US-12625108-B2 - Sensor element for gas sensor having nanorod structure and manufacturing method thereof, and gas sensor

US12625108B2US 12625108 B2US12625108 B2US 12625108B2US-12625108-B2

Abstract

A sensor element for a gas sensor has a substrate, and a channel formed in the substrate and configured to allow gases to flow therein, wherein the channel has nanoscale nanorods inside, the nanorods interfering with a flow of gaseous phase materials in the gases flowing in the channel, and the gas sensor has the sensor element for the gas sensor, and a detection sensor to detect the gaseous phase materials exiting the sensor element for the gas sensor.

Inventors

Jung Hwan Seo

Assignees

HONGIK UNIVERSITY INDUSTRY-ACADEMIA COOPERATION FOUNDATION

Dates

Publication Date: 20260512
Application Date: 20240207
Priority Date: 20230208

Claims (18)

1 . A sensor element for a gas sensor, comprising: a substrate; and a channel formed in the substrate and configured to allow gases to flow to a detection sensor that is configured to detect gaseous phase materials in the gas sensor, wherein the channel has nanoscale nanorods inside, the nanorods interfering with a flow of the gaseous phase materials in the gases flowing in the channel, wherein the channel is formed based on a groove formed in the substrate by etching, wherein the nanorods are formed based on an unetched portion of the substrate other than the groove, and wherein lengths of the nanorods vary and the nanorods protrude irregularly from a bottom of the channel.
2 . The sensor element for the gas sensor according to claim 1 , wherein a porous material capable of adsorbing the gaseous phase materials is coated on the inside of the channel, and wherein the channel is a separation path to separate the gaseous phase materials in the gases flowing in the channel into types during movement by repeated adsorption and desorption to/from a structure in the channel.
3 . The sensor element for the gas sensor according to claim 1 , wherein the channel is filled with an adsorbent material capable of capturing the gaseous phase materials, and wherein the channel is a concentration chamber for capturing the gaseous phase materials in the gases flowing in the channel inside the channel.
4 . The sensor element for the gas sensor according to claim 1 , wherein a porous material capable of adsorbing the gaseous phase materials is coated on an inside of a first portion of the channel formed in the substrate, and wherein an adsorbent material capable of capturing the gaseous phase materials is filled in a second portion of the channel formed in the substrate.
5 . A method for manufacturing the sensor element for the gas sensor according to claim 1 , the method comprising: preparing the substrate; forming a masking layer on the substrate; removing the masking layer corresponding to an area in which the channel will be formed; and etching the groove in the substrate to form the channel, wherein the masking layer is etched together during the etching and a material of the masking layer breaks down into nanoparticles, and the nanoparticles accumulate within the groove and act as a micro-mask, and wherein a portion of the substrate that is not etched by the micro-mask forms the nanorods in the channel.
6 . The method for manufacturing the sensor element for the gas sensor according to claim 5 , wherein the forming of the masking layer comprises: forming a hard masking layer on the substrate, and applying a photosensitizer onto the hard masking layer, and wherein the removing of the masking layer comprises: removing the photosensitizer corresponding to an area in which the channel will be formed, and removing the hard masking layer exposed by removing the photosensitizer.
7 . The method for manufacturing the sensor element for the gas sensor according to claim 5 , wherein a distance between two adjacent channel walls that form the channel is set such that all the nanoparticles do not outgas during the etching and some of the nanoparticles remain in the groove.
8 . The method for manufacturing the sensor element for the gas sensor according to claim 7 , wherein a thickness of the channel walls that form the channel is set to a thickness such that the channel walls do not collapse during the etching.
9 . The method for manufacturing the sensor element for the gas sensor according to claim 7 , further comprising: coating a porous material capable of adsorbing the gaseous phase materials on an inside of the channel.
10 . A method for manufacturing a sensor element for a gas sensor, the method comprising: preparing a substrate; forming a masking layer on the substrate; removing the masking layer corresponding to an area in which a channel will be formed; and etching a groove in the substrate to form the channel, wherein the masking layer is etched together during the etching and a material of the masking layer breaks down into nanoparticles, and the nanoparticles accumulate within the groove and act as a micro-mask, and wherein a portion of the substrate that is not etched by the micro-mask forms nanorods in the channel, wherein an auxiliary wall is formed between channel walls that form the channel, and wherein the removing of the masking layer comprises not removing the masking layer corresponding to an area in which the auxiliary wall will be formed within the area in which the channel will be formed.
11 . The method for manufacturing the sensor element for the gas sensor according to claim 10 , wherein a first distance between a channel wall of the channel walls and the auxiliary wall and a second distance between adjacent auxiliary walls are set such that all the nanoparticles do not outgas during the etching and some of the nanoparticles remain in the groove.
12 . The method for manufacturing the sensor element for the gas sensor according to claim 11 , wherein a thickness of the auxiliary wall is set to a thickness such that the auxiliary wall collapses during the etching.
13 . The method for manufacturing the sensor element for the gas sensor according to claim 10 , further comprising: coating an adsorbent material capable of capturing gaseous phase materials on an inside of the channel.
14 . The method for manufacturing the sensor element for the gas sensor according to claim 6 , wherein the hard masking layer is formed by depositing aluminum on the substrate.
15 . A gas sensor, comprising: the sensor element for the gas sensor according to claim 1 ; and the detection sensor configured to detect the gaseous phase materials exiting the sensor element for the gas sensor.
16 . The gas sensor according to claim 15 , wherein a porous material capable of adsorbing the gaseous phase materials is coated on the inside of the channel, and the channel is a separation path along which the gaseous phase materials in the gases move at different speeds depending on components, and wherein the detection sensor is configured to detect the gaseous phase materials leaving the separation path at a time interval.
17 . The gas sensor according to claim 15 , wherein an adsorbent material capable of capturing the gaseous phase materials is coated on the inside of the channel, and the channel is a concentration chamber capable of capturing the gaseous phase materials in the gases, and wherein the gas sensor further comprises a heating device to selectively heat the concentration chamber.
18 . The gas sensor according to claim 15 , wherein a porous material capable of adsorbing the gaseous phase materials is coated on an inside of a first portion of the channel other than a second portion of the channel acting as a concentration chamber, and is a separation path along which the gaseous phase materials in the gases move at different speeds depending on components, and wherein the gaseous phase materials exiting the concentration chamber enter the separation path and are separated into types based on the gaseous phase materials being heated by a heating device, and wherein the detection sensor is configured to detect the gaseous phase materials leaving the separation path at a time interval.

Description

DESCRIPTION OF GOVERNMENT-FUNDED RESEARCH AND DEVELOPMENT This research is conducted by Hongik University, and funded by Convergence Research Group project of National Research Foundation of Korea, Ministry of Science and ICT, Republic of Korea (Development of micro-GC sensor system for detecting mixed gas in air pollution, No. 1711141350). CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Korean Patent Application No. 10-2023-0016961, filed on Feb. 8, 2023, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference. BACKGROUND 1. Field The present disclosure relates to a sensor element for a gas sensor and a manufacturing method thereof, and a gas sensor, and more particularly, to a sensor element for an ultra-small gas sensor with improved separation performance of gaseous phase materials in a gas mixture using a nanorod structure and a manufacturing method thereof, and a gas sensor. 2. Description of the Related Art Studies have been made on gas sensors to quickly and accurately detect gaseous phase materials that may cause damage such as hazards or contamination in industrial environments. FIG. 1 is a schematic diagram of a conventional gas sensor. According to the conventional art, the gas sensor includes a concentration chamber 1 to filter hazardous materials in air to produce concentrates and store the concentrates, a separation path 2 into which the hazardous material concentrates in the concentration chamber 1 are injected, and a detection sensor 3 to detect the concentration of each of the types of the hazardous materials leaving the separation path 2. The concentration chamber 1, the separation path 2 and the detection sensor 3 are in fluid communication with each other by a channel 4. More specifically, gases including gaseous phase materials (hereinafter, in some cases, referred to as “gas mixture” or simply “gases” in the present disclosure) are fed into the concentration chamber 1. The gaseous phase materials included in the gases are adsorbed onto an adsorbent packed in the concentration chamber 1. When heat is applied for a predetermined time after preconcentration of the gaseous phase materials, the gaseous phase material concentrates stored in the concentration chamber 1 are separated from the adsorbent by thermal energy, and carrier gas 30 flowing across the concentration chamber 1 carries the concentrates out of the chamber 1. The carrier gas 30 carrying the gaseous phase materials flows to the separation path 2. FIG. 2 shows schematically the inner part of the separation path 2 of the conventional gas sensor. As shown in FIG. 2, a porous material 20 is coated on the inner surface of the separation path 2 where the gaseous phase materials 11, 12 may be attached. The gaseous phase materials 11, 12, most of which are organic compounds are attached to the porous polymer by van der Waals forces. In this instance, when the carrier gas 30 flows in the separation path 2, the gaseous phase materials 11, 12 attached to the porous material 20 are separated from the porous material 20 by the force of the carrier gas 30, move a predetermined distance and attach to the porous material 20 again as they lose mobility, and this process repeats. Since the gaseous phase materials 11, 12 differ in mass and van der Waals forces interacting with the porous material 20 depending on components, as shown in FIG. 2, the gaseous phase materials 11, 12 of different types differ in frequency and distance to which the gaseous phase materials 11, 12 attach the porous material 20 and then separate and move. That is, the gaseous phase materials 11, 12 move in the separation path 2 at different movement speeds depending on components. For example, among a first material 11 indicated in triangle and a second material 22 indicated in circle, the second material 22 moves faster. The gaseous phase materials 11, 12 leaving the exit of the separation path 2 in a sequential order are detected by the detection sensor 3. According to the conventional art, to ensure separation accuracy of the gaseous phase materials, the separation path 2 having a very narrow gap and thereby a very small cross sectional area extends, for example, over about 3 m. To this end, the separation path 2 extends in a serpentine pattern in a column shape. The conventional art achieved the gas sensor with accuracy and small size through this configuration. However, there is still a demand for sensors with smaller size and improved sensing capability in the gas sensor field. SUMMARY The present disclosure discloses a gas sensor having a smaller size while maintaining sensing accuracy and/or for significantly improving sensing accuracy at the same size and a sensor element for a gas sensor. According to an aspect of the present disclosure, there is provided a sensor element for a gas sensor including a substrate, and a channel formed in the substrate and