A laser-induced field-induced droplet ionization device

Abstract

The present invention discloses a laser-induced field-induced droplet ionization device, belonging to the field of ion sources for mass spectrometry analysis. The device primarily comprises a laser beam proximity switch, a high-voltage electrode, a grounding electrode, a stainless steel capillary, a signal amplifier, an Arduino Nano development board, and a host computer. The laser beam proximity switch consists of a transmitter and a receiver. A droplet passing through the laser light path between two vertically mounted electrodes closes the proximity switch. A pulse signal is emitted the instant the switch closes. The Arduino Nano development board reads this signal and outputs a single pulse. This pulse is amplified to the kilovolt level and applied to the high-voltage electrode for field-induced droplet ionization of moving droplets. The device achieves the following technical benefits: the host computer transmits a pulse width and a command to start or stop reading the A0 pin value to the Arduino Nano development board. The Arduino Nano development board then returns a string indicating the A0 pin status to the host computer for display.

Description

Technical Field

[0001] The invention relates to a laser-induced field-induced droplet ionization device, belonging to the field of ion sources for mass spectrometry analysis. Background Art

[0002] Field-induced droplet ionization (FDI) devices use a high-voltage single-pulse signal to elongate a droplet in an electric field, forming a Taylor cone and ejecting sub-droplets. Because the sub-droplets are ejected from the surface, the device is often used to study chemical reactions at gas-liquid interfaces. Current FDI devices use a manual click trigger, which is suitable for stationary droplets suspended at the end of a capillary. However, for moving droplets, it is difficult to determine when the droplet moves near the mass spectrometer inlet. Therefore, sub-droplets ejected from both ends of the droplet after manual click triggering may not be received and detected by the mass spectrometer. In order to allow the FDI signal of a moving droplet to be detected by the mass spectrometer, a laser proximity switch can be used to detect the moment a droplet passes by and automatically emit a pulse signal to trigger FDI. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a laser-induced field-induced droplet ionization device that triggers field-induced droplet ionization by activating a laser-induced proximity switch. To this end, our solution is as follows:

[0004] A laser-induced field-induced droplet ionization device primarily comprises a laser proximity switch, a high-voltage plate, a ground plate, a stainless steel capillary, a signal amplifier, an Arduino Nano development board, and a host computer. A droplet is suspended at the end of the capillary and then propelled downward by an injection pump. As the droplet passes through the laser light path, the laser radiation emitted by the proximity switch's transmitter is partially blocked. This weakened laser radiation is sensed by the receiver, causing the proximity switch to close and emit a pulse signal. The Arduino Nano development board reads this pulse signal and emits a single pulse. The pulse width is set by the host computer. This pulse signal is then applied to the high-voltage plate via the signal amplifier, triggering field-induced droplet ionization.

[0005] The laser beam proximity switch described in this device consists of a transmitter and a receiver. The brown wire from the transmitter connects to the brown wire from the receiver and the positive terminal of the power supply, while the blue wire from the transmitter connects to the blue wire from the receiver and the negative terminal of the power supply. The beam proximity switch used is an NPN type, and the Arduino Nano development board is connected between the positive terminal of the power supply and the black wire from the receiver.

[0006] The high-voltage electrode and the grounding electrode described in the device are installed vertically and fixed on the ceramic tube. The stainless steel capillary is installed on the three-dimensional moving platform, and the end of the capillary is adjusted to above the two electrodes.

[0007] The signal amplifier described in this device uses a 6N135 high-speed optocoupler as its core. A low-voltage single pulse is connected to the 6N135 to control the on and off of the high-voltage relay, thereby outputting a high-voltage single pulse of the corresponding pulse width.

[0008] The Arduino Nano development board described in this device reads the pulse signal sent by the radio switch from the A0 pin and sends a low-voltage single pulse signal from the D11 pin.

[0009] The host computer of this device communicates with the Arduino Nano development board through the serial port, mainly controlling the Arduino Nano development board to start and stop reading the A0 pin value.

[0010] Compared with other field-induced droplet ionization devices, this device has the following characteristics:

[0011] This device uses a laser-beamed proximity switch to trigger field-induced droplet ionization of moving droplets. The host computer transmits a pulse width and a command to start or stop reading the A0 pin value to the Arduino Nano development board. The Arduino Nano development board then returns a string representing the A0 pin status to the host computer for display. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The figure is a schematic diagram of the installation of a laser-induced field droplet ionization device.

[0013] Figure 2 The diagram is a proximity switch connection diagram for a laser-induced field-induced droplet ionization device.

[0014] Figure 3 The present invention is a single pulse signal amplification circuit diagram of a laser-induced field-induced droplet ionization device.

[0015] Figure 4 This is a diagram of the host computer interface of a laser-induced field-induced droplet ionization device. DETAILED DESCRIPTION

[0016] A laser-induced field-induced droplet ionization device is described in further detail below with reference to the accompanying drawings.

[0017] Figure 1Shown is the following components of a laser-induced field-induced droplet ionization device: a laser beam proximity switch transmitter 1, a laser beam proximity switch receiver 2, a ground plate 3, a high-voltage plate 4, a ceramic tube 5, a stainless steel capillary 6, a droplet 7, and a laser beam 8. The ground plate 3 and the high-voltage plate 4 are mounted vertically opposite each other and fixed to four horizontal ceramic tubes 5. The laser beam proximity switch transmitter 1 and receiver 2 are mounted horizontally on either side of the plates, and the laser beam 8 emitted by the transmitter can be received by the receiver. The optical path of the laser beam should be between the two plates. When the stainless steel capillary 6 is adjusted so that the droplet 7 at its end falls through the optical path of the laser beam, the proximity switch receiver senses the weakening of the laser beam, switches on and off, and emits a pulse signal.

[0018] Figure 2 The figure below shows how to connect a proximity switch. The brown wires at both the transmitter and receiver of the proximity switch are connected to the positive pole of the power supply, and the blue wires at both the transmitter and receiver are connected to the negative pole of the power supply. The A0 pin of the Arduino Nano development board is connected to the positive pole of the power supply, and the GND pin is connected to the black wire at the receiver. After the Arduino Nano development board reads the pulse signal from the proximity switch from the A0 pin, it will send a single pulse from the D11 pin. Figure 3 As shown, the single pulse is connected to the circuit from the IN port, and the high-voltage single pulse is output from the OUT port by controlling the on and off of the relay. The high-voltage single pulse is applied to the high-voltage plate to cause field-induced droplet ionization.

[0019] Serial communication is used between the host computer and the Arduino Nano development board. Figure 4The following shows the host computer control program interface. Select the correct communication port (e.g., "COM6") and click the "Connect" button to establish a serial communication connection between the Arduino and the host computer. The baud rate is set to 115200. If the Arduino Nano development board and the host computer are not connected via USB when the program interface opens, click the "Refresh" button after connecting the cables so that the correct communication port appears in the drop-down list box. Set the pulse width (e.g., 15ms) and click the "Start" button to send the string "a\nd15" to the Arduino. If the Arduino receives this string, it will send the string "s1;15;0" back to the computer and display it in the text box. It will also begin to continuously read the value of pin A0. If the A0 pin value indicates that the proximity switch is indeed emitting a pulse signal and not background noise, the string "d1;15;2.10" (2.10 is the voltage corresponding to the pin value) is sent to the computer and displayed in the text box. Pin D11 is set high. After a 15ms delay, it is set low again, effectively sending a single pulse with a width of 15ms. Click the "Stop" button to send the string "o\nd15" to the Arduino. If the Arduino receives this string, it sends the string "s0;15;0" back to the computer and displays it in the text box, stopping reading the A0 pin value. Click the "Disconnect" button to disconnect the communication between the computer and the Arduino.

[0020] In this device, the host computer transmits the pulse width and the command to start reading the value of pin A0 to the Arduino Nano development board, which then enters the actual working state to read the pulse signal from the beam proximity switch. A droplet passes through the laser optical path, causing the proximity switch to close and emit a pulse signal. After reading the signal, the Arduino Nano outputs a single pulse of the set width. This pulse, after passing through the signal amplification circuit, is used to trigger field-induced droplet ionization.

[0021] The above content is an example of a laser-induced field-induced droplet ionization device. Any deletions or substitutions made by those skilled in the art within the scope of the above description shall fall within the scope of protection of the present invention.

Claims

1. A laser-induced field-induced droplet ionization device, comprising: Laser proximity switch, high-voltage plate, ground plate, stainless steel capillary, ceramic tube, droplet, laser beam, signal amplifier, Arduino Nano development board and a host computer; The high voltage plate and the grounding plate are installed vertically and fixed on four horizontal ceramic tubes; The laser beam proximity switch is composed of a transmitter and a receiver. The transmitter and the receiver are horizontally mounted on both sides of a high-voltage plate and a ground plate. The laser beam emitted by the transmitter can be received by the receiver. The optical path of the laser beam is between the high-voltage plate and the ground plate. The end of the stainless steel capillary is adjusted to be above the laser light path so that the falling droplet can pass through the light path; The droplet is suspended at the end of the capillary and then falls with the help of the injection pump. When the droplet falls through the laser light path, the laser radiation emitted by the transmitting end of the laser proximity switch is partially blocked. The receiving end senses the laser weakening, causing the laser proximity switch to close and emit a pulse signal. After reading the pulse signal, the Arduino Nano development board emits a single pulse signal, the width of which is set by the host computer. The single pulse signal is then applied to the high-voltage plate via a signal amplifier, thereby triggering field-induced droplet ionization. The specific process of triggering field-induced droplet ionization is as follows: The host computer transmits the pulse width and the command to start reading the A0 pin value to the Arduino Nano development board, so that the Arduino Nano enters the actual working state to read the pulse signal from the laser proximity switch; The A0 pin of the Arduino Nano development board is connected to the positive pole of the power supply, and the D11 pin is connected to the IN port of the signal amplifier; the Arduino Nano development board reads the pulse signal of the laser proximity switch from the A0 pin and outputs a low-voltage single pulse from the D11 pin; this single pulse is connected to the circuit from the IN port and outputs a high-voltage single pulse from the OUT port by controlling the on and off of the relay; this high-voltage single pulse is applied to the high-voltage plate to cause field-induced droplet ionization.

2. The laser-induced field-induced droplet ionization device according to claim 1, characterized in that: The brown wire of the laser proximity switch's transmitting end is connected to the brown wire of the receiving end and the positive pole of the power supply, and the blue wire of the transmitting end is connected to the blue wire of the receiving end and the negative pole of the power supply.

3. The laser-induced field-induced droplet ionization device according to claim 1, characterized in that: Connect the Arduino Nano development board between the positive pole of the power supply and the black wire of the laser proximity switch receiving end.

4. The laser-induced field-induced droplet ionization device according to claim 1, characterized in that: The signal amplifier uses 6N135 high-speed optocoupler as the core. The low-voltage single pulse is connected to 6N135 to control the on and off of the high-voltage relay, and then outputs a high-voltage single pulse of corresponding pulse width.

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