CN1686048A - Skin moisture measuring method - Google Patents
Skin moisture measuring method Download PDFInfo
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- CN1686048A CN1686048A CN 200510011875 CN200510011875A CN1686048A CN 1686048 A CN1686048 A CN 1686048A CN 200510011875 CN200510011875 CN 200510011875 CN 200510011875 A CN200510011875 A CN 200510011875A CN 1686048 A CN1686048 A CN 1686048A
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Abstract
A method for measuring the water content of skin includes making a probe contact with skin to be measured, transmitting square wave signals at 50 KHz or lower, measuring impedance value, amplifying, A/D conversion, storing the value in single-chip computer, and comparing it with the voltage-water content values in a table to obtain the water content.
Description
Technical field
The invention belongs to the bio-electrical impedance measuring technical field, particularly a kind of impedance bioelectrical measurement method that is used to measure the human body skin moisture.
Background technology
The skin of human body is mainly by three organizational compositions: subcutaneous tissue, dermal tissue and epithelial tissue.The outermost of epithelial tissue is the cutin skin that is gathered into folds by 20 multilamellar deckzelle compact reactors.Though the cutin skin probably has only 20um thick, this layer albuminous membranae covered all surface of human body, and the activity of earning a bare living in the environment is externally had important function.The cutin skin is effective barrier of defense against bacterial and chemical substance, and simultaneously, it allows the moisture evaporation of human body remain on a very low level, has only 0.2 to 0.5mg/h/cm
2, this makes the people can live in very exsiccant environment.When it was in health status, it is many that contained moisture is Duoed when unhealthy.When only comprising more than 10% moisture, the cutin skin is only flexible, otherwise its can hardening and fragility.Exsiccant skin brings disease to the people easily.Therefore, the moisture of measurement human body skin (mainly being the cutin skin) can be used as the important method of the health status of evaluating skin.
Modal skin moisture measuring method is a water content of measuring keratodermatitis and a part of epidermis (thick 100 μ m altogether) by the electric class parameter (capacitance, AC conductivity etc.) of measuring skin indirectly, and wherein relatively more commonly used is the capacitance of measuring skin.Because the dielectric constant of water is considerably beyond other constituents of skin such as keratin and oils and fats, so the cutaneous equivalent capacitance value of how many meetings of moisture, moisture content of skin is many more, and the dielectric constant of skin is big more.The moisture of human body skin is difficult to directly measure by gauge, in actual measurement, and can be by obtaining the result indirectly with big or small relevant, the measured easily auxiliary parameter of moisture.General human body skin moisture measurement instrument is an equivalent capacity of measuring the skin that contacts with electrode, promptly sets up the corresponding relation of moisture and its equivalent capacitance value of skin, reflects the size of moisture by the size of electric capacity.But because the numerical value of equivalent capacity is generally very little, gauge structurally with on the circuit all has strict requirement.For example, the contact pressure of electrode and skin can have influence on the size of equivalent capacity, so need guarantee the constant machinery of contact pressure for measuring probe designs one.The probe shape of measuring is also very big affects measurement effect, and as interdigital or concentric-ring pattern, different form differences is very big, and the cost that need drop on probe is also more.And, the frequency of the pumping signal that capacitive measuring method is used is very high, generally arrive several MHz at 100KHz, and different corresponding the differences of the skin response degree of depth of driving frequency, being that high-frequency measurement can not guarantee that the object of measuring has only the cutin skin, is to be unfavorable for the accuracy measured and relate to epithelial tissue even dermal tissue.
The equivalent resistance of measuring skin is the another kind of common method of moisture measurement.Generally need a sine wave as driving source, owing to have influence on the problem of certainty of measurement, sine wave can not have too big distortion, and wants well stability, and this has higher requirement to device.Same reason, the phase discriminator that resistance measurement method needs also has higher requirement.This just makes the cost of this method than higher, is not suitable for using the field portable.
Summary of the invention
The objective of the invention is to solve the complex structure, measuring frequency height of moisture of skin measuring device in the prior art, the problem that cost is high.The inventor is by analyzing the organizational structure of human body skin, in conjunction with electrical performance testing to different skin matter human body skins, if find with " electrode---skin---electrode " structural equivalents to be a resistance network, compared with simple equivalence is simple electric capacity or resistance, more can reflect the water content of human body skin exactly.
Therefore, the present invention proposes a kind of skin moisture measuring method, it is characterized in that: use two no surface insulation layer covered metal electrodes as measuring probe, with described measuring probe contact measured skin surface, make skin surface to be measured directly be connected electrically in the RC charging and discharging circuit, measuring object is and the outer field equivalent eccentric electrical impedance value of the contacted skin keratin of described measuring probe; To the pumping signal that described measuring probe provides is square-wave signal below the frequency 50KHz; Only use a circuit amplifier element to form amplifying circuit the response signal that described measuring probe receives is carried out processing and amplifying; Gather magnitude of voltage after the above-mentioned amplification by the AD conversion method, be stored in the single-chip microcomputer, according to being stored in the magnitude of voltage in the single-chip microcomputer and the relation table of moisture content value, find out corresponding moisture content value again.
The structure of the measuring device that the present invention adopts mainly is made up of 4 parts and two electrodes, is respectively square-wave generator, electric capacity, resistance, amplifier element and probe electrode.The probe of measuring is two no surface insulation layer covered metal electrodes S and M, and electrode S is as the source electrode of output drive signal, and it directly links to each other with square-wave generator, exports square-wave signal below the frequency 50KHz as pumping signal by square-wave generator; Electrode M is a measurement electrode, receives the response signal of returning from skin reflex, and it is connected successively with described electric capacity, described resistance and ground.Extract the negative terminal input of the amplifier element of receiving response signal from the line of electric capacity, resistance, amplify the back output voltage values, be stored in the single-chip microcomputer as measurement result through amplifier element.
Operation principle of the present invention mainly is to utilize the charge/discharge character in RC loop to realize.By the basic charge that resistance, electric capacity are formed, its characteristic parameter is the time constant of charge/discharge, and time constant has characterized the fundamental characteristics of circuit, i.e. the speed degree of the change in voltage on the electric capacity in the circuit.The circuit that time constant is big, the change in voltage of electric capacity is slow relatively in the circuit, and the transformation period that just needs is longer; Otherwise it is then opposite.Time constant can be calculated by resistance, the electric capacity of built-up circuit, calculates formula to be: τ=R * C.When the value of the resistance of circuit or electric capacity changed, the charge/discharge constant of circuit also can change.By the change amount of observation, Measuring Time constant τ, can learn the change degree of the component parameters of built-up circuit, this change amount has reflected resistance, changes in capacitance simultaneously.When the attribute of measured target is the association of resistance and electric capacity, utilize the characteristic of charge time constant, can reach the purpose of the electrical impedance attribute of measurement target.The inventor is by analyzing the organizational structure of human body skin, in conjunction with electrical performance testing to different skin matter human body skins, the structure of discovery human body skin can be equivalent to resistance, electric capacity string and connect the electrical impedance network of composition on electrical characteristics, the anti-characteristic of the overall resistance that this network shows is along with very big difference can appear in the difference of skin moisture content.Utilize the variation characteristics of the time constant of charge the impedance operator of this electrical impedance network can be measured.
In the present invention, the RC loop of square-wave generator, electrode S, skin, electrode M, electric capacity, resistance and ground composition charge/discharge in sequential series.Generate square wave as the pumping signal of measuring by square-wave generator, because the generation ratio of square wave is easier to realize, the square-wave signal that generates still can simply and effectively controlled on the frequency on the waveform, and this just makes the present invention not need complicated sine-wave generator as driving source when using.The frequency limitation of square wave and can be regulated change easily below 50KHz, can guarantee that so measured skin scope is limited to the cutin skin.Because principle of the present invention is that the skin equivalence is the electrical impedance network, will its electrical impedance directly be connected electrically in the charge/discharge loop when measuring, so the measuring probe of selecting for use is two no surface insulation layer covered metal electrodes.The placement form of electrode can change because of needs, can parallelly place, and also can place or the interdigital placement by concentric-ring pattern; No matter be which kind of form, need only during measurement and guarantee that probe electrode fully contacts with skin, and do not need the complicated apparatus structure that keeps in touch constant pressure.Through the excitation of square-wave signal, promptly be the response signal of measuring at the voltage waveform of the line place of electric capacity and resistance node, as long as this signal is the result that just can obtain measuring through the processing of an amplifier element.
The voltage result who is obtained by measuring circuit and the moisture of skin exist corresponding relation.By the depositor the inside that the method for instrumental calibration can be deposited instrument with the form of data drawing list with this corresponding relation, when reality is used, find out the moisture content value of the magnitude of voltage correspondence that measures by the method for tabling look-up.The method of demarcating is to use the filter paper of suction as the simulation human body skin, and the moisture of filter paper can be measured the voltage result by the method for the invention on the one hand, can obtain filter paper water content absolute value by the method that oven dry is weighed on the other hand.These two results make comparisons, and just can obtain the magnitude of voltage that the method for the invention obtains and the corresponding relation of moisture.Demarcate the back and carry out the evaluation that actual human body skin is measured by other sophisticated moisture of skin measuring instrument, the result who obtains is satisfactory.
Description of drawings
Fig. 1 is the structural representation of human body skin.
Fig. 2 is for realizing the measuring device sketch map of the method for the invention.
Fig. 3 is the sketch map that concerns of magnitude of voltage and moisture content value.
The specific embodiment
Describe the present invention in detail below in conjunction with accompanying drawing.
Figure 1 shows that the structure chart of human body skin, be followed successively by cutin skin 100 (thickness 5～10 μ m), epithelial tissue 200 (thickness 100～200 μ m), dermal tissue 300 (thickness 2～4mm) and hypodermis 400 from showing the lining.What wherein the skin health degree is had the greatest impact is the moisture of cutin skin 100, and the measured object of the present invention is exactly the moisture of cutin skin 100.
Fig. 2 is for realizing the measuring device sketch map of the method for the invention.Realizing a kind of measuring device of the method for the invention, mainly be made up of 4 parts and two electrodes, is respectively square-wave generator 1, electric capacity 2, resistance 3, amplifier element 4 and probe electrode.Pumping signal by below the square-wave generator 1 generated frequency 50KHz is input to tested skin area 5 via electrode S with pumping signal; The response signal of being returned by skin reflex receives by measurement electrode M.Square-wave generator 1, electrode S, tested skin area 5, electrode M, electric capacity 2, resistance 3 and ground are in sequential series, form the charge/discharge loop of a RC.The moisture of tested skin has determined the time constant in loop, this time constant is reflected by the both gut-nodes voltage of electric capacity 2 and resistance 3, the voltage signal of this point is big by 4 of follow-up amplifier elements, obtain sizeable measurement output voltage and gather by the AD conversion of back.
Described square-wave generator 1 can select for use a Single-chip Controlling buffer to realize.For example, can adopt the AVR singlechip chip of atmel corp, buffer has been with in the IO port inside of this single-chip microcomputer, can export bigger electric current during as output port; Square-wave generator 1 can directly be realized by the IO port of AVR single-chip microcomputer in the present invention, i.e. programming makes the voltage of single-chip microcomputer pin output carry out the variation of high and low level according to the frequency of setting, and the output signal that obtains is exactly a square wave excitation signal.And the general built-in AD analog-digital converter of AVR single-chip microcomputer can be gathered analog voltage signal, so just can directly receive the measuring-signal of being exported by amplifier element 4, and need not to add the AD conversion chip.By the setting of Single Chip Microcomputer (SCM) program, can realize easily that pumping signal is in the following frequency of 50KHz, and can come test adjustment frequency and the relation of measuring the skin area scope by changing concrete frequency values.
Two electrode S of measuring probe and M effectively are connected electrically to measuring circuit as long as guarantee with tested skin area in use.So if the metal material that is difficult for wear oxidation that uses no surface insulation layer to cover, and do not need strict configuration of electrodes.During use, two electrodes can adopt parallel modes of emplacement, and the shape of electrode can be rectangle, and the pole plate size is 1mm * 2mm, and the material of electrode can be selected golden Au for use.
Amplifier element is an analog comparater, adopt low frequency to amplify working method, the response signal that described measuring probe receives is carried out processing and amplifying, just can reach requirement of the present invention effectively as adopting analog comparater LM393, concrete circuit embodiment can be consulted the use document of LM393.Voltage amplification is the scope of 0～3V, and this voltage is gathered by the AD ALT-CH alternate channel of AVR single-chip microcomputer.
Fig. 3 is the sketch map that concerns of magnitude of voltage and moisture content value.Among the figure Vo be by measuring circuit obtain through amplified voltage value, the relating to parameters such as amplification of its numerical values recited and concrete instrument; M is a moisture content value.Point among the figure finds by demarcation, and absorbent filter sample utilization the inventive method is measured measuring voltage Vo, uses and dry the moisture content value that the method for weighing obtains correspondence, the fixed point among the figure that can draw thus.In this figure, the relation of magnitude of voltage and moisture content value is carried out match with straight line, this linear relationship is stored among the EEPROM of AVR single-chip microcomputer with diagrammatic form.
Describing below one adopts said apparatus to carry out the example that moisture of skin is measured.
At first, with the parallel placement with M of above-mentioned electrode S, the contact measured skin surface makes skin surface to be measured directly be connected electrically in the RC charging and discharging circuit, to detect the outer field equivalent eccentric electrical impedance value of cutin; Utilize pumping signal that the AVR single-chip microcomputer provides to electrode S and M square-wave signal for frequency 30KHz; The response signal of using analog comparater LM393 counter electrode S and M to receive is carried out processing and amplifying; Gather magnitude of voltage " 200mV " after the above-mentioned amplification by the AD conversion method, be stored in the AVR single-chip microcomputer.Search with the corresponding relation of moisture content value according to the magnitude of voltage of Fig. 3 and to obtain the corresponding moisture content value " 37% " of magnitude of voltage " 200mV ", Here it is measures the end product that need obtain, and can show by LCD afterwards.
From above-mentioned example as can be seen, compare with the general condenser type or the skin moisture measuring method of resistance-type, the measuring probe that the present invention uses does not need to keep labyrinths such as constant pressure, the requirement of excitation signal generator is lower, the amplifier section of follow-up measuring-signal only needs an amplifier element just can realize, and the skin area that the following measuring frequency of 50KHz can guarantee to measure is in the outer zone of cutin.So the present invention is better than general skin moisture measuring method on measuring principle, device architecture, realization cost.
Claims (5)
1. skin moisture measuring method is characterized in that:
Use two no surface insulation layer covered metal electrodes as measuring probe, with described measuring probe contact measured skin surface, make skin surface to be measured directly be connected electrically in the RC charging and discharging circuit, measuring object is and the outer field equivalent eccentric electrical impedance value of the contacted skin keratin of described measuring probe;
To the pumping signal that described measuring probe provides is square-wave signal below the frequency 50KHz;
Only use a circuit amplifier element to form amplifying circuit the response signal that described measuring probe receives is carried out processing and amplifying;
Gather magnitude of voltage after the above-mentioned amplification by the AD conversion method, be stored in the single-chip microcomputer, according to being stored in the magnitude of voltage in the single-chip microcomputer and the relation table of moisture content value, find out corresponding moisture content value again.
2. skin moisture measuring method according to claim 1 is characterized in that: described amplifying circuit adopts the low frequency of analog comparater to amplify working method, and the response signal that described measuring probe receives is carried out processing and amplifying.
3. skin moisture measuring method according to claim 1 is characterized in that: described pumping signal is produced and control by single-chip microcomputer.
4. skin moisture measuring method according to claim 1 is characterized in that: described two parallel placements of metal electrode, concentric-ring pattern are placed or interdigital is placed.
5. skin moisture measuring method according to claim 1 is characterized in that: described two metal electrodes are orthogonal.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2005100118752A CN100346743C (en) | 2005-06-06 | 2005-06-06 | Skin moisture measuring method |
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| CNB2005100118752A CN100346743C (en) | 2005-06-06 | 2005-06-06 | Skin moisture measuring method |
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| CN1686048A true CN1686048A (en) | 2005-10-26 |
| CN100346743C CN100346743C (en) | 2007-11-07 |
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| CNB2005100118752A Expired - Fee Related CN100346743C (en) | 2005-06-06 | 2005-06-06 | Skin moisture measuring method |
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Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103271739A (en) * | 2013-05-06 | 2013-09-04 | 清华大学 | Method and device for skin moisture measurement |
| CN103622694A (en) * | 2013-12-03 | 2014-03-12 | 中国科学院深圳先进技术研究院 | Skin moisture detector |
| CN104887228A (en) * | 2015-06-19 | 2015-09-09 | 河南山之峰信息科技股份有限公司 | Pulse type human body resistance detection device |
| CN105380646A (en) * | 2015-09-02 | 2016-03-09 | 深圳市哈里通实业有限公司 | Human body skin moisture detection system and method |
| CN105796106A (en) * | 2014-12-29 | 2016-07-27 | 昆盈企业股份有限公司 | External detection device and control method thereof |
| CN105982672A (en) * | 2015-03-04 | 2016-10-05 | 宽仕工业股份有限公司 | Skin detection method and device |
| CN106333644A (en) * | 2015-07-10 | 2017-01-18 | 武汉朗立创科技有限公司 | Skin parameter measurement circuit and method |
| CN107468216A (en) * | 2017-09-26 | 2017-12-15 | 江苏精微特电子股份有限公司 | Moisture of skin measuring circuit and moisture of skin measuring instrument |
| WO2018157369A1 (en) * | 2017-03-03 | 2018-09-07 | 蔡曜聪 | Physiological detection apparatus |
| CN108937933A (en) * | 2018-08-16 | 2018-12-07 | 歌尔科技有限公司 | A kind of skin detection instrument and its metal probe, moisture of skin calculation method |
| CN109145787A (en) * | 2018-08-07 | 2019-01-04 | 深圳市汇顶科技股份有限公司 | Detect the method, apparatus and terminal of moisture of skin |
| CN111556726A (en) * | 2017-12-27 | 2020-08-18 | 皇家飞利浦有限公司 | Determining moisture or lipid levels of skin |
| CN111595905A (en) * | 2020-05-25 | 2020-08-28 | 北京机械设备研究所 | Hydraulic pipeline bubble monitoring device and method |
| WO2024037286A1 (en) * | 2022-08-19 | 2024-02-22 | 厦门松霖科技股份有限公司 | Skin detection instrument having moisture detection function, and system, method and related device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US9326685B2 (en) | 2012-09-14 | 2016-05-03 | Conopco, Inc. | Device for evaluating condition of skin or hair |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01126535A (en) * | 1987-11-12 | 1989-05-18 | Kao Corp | Method and apparatus for measuring content of skin moisture |
| NO180024C (en) * | 1994-10-11 | 1997-01-29 | Oerjan G Martinsen | Measurement of moisture in the skin |
| US5588440A (en) * | 1995-08-10 | 1996-12-31 | Cowie; Jocelyn W. | Method and apparatus for locating and assessing soft tissue lesions |
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2005
- 2005-06-06 CN CNB2005100118752A patent/CN100346743C/en not_active Expired - Fee Related
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103271739B (en) * | 2013-05-06 | 2015-04-15 | 清华大学 | Method and device for skin moisture measurement |
| CN103271739A (en) * | 2013-05-06 | 2013-09-04 | 清华大学 | Method and device for skin moisture measurement |
| CN103622694A (en) * | 2013-12-03 | 2014-03-12 | 中国科学院深圳先进技术研究院 | Skin moisture detector |
| CN105796106A (en) * | 2014-12-29 | 2016-07-27 | 昆盈企业股份有限公司 | External detection device and control method thereof |
| CN105982672B (en) * | 2015-03-04 | 2021-07-06 | 林芳仪 | Skin detection method and skin detection device |
| CN105982672A (en) * | 2015-03-04 | 2016-10-05 | 宽仕工业股份有限公司 | Skin detection method and device |
| CN104887228A (en) * | 2015-06-19 | 2015-09-09 | 河南山之峰信息科技股份有限公司 | Pulse type human body resistance detection device |
| CN106333644A (en) * | 2015-07-10 | 2017-01-18 | 武汉朗立创科技有限公司 | Skin parameter measurement circuit and method |
| CN105380646A (en) * | 2015-09-02 | 2016-03-09 | 深圳市哈里通实业有限公司 | Human body skin moisture detection system and method |
| WO2018157369A1 (en) * | 2017-03-03 | 2018-09-07 | 蔡曜聪 | Physiological detection apparatus |
| CN107468216A (en) * | 2017-09-26 | 2017-12-15 | 江苏精微特电子股份有限公司 | Moisture of skin measuring circuit and moisture of skin measuring instrument |
| CN111556726A (en) * | 2017-12-27 | 2020-08-18 | 皇家飞利浦有限公司 | Determining moisture or lipid levels of skin |
| CN109145787A (en) * | 2018-08-07 | 2019-01-04 | 深圳市汇顶科技股份有限公司 | Detect the method, apparatus and terminal of moisture of skin |
| CN108937933A (en) * | 2018-08-16 | 2018-12-07 | 歌尔科技有限公司 | A kind of skin detection instrument and its metal probe, moisture of skin calculation method |
| CN108937933B (en) * | 2018-08-16 | 2023-10-13 | 歌尔科技有限公司 | Skin detector, metal probe of skin detector and skin moisture calculating method |
| CN111595905A (en) * | 2020-05-25 | 2020-08-28 | 北京机械设备研究所 | Hydraulic pipeline bubble monitoring device and method |
| WO2024037286A1 (en) * | 2022-08-19 | 2024-02-22 | 厦门松霖科技股份有限公司 | Skin detection instrument having moisture detection function, and system, method and related device |
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| CN100346743C (en) | 2007-11-07 |
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