# US 2021/0280767 A1 · Flexible piezoelectric sensor based on 4d printing and preparation method thereof

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- Number: US 2021/0280767 A1
- Document ID: US20210280767A1
- Status: Published application
- Kind: A1
- Application number: 17/037,745
- Filed: 2020-09-30
- Published: 2021-09-09
- Earliest claimed: 2020-03-09
- Assignees: Huazhong University of Science and Technology
- Applicants: Huazhong University of Science and Technology
- Inventors: Bin Su; Hongzhi Wu; Chunze Yan; Yusheng Shi
- Web page: https://patentgrep.com/patent/US20210280767A1

## CPC

- B29C 64/386: Data acquisition or data processing for additive manufacturing
- B22F 10/18: by mixing binder with metal in filament form, e.g. fused filament fabrication [FFF]
- B22F 10/28: Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
- B22F 10/38: to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures
- B22F 12/30: Platforms or substrates
- B29C 64/153: using layers of powder being selectively joined, e.g. by selective laser sintering or melting
- B29C 64/307: Handling of material to be used in additive manufacturing
- B33Y 80/00: Products made by additive manufacturing
- H10N 30/302: {Sensors}
- H10N 35/80: Constructional details
- B22F 10/12: by photopolymerisation, e.g. stereolithography [SLA] or digital light processing [DLP]
- B33Y 10/00: Processes of additive manufacturing
- Y02P 10/25: Process efficiency
- Y10T 29/42: Piezoelectric device making
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The disclosure belongs to the technical field of additive manufacturing, and discloses a flexible piezoelectric sensor based on 4D printing and a preparation method thereof. The sensor includes a magnetic part and a conductive part, wherein: the conductive part includes two substrates disposed opposite to each other and a spiral structure disposed between the two substrates. Both the two substrates and the spiral structure are made of conductive metal materials. The magnetic part has a flexible porous structure and is arranged between the two substrates to generate a magnetic field. When the substrate is subjected to external pressure, the spiral structure and the magnetic part are compressed simultaneously, the magnetic flux passing through the spiral structure changes, and the voltage of the two substrates changes, by measuring the voltage change of the two substrates to reflect the change of external pressure, the pressure measuring process is achieved.

## Claims

### Claim 1

A flexible piezoelectric sensor based on 4D printing, wherein the sensor comprises a magnetic part and a conductive part, wherein:
the conductive part comprises two substrates disposed opposite to each other and a spiral structure disposed between the two substrates, both the two substrates and the spiral structure are formed of conductive metal materials;
the magnetic part is a flexible porous structure and arranged between the two substrates to generate a magnetic field;
when the substrate is subjected to external pressure, the spiral structure and the magnetic part are compressed simultaneously, a magnetic flux passing through the spiral structure changes, and a voltage of the two substrates changes, by measuring a voltage change of the two substrates to reflect the change of external pressure, a pressure measuring process is achieved.

### Claim 2 (depends on 1)

The flexible piezoelectric sensor based on 4D printing according to claim 1, wherein a raw material of the magnetic part is composite powder formed by mixing polymer powder and magnetic powder, wherein the polymer powder is thermoplastic polyurethane (TPU) or polydimethylsiloxane (TPMS), and the magnetic powder is neodymium iron boron (NdFeB) magnetic powder, iron chromium cobalt-based permanent magnet alloy powder or permanent ferrite powder.

### Claim 3 (depends on 2)

The flexible piezoelectric sensor based on 4D printing according to claim 2, wherein a mass fraction of the magnetic powder is 10% to 40%, which not only ensures flexibility of the magnetic part, but also ensures magnetism of the magnetic part.

### Claim 4 (depends on 1)

The flexible piezoelectric sensor based on 4D printing according to claim 1, wherein a ratio of a compression modulus of the spiral structure to a compression modulus of the magnetic part is 0.1 to 10.

### Claim 5 (depends on 1)

The flexible piezoelectric sensor based on 4D printing according to claim 1, wherein a slot is provided on the substrate for fixing the magnetic part.

### Claim 6 (depends on 1)

The flexible piezoelectric sensor based on 4D printing according to claim 1, wherein the piezoelectric sensor is a unit, and multiple units are connected in series or in parallel to obtain a multi-unit piezoelectric sensor, the multi-unit piezoelectric sensor is configured to amplify a signal of a single piezoelectric sensor.

### Claim 7 (depends on 1)

A preparation method of the flexible piezoelectric sensor according to claim 1, the method comprising the following steps:
S1 selecting the polymer powder and the magnetic powder as raw materials, mixing the polymer powder and the magnetic powder to prepare the composite powder, calculating and obtaining a compression modulus of the spiral structure in the conductive part, constructing a porous structure of the magnetic part, and calculating and obtaining a compression modulus of the porous structure, forming the porous structure by a 3D printing method, thereby obtaining the required magnetic part; magnetizing the magnetic part so that the magnetic part obtains permanent magnetism;
S2 constructing a three-dimensional structure of the conductive part, and simultaneously constructing the compression modulus of the spiral structure according to the compression modulus of the porous structure, such that a ratio of the compression modulus of the spiral structure of the conductive part to the compression modulus of the porous structure is 0.1 to 10, selecting a raw material of the conductive part, performing 3D printing by using the raw material according to the 3D model, thereby obtaining the required conductive part;
S3 assembling the magnetic part with permanent magnetism between the substrates of the conductive part to obtain the required piezoelectric sensor.

### Claim 8 (depends on 7)

The preparation method according to claim 7, wherein in step S1, the 3D printing forming method is a metal 3D-printing process such as selective laser melting (SLM), electron beam melting (EBM), or Laser engineered net shaping (LENS).

### Claim 9 (depends on 7)

The preparation method according to claim 7, wherein in step S3, the 3D printing forming method is a polymer 3D-printing process such as selective laser sintering (SLS), fused deposition modelling (FDM), or photo-curing based on ultra violet.