Simultaneously, the PDMS mass 3 comprising magnetic nanoparticle of PVDF piezoelectric cantilever 1 free end vibrates together along with PVDF piezoelectric cantilever 1, magnetic flux through planar spiral winding 2 is changed, according to Faraday's electromagnetic induction law, planar spiral winding 2 can produce induced electromotive force, thus in applied load power output.

A kind of piezoelectricity and Electromagnetic heating formula MEMS energy collecting device preparation method, employing surface is the method for machining, namely utilizes electroplating technology to form planar spiral winding, and then photoetching forms cantilever mounted beam flexible support used.

After silicon chip being carried out to routine cleaning, process (see Fig. 3 (a)), at the SiO of front side of silicon wafer plasma reinforced chemical vapour deposition (PECVD) 1 μm ₂(see Fig. 3 (b)), then:

(1) sputtered with Ti/Cu Seed Layer

The method of vacuum sputtering is adopted to prepare the Ti/Cu Seed Layer of 200nm.In vacuum environment 50W power condition under sputtering 1 hour, the Ti/Cu Seed Layer that gross thickness is 200nm can be obtained, as shown in Figure 3 (c).

(2) plating makes planar spiral winding 2

After sputtered with Ti/Cu Seed Layer, get rid of positive glue AZ P4903, the time for exposure 70s of one deck 10 μm, developing time 120s, i.e. Fig. 3 (d), then electroplate planar spiral winding 2, i.e. Fig. 3 (e).The number of turn of planar spiral winding 2 is 15, and conductor width is 100 μm, and wire pitch is 100 μm, and material is Cu.

(3) flexible support (PDMS bracing frame) is made

After plating planar spiral winding 2, then get rid of positive glue AZ P4903, the time for exposure 220s of one deck 10 μm, developing time 150s, i.e. Fig. 3 (f), the photoresist groove place's instillation PDMS be then exposed, as shown in Fig. 3 (g).Then in vacuum kettle, vacuumize 30 minutes to remove the bubble in PDMS, the baking oven finally putting into 70 DEG C toasts 2h.Take out condensation, after version exposure, development, remove photoresist, Seed Layer, PDMS flexible support 4 can be obtained, as shown in Fig. 3 (h).

(4) magnetic property gauge block is made

Magnetic nanoparticle is added in the PDMS of liquid state, the mass ratio of PDMS and magnetic nanoparticle is 5:1, then in vacuum kettle, vacuumize 30 minutes to remove the bubble in PDMS, then magnetize magnetic nanoparticle with a high-intensity magnetic field, the baking oven finally putting into 70 DEG C toasts 2h.Be cut manually to the square of 2cm*2cm after taking out condensation, the PDMS mass 3 comprising magnetic nanoparticle can be obtained.

(5) PVDF piezoelectric membrane, magnetic property gauge block, flexible support formation energy collecting device is pasted

What the present invention selected is 100 μm of thick Kynoar (PVDF) piezoelectric films that Jinzhou Ke Xin Electron Material Co., Ltd produces.PVDF piezoelectric membrane is cut out the cantilever beam structure of 2cm*5cm, the PDMS mass comprising magnetic nanoparticle is connected with one end of PVDF piezoelectric cantilever 1, and the other end of PVDF piezoelectric cantilever 1 is fixed on flexible support 4.Now, planar spiral winding 2 is positioned at the below of PVDF piezoelectric cantilever 1.Piezoelectricity and Electromagnetic heating formula MEMS energy collecting device complete at this point, as Fig. 3 (i) shown in.

Embodiment 2

A kind of piezoelectricity and Electromagnetic heating formula MEMS energy collecting device preparation method, adopt the three-dimensional micro-machining that body silicon and surface micromachined technology combine, comprise substrate, PVDF piezoelectric membrane, planar spiral winding 2, comprise the PDMS mass 3 of magnetic nanoparticle, also involving vibrations window 5, as shown in Figure 6.Namely utilize the method etch silicon of bulk silicon micro mechanic process technology, form PVDF piezoelectric cantilever vibration of beam window, and make planar spiral winding 2 by the method for surface micromachined on silicon chip.

Its making step is roughly the same with embodiment 1, only after the planar spiral winding 2 that completes, then adopts wet etching technique to make vibration window 5, and no longer makes flexible support 4.

Step (3) is the making of vibration window, and process as shown in Figure 7, is specially:

Wet etching SiO ₂corrosive agent used is buffer oxide silicon etch solution, and corrosive liquid composition is HF:NH ₄f:H ₂o=84:339:510(mass ratio), etching temperature is 45 DEG C, and corrosion rate is 0.4 μm/min.SiO ₂corrosion be isotropic etch, due to HF acid to SiO ₂corrosion rate much larger than the corrosion to Si, therefore under the masking action of positive glue, the SiO in litho pattern place ₂will by HF acid corrosion.Corrosion SiO ₂after, adopt KOH solution (proportioning KOH:H ₂o=44g:100ml) corrode Si, etching temperature is 85 DEG C, and corrosion rate is 1.4 μm/and the corrosion of min, Si is anisotropic etch, by the SiO of HF acid etch ₂the Si of below is etched away, and forms PVDF piezoelectric cantilever vibration of beam window 5.

The manufacturing process of step (4) magnetic property gauge block is identical with embodiment one.

The process that final step (5) stickup PVDF piezoelectric membrane, magnetic property gauge block, silicon chip form energy collecting device is:

PVDF piezoelectric membrane is cut out the cantilever beam structure of 2cm*5cm, the PDMS mass 3 comprising magnetic nanoparticle is connected with one end of PVDF piezoelectric cantilever 1, and the other end of PVDF piezoelectric cantilever 1 is fixed on silicon chip back side, the free end (one end be namely connected with the PDMS mass comprising magnetic nanoparticle) of PVDF piezoelectric cantilever 1 is positioned at reserved vibration window 5, now, planar spiral winding 2 is positioned at above the side of PVDF piezoelectric cantilever 1.Piezoelectricity and Electromagnetic heating formula MEMS energy collecting device complete at this point.

Below only enumerate exemplary embodiments of the present invention, for convenience of the understanding of personnel in this area, but the present invention is not as limit.Have in any art and usually know the knowledgeable, without departing from the spirit and scope of the present invention, when doing a little change and retouching, therefore protection scope of the present invention is as the criterion with claims.

Claims (8)

1. a miniature combined type energy collecting device, is characterized in that, comprises substrate, PVDF piezoelectric cantilever, planar spiral winding and comprises the PDMS mass of magnetic nanoparticle; Described PVDF piezoelectric cantilever is membrane structure; In described PDMS mass, the mass ratio of PDMS and magnetic nanoparticle is 5:1 or 10:1, and described PDMS mass is fixed on the free end of PVDF piezoelectric cantilever; Described planar spiral winding is positioned at below or the surrounding of PVDF piezoelectric cantilever, is plated in substrate.

2. miniature combined type energy collecting device as claimed in claim 1, is characterized in that, the free end of described PVDF piezoelectric cantilever and the output serial or parallel connection of planar spiral winding.

3. miniature combined type energy collecting device as claimed in claim 1, is characterized in that, also comprise flexible support, be positioned on substrate front surface, affixed with the other end of PVDF piezoelectric cantilever.

4. miniature combined type energy collecting device as claimed in claim 1, is characterized in that, also comprises a vibration window, is positioned on substrate, the periphery of PVDF piezoelectric cantilever, and the other end of PVDF piezoelectric cantilever is fixed in backside of substrate.

5. miniature combined type energy collecting device as claimed in claim 1, is characterized in that, described PDMS mass and piezoelectric cantilever are with wide.

6. a preparation method for miniature combined type energy collecting device, comprises the steps:

A () process, cleaning silicon chip, at front side of silicon wafer plasma reinforced chemical vapour deposition SiO ₂;

(b) vacuum sputtering Seed Layer;

(c) positive-glue removing, first time photoetching, plating planar spiral winding;

(d) positive-glue removing, second time photoetching, instillation PDMS bracing frame;

E () exposure, development, remove photoresist, remove Seed Layer;

F PVDF piezoelectric membrane is cut into cantilever beam structure by (), and the PDMS mass including magnetic nanoparticle is pasted one end of PVDF piezoelectric cantilever;

G the other end of PVDF piezoelectric cantilever pastes on PDMS bracing frame by (), planar spiral winding is positioned at below PVDF piezoelectric cantilever.

7. a preparation method for miniature combined type energy collecting device, comprises the steps:

A () process, cleaning silicon chip, at front side of silicon wafer plasma reinforced chemical vapour deposition SiO ₂;

(b) vacuum sputtering Seed Layer;

(c) positive-glue removing, first time photoetching, plating planar spiral winding;

D () adopts wet etching technique to make vibration window;

E () exposure, development, remove photoresist, remove Seed Layer;

F PVDF piezoelectric membrane is cut into cantilever beam structure by (), and the PDMS mass including magnetic nanoparticle is pasted one end of PVDF piezoelectric cantilever, as free end;

G the free end of PVDF piezoelectric cantilever is positioned at vibration window by (), the other end of PVDF piezoelectric cantilever is fixed on silicon chip back side, and planar spiral winding is positioned at around PVDF piezoelectric cantilever.

8. method as claimed in claims 6 or 7, is characterized in that, described in include the PDMS mass of magnetic nanoparticle making step be:

A () adds magnetic nanoparticle in liquid PDMS;

B () vacuumizes, remove the bubble in PDMS;

C () adds high-intensity magnetic field and magnetizes magnetic nanoparticle;

Block is cut into after (d) baking, condensation.