CN100388553C

CN100388553C - Miniature biological fuel cell and its manufacturing method

Info

Publication number: CN100388553C
Application number: CNB2005100609538A
Authority: CN
Inventors: 吴坚; 周庆利; 于吉人; 叶璟
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2005-09-28
Filing date: 2005-09-28
Publication date: 2008-05-14
Anticipated expiration: 2025-09-28
Also published as: CN1776951A

Abstract

The present invention discloses a biological fuel cell which comprises a glass layer with a fuel inlet and a fuel outlet, a fuel cavity, a porous fuel electrode, a conducting macromolecular layer, a porous oxygen electrode, an oxygen cavity and a glass layer with an oxygen inlet and an oxygen outlet, wherein the porous fuel electrode and the porous oxygen electrode are respectively positioned at both sides of the conducting macromolecular layer; the fuel cavity is formed between the porous fuel electrode and the former glass layer; the oxygen cavity is formed between the porous oxygen electrode and the later glass layer; the porous oxygen electrode adopts a metal platinum electrode; the porous fuel electrode adopts a platinum electrode of which the surface is plated with ruthenium dioxide; the fuel in the fuel cavity is vitamin C. The present invention also discloses a preparation method of the cell; the electrode is electroplated with a ruthenium dioxide layer after being processed by a standard micro mechanical processing technology. The biological fuel cell can be used for industrial production and can be applied to micro biologic medicine detection and disease treatment.

Description

Miniature biofuel cell and method for manufacturing same

Technical Field

The invention relates to a micro-biological fuel cell based on micro-mechanical technology and a manufacturing method thereof, in particular to a micro-biological fuel cell adopting vitamin C as fuel and a manufacturing method thereof.

Background

A fuel cell is a device for converting chemical energy into electrical energy through an electrochemical reaction, and is different from a general chemical cell in that fuel and oxidant of the fuel cell are not stored inside the cell but outside the cell, and fuel needs to be continuously supplied to the inside of the cell during use. Currently, the fuel cell which is relatively successful mainly uses hydrogen, methanol and the like as fuel, and generally adopts metal platinum as an electrode material.

With the development of science and technology, various biomedical detection and treatment systems are also miniaturized more and more. However, during miniaturization, particularly for some implantable systems, there has been a problem with power supply. In response to this problem, the development of micro-biofuel cells has been considered using some common substances in living bodies and human bodies, such as glucose, as fuel.

Glucose is a common substance in the body, but oxidation of glucose requires catalysis by glucose oxidase. The activity of glucose oxidase is easily affected by temperature, pH value and the like. Vitamin C (ascorbic acid) is a relatively common substance in body fluids, but it is difficult to use vitamin C as a fuel for fuel cells because vitamin C is not easily oxidized on a general platinum electrode material.

Disclosure of Invention

The invention provides a micro-biofuel cell which adopts vitamin C as fuel and adopts a platinum electrode covered with ruthenium dioxide as a fuel electrode.

The invention also provides a preparation method of the cell, and the biofuel cell can be industrially produced and is applied to micro biomedical detection and disease treatment.

The micro biological fuel cell consists of a glass layer with a fuel inlet and a fuel outlet, a fuel cavity, a porous fuel electrode, a conductive polymer layer, a porous oxygen electrode, an oxygen cavity and a glass layer with an oxygen inlet and an oxygen outlet, wherein the porous fuel electrode and the porous oxygen electrode are respectively arranged at two sides of the conductive polymer layer, the fuel cavity is formed between the porous fuel electrode and the glass layer, the oxygen cavity is formed between the porous oxygen electrode and the glass layer, and the porous oxygen electrode adopts a metal platinum electrode; the porous fuel electrode adopts a platinum electrode with ruthenium dioxide plated on the surface, and the fuel in the fuel cavity is vitamin C.

The porous fuel electrode is a silicon wafer with a cavity, a plurality of microelectrode columns are arranged atthe bottom of the cavity, a platinum film layer is arranged on one side of each microelectrode column close to the conductive polymer layer, and a ruthenium dioxide layer is plated on the platinum film layer.

One side of the microelectrode column, which is close to the conductive polymer layer, is provided with a titanium/platinum film layer, and the platinum film layer is plated with a ruthenium dioxide layer.

According to research, ruthenium dioxide is a vitamin C oxidation catalyst, and on a ruthenium dioxide electrode, vitamin C is oxidized:

the electrons produced by the reaction reach the cathode through an external circuit, where oxygen is reduced to produce water:

the manufacturing method of the micro-biofuel cell comprises the following steps:

(1) the porous fuel electrode is firstly coated with photoresist on two sides of a silicon wafer, then the photoresist on the front side is exposed by adopting a template, the size of a fuel cavity is defined, and silicon etching is carried out in sodium hydroxide solution to form a silicon film with the thickness of about 100 microns. And exposing the photoresist on the reverse side by using a template to define the size of the micropore electrode, manufacturing the micropore electrode by using dry etching, removing the photoresist, and depositing a platinum film by using a sputtering method. Finally, a layer of ruthenium dioxide is deposited on the surface of the platinum electrode by an electroplating method.

When the sputtering method is used for depositing the platinum film, a layer of titanium film can be deposited firstly, and then a layer of platinum film is deposited.

The specific electroplating process of ruthenium dioxide is as follows:

the solution used for electroplating is 2-20 millimoles of ruthenium trichloride plus 0.01 mole of hydrochloric acid. In the electroplating process, a platinum electrode is used as a cathode, and a platinum sheet can be used as the other electrode (counter electrode). The initial pH of the plating solution is controlled to about 2. During the electroplating process, the current density through the cathode is controlled by a galvanostat to be in the range of 6 to 10 milliamps per square centimeter. The time for electroplating is around 30 to 60 minutes depending on the desired film thickness. And repeatedly washing the device with deionized water after the electroplating.

(2) Porous oxygen electrode

The porous oxygen electrode is fabricated in a process similar to that of the porous fuel electrode except that ruthenium dioxide plating is not required.

(3) Fuel chamber and oxygen chamber

The fuel chamber and the oxygen chamber are obtained by bonding a porous fuel electrode, a porous oxygen electrode and a glass layer with an inlet and an outlet, respectively.

(4) Conductive polymer layer

The conductive polymer layer can adopt some common conductive polymer materials, the conductive polymer layer and the porous fuel electrode, and the porous oxygen electrode is bonded together through a hot pressing method.

The invention adopts ruthenium dioxide as a catalyst for vitamin C oxidation, and ruthenium dioxide as an electrode, wherein the ruthenium dioxide catalyzes the oxidationof the vitamin C, thereby realizing the transmission of electrons and providing the supply of biological power.

Compared with the fuel cell which uses glucose oxidase to catalyze glucose, the micro-biological fuel cell of the invention uses ruthenium dioxide as an inorganic material, and has much better stability.

The micro-biological battery of the invention can be applied to micro-biomedical detection and disease treatment.

The manufacturing of the microbial battery can adopt a standard micro-machining process, the machining method is mature, and the microbial battery can be industrially produced in a large scale.

Drawings

FIG. 1 is a schematic view of the structural principle of a micro-biofuel cell of the present invention;

FIG. 2 is an enlarged view of part A of FIG. 1;

FIG. 3 is a flow chart of the process of manufacturing the porous fuel electrode of the micro biofuel cell of the present invention;

fig. 4 is a current-voltage characteristic diagram of the fuel cell of the present invention.

Detailed Description

The cell of the invention is composed of a glass layer 1 with an inlet and an outlet 2, a fuel cavity 3, a porous fuel electrode 4, a conductive polymer layer 12, a porous oxygen electrode 10 and an oxygen cavity 11, wherein the porous fuel electrode 4 and the porous oxygen electrode 10 are respectively arranged at two sides of the conductive polymer layer 12, the fuel cavity 3 is formed between the porous fuel electrode 4 and the glass outer layer 1, the oxygen cavity 10 is formed between the porous oxygen electrode 9 and the glass outer layer 1, the porous oxygen electrode 10 is a silicon wafer with a cavity, a plurality of microelectrode columns 9 are arranged at the bottom of the cavity, and one side of the microelectrode column 9 close to the conductive polymer layer 12 is provided with a titanium/platinum film layer 8.

The porous fuel electrode 4 is a silicon wafer with a cavity, a plurality of microelectrode columns 5 are arranged at the bottom of the cavity, a titanium/platinum film layer 6 is arranged on one side of each microelectrode column 5 close to the conductive polymer layer 12, a ruthenium dioxide layer 7 is plated on each titanium/platinum film layer 6, and the fuel used in the fuel cavity 3 is vitamin C.

The preparation method of the specific device comprises the following steps:

1. porous fuel electrode 4

The specific manufacturing process is shown in fig. 3. A 4 inch silicon wafer 5 (shown in fig. 3 a) with both sides polished is first coated with photoresist 13 (shown in fig. 3 b) on both sides and then the photoresist on the front side is exposed using a stencil to define the size of the fuel chamber 3 (shown in fig. 3 c), which in this example has a bottom area of 25 square millimeters. Silicon etching was performed in 8 molar sodium hydroxide solution (fig. 3 d) to form a silicon film with a cavity 3 of about 100 microns, and the opposite photoresist was exposed using a template to define the size of the microelectrode 5 (fig. 3 e), which in this example had a total of 225 micropores each 200 microns in diameter, and the microelectrode 5 was fabricated by dry etching (fig. 3 f). The photoresist was then removed and a titanium/platinum film layer 6 (shown in fig. 3 g) was deposited by sputtering, the titanium film being used primarily as the adhesion layer and having a thickness of 50nm and the platinum film having a thickness of 100 nm. The titanium film is mainly used for increasing the adhesion of platinum and has no influence on the overall characteristics of the fuel cell.

These processes may all use standard micromachining processes.

Finally, a layer of ruthenium dioxide 7 is deposited on the surface of the titanium/platinum film layer 6 by an electroplating method (shown in figure 3 h), and the specific electroplating process is as follows:

the solution used for electroplating is 5 millimole of ruthenium trichloride added with 0.01 mole of hydrochloric acid, and the initial pH value of the electroplating solution is controlled to be about 2. In the electroplating process, a platinum electrode is used as a cathode, a platinum sheet is used as a counter electrode, and the current density passing through the cathode is controlled by a constant current meter to be about 5 milliamperes per square centimeter in the electroplating process. The time of electroplating is about 30 minutes. And repeatedly washing the device with deionized water after the electroplating.

2. Porous oxygen electrode 10

The porous oxygen electrode 10 is fabricated in a process similar to that of the porous fuel electrode except that the ruthenium dioxide 4 plating is not required.

3. Fuel chamber 3 and oxygen chamber 11

The fuel cavity 3 and the oxygen cavity 11 are respectively obtained by an anode bonding method of the porous fuel electrode 4, the porous oxygen electrode 10 and the glass sheet 1.

4. The conductive polymer layer 12

The conductive polymer layer 12 may be made of a conductive polymer material such as Nafion (r) film manufactured by dupont. The conductive polymer layer 12, the porous fuel electrode 4, and the porous oxygen electrode 10 are bonded together by thermocompression.

During use, a 1 molar solution of vitamin C is passed through the fuel chamber 3 at a flow rate of 4 ml per minute. The oxygen in the oxygen chamber 11 is the oxygen in the air.

Fig. 3 shows the current-voltage characteristics of the fuel cell, showing that the output voltage of the cell is about 0.5 volts under low current load conditions (2.5 milliamps per square centimeter). When the load current increased to 12 milliamps per square centimeter, the output voltage of the battery also dropped to 0.11 volts. The current required in the microbial sensor is small, and the fuel cell of the invention can meet the requirements of the microbial sensor.

Claims

1. Miniature biofuel cell, including the glass layer that has fuel entry and export, the fuel chamber, porous fuel electrode, electrically conductive high molecular layer, porous oxygen electrode, oxygen chamber and have the glass layer of oxygen entry and export, its characterized in that: the porous fuel electrode and the porous oxygen electrode are respectively arranged on two sides of the conductive polymer layer, a fuel cavity is formed between the porous fuel electrode and the glass outer layer, an oxygen cavity is formed between the porous oxygen electrode and the glass layer, and the porous oxygen electrode is a metal platinum electrode; the porous fuel electrode adopts a platinum electrode with ruthenium dioxide plated on the surface, and the fuel in the fuel cavity is vitamin C.

2. The miniature biofuel cell of claim 1 wherein: the porous fuel electrode is a silicon wafer with a cavity, a plurality of microelectrode columns are arranged at the bottom of the cavity, a platinum film layer is arranged on one side of each microelectrode column close to the conductive polymer layer, and a ruthenium dioxide layer is plated on the platinum film layer.

3. The miniature biofuel cell of claim 2 wherein: one side of the microelectrode column, which is close to the conductive polymer layer, is provided with a titanium/platinum film layer.

4. The method for manufacturing a micro biofuel cell as set forth in claim 1, comprising a porous fuel electrode, which is prepared by the steps of: firstly, coating photoresist on two sides of a silicon wafer, then exposing the photoresist on the front side by adopting a template to define the size of a fuel cavity, and carrying out silicon etching in a sodium hydroxide solution to form a silicon film with a cavity; exposing the photoresist on the reverse side by using a template to define the size of the microelectrode column, and manufacturing the microelectrode column by using dry etching; removing the photoresist, depositing a platinum film on the microelectrode column by a sputtering method, and depositing a layer of ruthenium dioxide on the surface of the platinum electrode by an electroplating method.

5. The manufacturing method according to claim 4, characterized in that: the electroplating process of the ruthenium dioxide layer comprises the following steps: electroplating solution is 2-20 mol ruthenium trichloride hydrochloric acid solution, the initial pH value is 1-3, and electroplating is carried out by taking a platinum electrode as a cathode and a platinum sheet as an anode.

6. The manufacturing method according to claim 4, characterized in that: the electroplating process of the ruthenium dioxide layer comprises the following steps: the current density through the cathode during electroplating is between 6 and 10 milliamps per square centimeter.

7. The manufacturing method according to claim 4, 5 or 6, characterized in that: a titanium film is firstly deposited on the microelectrode column by a sputtering method, and then a platinum film is deposited.