TECHNICAL INFORMATION FOR TG54160 an ISO9001 company Technical Information for Carbon Dioxide Sensors The Figaro TG54160 is anew solid electrolyte type sensor which offers miniaturization and long life. The TG54160 displays high selectivity to carbon dioxide. Also, the TO54160 displays good long term stability and shows excellent durability against the effects of high humidity through the application of innovative technology in the sensor's electrode design. 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SR aK Oh Un Ln de Keflability Gas Exposure Test High Temperature/Humidity Test Heat Cyle Test Low Temperature Test Heater On-Off Test Ethanol Exposure Test Effect of Exposure to High CO2 Concentration ........0......csecee 'o be bs oe ta 4g So OWT 5a a ee eee ee eee ee eee ee ee eee se eee eee eee eae ae anne nee se ee see eeeeneneames samen sant = ; OPERATING COMO TIONS IN WHICH PR ARO SENSORS ARE L&ED WILL VARY WITH EACH CUSTOMERS SPECIAC APPLICATIONS AGARO STRONGLY RECOMMENDS CONG UITING OUR TECHNICAL STAPF BERORE DEPLOYING FRG ARO SIENSCNRS IN YOU RAPP LECATION AMD, IN PARTICULAR, WHEN OUSTOMER'S TARGET CASES ARE MOT LISTED HEREIN. AG ARG CANMOT ASSUME ANY RESPONSIBILITY FOR ANY USE CXF ITS SENSORS IN A PRODUCT OR AP PLECATION FOR WHICH SENSOR HAS NOT BREN SPRCIRIC ALLY TESTED BY AR. AIR. fewsed (040%) ff & Sif wi Bub ap im Il th 7c oZ 78 BF GOR Z@ ol Hhit: FER PIED A B1006-1018 alte: 518033 Bin: O755-B9979118 89278609892 78860 fH: 07655-83279284 fjiit: wow. apel lesz, cem Aza: Sensor@apal losz. comTECHNICAL INFORMATION FOR TGS4160 1. Specifications 1-1 Fentures Tap View Betlom view (SareorEkmant) * High selectivity to carbon dioxide Low humidity dependency Small size Lang lite * * * Side view (Sensor Element) B: PL Healer F : Beaing Gass E> Counter Bactroda fAncdo] Sold Ekerrolyts Sanang Ekecirods (Cathode 1-2) Applications * Air quality contral * Fermentation process contral * C08 gas control for incubators 0 Oo SUS304 60 mesh Non-acwen Fabric Zeolbe Filter 1-3 Strecture Figure 1 shows the structure of TGS4160, The TGS4160 is a hybrid composed of a carbon dioxide sensing clement and aninternal thermistor. The CO2 sensing element consists of a cation (Na*) solid electrolyte formed between two electrodes together with a printed heater (Pt) substrate. The cathode , : Sansor Element (sensing element) consists of lithium carbonate and gold, while the anode (counter electrode) is made of gold. The anode is connected to sensor pin No.3 (S(+)") while the cathode is connected to pin Na4 Fig. 1 - Sensor structure (5(-)"). A Ptheater connected ta pins No.1 (H") and Noe (H") heats the sensing element. An internal thermistor connected to pins No.2 and No.5 detects the environmental temperature in order to compen: sate for the sensor's temperature dependency. SU5316 100 mesh Intemal Thermistor Lead Pins ; , ; Top View (TG541 80) Lead wires are made of Pt at (.lmm diameter, and epee these wires are spot welded to nickel pins. The sensor base is made ol polyethylene terephthalate reinforced with glass fiber. The internal cover is a double layer Thermistor & ol 1) mesh stainless gauze (SUS316). The cover is fastened to the sensor base with a nickel plated brass ring. External housing material consists ol reinforced polyamide resin. A layer of 60 Mesh stainless steel gauze (SUS 304) is used for the outside cover. The Fe space between the internal and outer covers is filled with adsorbent (zeolite) for the purpose of reducing the influence of interference gases. 0) Thenmistar Operational 4umipifier Iiput impedance 100G0 Bias current = Tp 1-4 Operation principle When the sensor is exposed to O02 gas, the following electrochemical reaction occurs: to | Cathodic reaction: 27Lit + CO8+ 1/208 + 2e = LisCOs Anodic reaction: 2Na + 1/20a+ 2e" = Naa Overall chemical reachon: LieCOa + 2Na* = Naz + 2Lit + CO2 Fig. 2- Basic measuring cine uit fevised @39N) a fe Se a) ue AB im Dl th 7 62 7 BF BOR 2 ol Ht: adi oe PrIEA A 1006-1018 Alaa: 518033 Big: O755-89279118/83278699/832 78860 fBL: 0755-63279283 fijdit: www. apollosz. cam Higa: Sensor@apal lasz. comTECHNICAL INFORMATION FOR TGS4160 Asa result of the electrochemical reaction, electro- motive force (EMP) would be generated according to NWernsts equation: Top view EMP = Ee-(Rx T) / (2F) in (Pico) e17.7410 where AVCOs): Partial pressure af (Oe, Ee : Constant value Ro: Gas constant T : Ter perature (Ky F: Faraday constant By monitoring the electromotive force (EMF) generated between the two electrodes, it is possible to measure COs, 60208 Groan Dect tl 1 | in 1-5 Basic nearing crcl | Figure 2 shows the basic measuring circuit for TGS4160. The sersor requires that heater voltage (WH) a be applied to the integrated heater in order to Bile wiow | [eoeos maintain the sensing element at the optimal temp- | | | l Ba4ie10 24.341.0 erature for sensing. The sensor's EMF should be ha don measured using an operational amplifier with high 1 1 impedance (more than WK) and low bias current (less than 1 pA} such as Texas Instruments model Na. TLC 271. Since the solid electrolyte type sensor functions asa kind of battery, its absolute EMF value would drift using this basic circuit. However, the change of EMP value (AEMF) maintains a stable relationship with the changes in CO2 concentration. Therefore, in order to obtain an accurate measure- ment af CO2, a special microprocessor tor signal processing should be used with TGS4160. A special Sar evaluation sensor module which performs the requ ir- ed signal processing (AM-4)is available from Figaro. Fig. 3 - Sensor dimensions See Technical Information of AM-+ for further details. White Dat 45 3 13" . afer pee Bottom view Nea NOTE: When the sensor is powered, the ep ical resistance value leh Circutt f&onerating condi bons of the internal thermistor is around &0k0 due to heat radiated from the heater. Therefore, the change ratio of thermistor resistance The ratings shown below should be maintained at (RT/RTo) should be used for compereating the temperature : . . dependency of TOS1160 instead of using the absolute res stance all times to insure stable sensor performance: a : value of the internal thermistor. Item Specification saber yoltaae (YHA 5 OY ae * : : Heater voltage WH Wott De 1-7 Specifications NOTE 1 Heater resistance (RET - room eng. 113+ 1.103 . Item Specification Heater current approx. 250A ; 7 EMF in 330ppm of CO2 220 ~ 490m Heater power consumption appro. 1.250 EMF (3350ppimnCO2) - : - : M- = 44 = 7ImV Resistance of internal thennister 1ookia + 33%, AEMEP EMF (33500ppm C02) 44~72m\ B constant of internal thermistor 3450 4 240 NOTE 1: Sensitivity characteristics are obtained under the . .. , , following standard test conditions: Operating conditions HC ~ 480C, 5 ~ 98 RH & . ; __, - (Sihondard fest condi ioaes Stoniec condi tiens 2PC ~ 480C, 5 ~ SARH Tenperavre aad hianidie: 2) 22C, 65 25% RA . . . - at e: VH =S540 057 BC Optimal detection concentration 300 ~ 3, 000ppamn fare cont Batis VR 20. OST BC og . Praieating periods 7 dinge ar gare weirder Shaidind Giancdl coding fevived (LiAN) 3 fe & Sw) Bok BB im Il th 7c oZ 78 BF GOR Z@ ol Thi: FEUD RM PIED XB 1006-1018 alte: 518033 Bin: O755-B9979118 89278609892 78860 fH: 07655-83279284 fajtit; www. apol losz, com Higa: Sensor@apeal losz. comfr & Sit we Buk aS Hitt: FEV PHILA AB 1006-1018 Mig: O755-892779118/83278699.832 78860 feliit: wew. apol loss. com TECHNICAL INFORMATION FOR TGS4160 Mechanical Strength: The sensor shall have no abnormal findings in its structure and shall satisfy the above electrical specifications alter the following performance tests: Withdrawal Force - withstand torce > 5kg in each direction Vibration - frequency-10--55Hz, amplitude- Lamm, repeating 1 min. sweep, duration-two hours, x--z direction Sbock - acceleration-lOOG, repeated 3 times, x-y-z direction 1-8 Ditterisions (see Fig. 3) 2. Basic Sensitivity Characteristics 2-1 Sensitivity to veriows gases Figure 4 represents typical sensitivity characteristics of TGS4160. The Y-axis is indicated as AEMF which is defined as tollows: AEMFaEMFI1 - EMF? wmiere EMPISEME itv SS) ppm of CO2 EMP2=EMFP tn Usted gas aeceniral aaa As shown by Figure 4, TGS4160 exhibits a very good linear relationship between AEMFP and CO2 gas concentration on a logarithmic scale. The sensitivity curve to CO2 show's asharpincrease in AEMF as CO concentration increases. In comparison, sensitivity ta CO and ethanol (C3H50H) are very low as evidenced by the relatively flat slope and low AEMF walues of the sensitivity curves for these gases. 2-2 Teniperatire dependency Figure 5 shows the temperature dependency af TGS4160. These charts demonstrate that while the absolute EMF value increases as the ambient temperature increases, the AEMP remains constant repardless of temperature change (actually, AEMF changes according to Nemst's law, but the degree of change would be negligible in the operating temperature range of -10~+50C). As a result, an inexpensive method for compensation af temperature dependency would be to incorporate an internal thermistor in the detection circuit. a0 = / 20 ye at 100 1000 10000 Gas Concentration (ppm) 40 AEMF (mv) Pig. 4- Sensitivity to various gases (AEMP = EMEP in 350 pen. C02 - EMP in listed concentration) 400 a7 ao EMF (mj qu) ARETE 8 AENF (ppm CO2 - 1000 ppm COBY 8 2-10 a 10 20 30 40 eo ao Temperature [C} Fig. 5- Temperature dependency (Absolute humidity=?.4dg H20/ke of air) Rewise df (44M) im Wi th YZ 7 FBO 2 ol faa: 518033 fBL: 0755-63279283 Hz: Sensor@apoal lasz. camTECHNICAL INFORMATION FOR TG54160 2-3 Hurnidity dependency Figure 6 shows the humidity dependency of TGS4160. As this figure illustrates, the sensor show's verysmall dependency on humidity tor both absolute EMF and AEMP values. 2-4 Heater voltage dependency Figure 7 shows the change in EMP at 350 ppm of CO2 according to variations in heater voltage (WH). Mate that 5.0+0.2 Vas a heater voltage must be maintained because variation in applied heater voltage will cause the sensor's characteristics to be greatly changed from those shown as typical in this brochure. 2-5 Gas response Figure shows the change pattern of absolute EMF values when the sensor is placed imta 1,000 and 2,400 ppm ot COe for 10 minutes before being returned ta normal air. The res porse time bo 0% of the saturated signal level is around two minutes while recovery to 0% af the base level is within 4 minutes. ER ini) EMF (my EMF (ri) 360 100 325 Th a o = - EMF (350ppm coz) B 300 Bo 7 z 5 278 4 * <T* 4 AEMF (250 ppm Goe2 - 1000ppn coz) 260 Oo 10 2 a0 40 ao Bo ro 40 Relative Humidity (354 Fig. &- Humidity dependency Arc) 400 230 a 280 a a0 {_s60ppm coe |__] 220 00 47 4B 4.8 6.0 61 52 6.3 Healer Voltage (vy Pig. 7 - Heater voltage dependency 360 350 B40 i ao PA s20 = > 1000ppm 310 ope is * 2000ppm =00 coe q 10 i] a0 40 0 Time fmiry Fig. 8 - Gas resporse speed fiewlsed (34%) ff & Sif wi Bub ap Hhit: FER PIED A B1006-1018 Mif: O755-89779118/83278699/ 83278860 fit; www. apol lesz, com Ma: 518033 ER: 0755-85279283 Higa: Sensor@apeal losz. com im Il th 7c oZ 78 BF GOR Z@ olTECHNICAL INFORMATION FOR TGS4160 2-6 Initial action aoa Figure 9 shows typical initial action of the sensors fr EMP, For purposes of this test, the sensor wasstored 300 unenergized in normal air for twomeonths after which [2s0ppm of Goa it was energized in clean air. 200 After energizing, the sensor's EMF increases regardless of the presence of gas, reaching to 90% of its final value in less than 10 minutes. Since the sensor's EMF value is less than 4% of its final value a during the first LO minutes, a special signal processing method (such as that described in Technical EMF (mm) 100 ; ; . 100 Information for AM-4) should be incorporated inte D oan too con pap iano applications using TG54160 in order ta prevent Cauley Tima (5e0.} function of the user's device during this period. Fig. 9- Initial action 2-7 Long-tenn characteristics 360 - 70 ; -y: ERE 5 0ppm Figure 10a shows long-term stability data for a Ceo teeta an TGS4160. The test samples were energized in normal air and under standard circuit conditions. These 280 - EMF (380 ppm COP. 2000 ppm 50 charts illustrate that while the absolute EMF values = 200 pm i a F displayed a slight decrease over time, AEMF values = | | = show stable characteristics for more than S(M) days. e180 ee | a Figure 10b shows the influence of unenergized no 20 storage an the sensor's long term stability. Test sn AEWF (350ppm C02. 700 ppm C02) io samples were stored unpowered in room air for more than 300 days. Sensars were intermittently measured o Q under standard test conditions (20C /65%RH) a a0 100 Oe (dope) oo 1 during the test. This chart also demonstrates that while absolute EMP values slighthy decrease over _ time, AEMP shows stability for over 300 days. Fig. 10a - Lang term stability As the charts presented in this section illustrate, to0 AEMEP show's stable long term characteristics. 360) 300 2-8 Life expectancy EE ee 260) B The end of life for TG54160 occurs when: = z a 200 = a. Absolute EMP value in clean air drops to Mim . AEME (350 ppm COR - 3500p C02) after energizing in clean air for 24 hours. sp b. AEMEF (350 ppm vs 3500 ppm of CO2) drops to less ire than 30m regardless of absolute EMF in clean air. aD The life expectancy of TG54160 strongly depends on o so i100 150 300 280 500 | ABO circuit and environmental conditions. By Time (cys) extrapolating the data in Figure Ia, the life expectancy of TGS4160 is approximately 2,000 days Fig. Lib - Effects of unpowered storage with continuous energizing at room temperature. on keng, berm stability fewied O34) 6 fe & Sw we) Bk BB im Wi th YZ 7 FBO 2 ol Hitt: FEV PHILA AB 1006-1018 Bisa: 518033 Bif: O755-892979118/83278699/832 78860 EH: 0756-83279284 faltit: www. apollosz. com Higa: Sensor@apoal losz. comTECHNICAL INFORMATION FOR TGS4160 3. Reliability 7 Decans =] Gas exposure test Ethybonzare Borer: Formal . . , aoa Figure 11 shows the effect on sensor characteristics hone of various gases. Sensors were energized and the wea AEMF value (air vs 1000ppm of CO2) prior to gas Mahone exposure was measured. After the exposure in gases repentane in 100 ppm of the test gas for 24 hours, the sensor ara rope 7 F F a. af creae Perec] i yrs was removed from the test gas and energized in a meliy, aperienores narmal air, After one hour elapsed, the COs Ansicre: wos : Bulylaoatotc: characteristics was again measured, Chioramaryane Hea nig Eth qd As these tests demonstrate, care should be taken to aetna minimize exposure to some kinds of gases (such as Lime chlorine compounds) which lower the sensor's ey pesto sensilvity. 1,2,4-4imeiny! boreone: . Ehand Rathan of Hesamethyidis korean: pediehioro berrons: Chord bromomatiars: 4.1.4 -4richborathare: oo Tetrach ora eihylare: Chharodfonm Trichioro ath yan HAG ia CRG 42 Refarance: 0 5 10 15 2m 25 a AEM (mv Pig. 11 - Effect on AEMP of exposure to other gases (AEMP = EMP fair - 1000ppim COe)) 3-2 High tenperaticre/hieidi ty test To show the ability of TGS4160 to withstand the " effects of high temperature and humidity, the sensor was subjected to a test condition of 40C /H"ERH. Unenergized test samples were subjected this 40 a0 condition for 1000 hours and then samples were = Ki bes a E measured under standard test conditions (20C! = AEM (EMF 350pprn GO2 - EME 1000ppm COZ) 5 65%RH), fi 0 Figure 12 show's that the TG54160 maintains stable characteristics even if the sensor is used in high " temperature and humidity conditions. i a a 400 a Time (hours) Fig. 12- High temperature and humidity test Revised 034%) 7 fe & Sw) Bok BB im Il th 7c oZ 78 BF GOR Z@ ol Hhit: FER PIED A B1006-1018 alte: 518033 Bin: O755-B9979118 89278609892 78860 fH: 07655-83279284 fajtit; www. apol losz, com Higa: Sensor@apeal losz. comHNICAL INFORMATION FOR TGS4160 3-3 Heat ayele test Figure 13 shows the effect of subjecting the TGS41460 to a heat cycle test. Unenergized sensors were subjected to a cycle of -25C for 30 minutes followed by 85C for 30 minutes, with this cycle being repeated more than Lk} times. The sensors were intermittently measured under standard test conditions (20C/ 65,RH) during the test. As these test results show, TOS4160 has sufficient durability against the severity of heat cycle conditions. 4 Low tenipernttiere best Figure 14 shows the results of exposing TGS4160 ta severe low temperature. Unenergized sensors were subjected to conditions of -20C for 1480 hours. Sensors were intermittently measured under standard test conditions (20C /65%RH) during the test. As these test results show that there i almost no influence by low temperatures on the sensitivity characteristics of TOS4160. aS Heater on-off cycle lest If the TGS4160 would be used for indoor air quality monitoring or a portable CO2 monitor, the sensor would be powered on and off frequently. Tosimulate such conditions, the sensor was subjected to a heater on-alf cyele by applying the specified heater voltage (5.0) ta the sensor for | hour, then being powered aff for 1 hour. Samples were subjected to this cycle IMM) times. Sensors were intermittently measured under standard test conditions (20C /65%RH) during the test. As Figure 15 shows, eyeling the heater on and olf demonstrates that heater on-off does not result in arvy appreciable change in the sensor's sensitivity characteristics. EME im) EMF (miv') EMF (iv) aon fen 240 MO 320 300 250 250 240 Revised Q340N) fr & Sit we Buk aS Hitt: FEV PHILA AB 1006-1018 Mig: O755-892779118/83278699.832 78860 feliit: wew. apol loss. com EMF iateem CO2 = 7" = aEMF (EMF 36pm GOd- EMF 1000ppm Coe) a 20 40 eo a0 100 1 # of cyckes Pig. 13 - Effect of heat cycle testing EMF S80ppm Coe fA = nT = S aEMF (EDIF 28flppm G08 - EMF 1000 ppm Coz) 0 200 400 600 B00 7000 1200 Tine (hours) Fig. 1a - Effect of low temperature exposure a0 _ as a0 EMF 350pm CO? = oF = nT = OS a EMF (EMF 280pprn CO. EME 1006ppm G2) a 10 Qo a0 400 80 Boo 1000 1200 1400 1600 Time (hours) Fig. 15 - Effect of heater on-off testing 5 im Wi th YZ 7 FBO 2 ol faa: 518033 fBL: 0755-63279283 Hz: Sensor@apoal lasz. camff & Sif wi Bub ap 3-6 Ethanol exposire test To eliminate the influence of interference gases such as an ethanol vapor, a zeolite filter is installed in the cap of TGS4160. To demonstrate the effectiveness of the zeolite filter, the sensor was exposed in 3% af ethanol gas fora period of 6) days. During this test, AEMF values of ethanol were measured. AEMF is detirved as follows: AEMFeaEMF1 - EMF? uvere EMPI=EMP in 350 ppm COP EMP2=EMP in 350 ppm O02 and 300>pm EtOH The results of the above test are shown in Figure 16. As the stable AEMF values show, the zeolite filter has sufficient ability ta eliminate the influence of interference gases over an extended period of time. 3-7 Effect of exposure to high CO2 concentration Figure 17 shows the sensor characteristics of TG54160 in high concentrations of CO2 This data suggests that TGS4160 can detect CO2 in excess of IMMER ppm. However, it should be noted that the AEMF values would likely devitae from their initial values after exposure to high concentrations of COz, This would occur due to a shift in the chemical equilibrium between the sensing electrode and CO2 gas, 4. Notes The tollowing cautions regarding storage and installation of TGS4160 should be observed ta prevent permanent damage to the sensor: I} Install {store indoors, avoiding dew condensation, silicone vapor, and exposure to alkaline metals (Na, Li, ebc.). 2) Avoid places where vibration or mechanical shock may occur. 3) The sensor should not be stored in high humidity or temperature conditions. Sensarsshould be stored in an aluminuim-coated sealing bag together with desiccant. 4) The sensor should be mounted on circuit board using manual soldering. AEMF (mv BE imi TECHNICAL INFORMATION FOR TGS4160 40 20 o -20 -40 o 100 200 300 400 500 6o0 oo Time (days) Fig. 16-Effectaf ethanal exposure 400 250 4 itm. a0) a | 250 1 hs. bot 200) 10 700 1000 10000 100000 C02 concentration (ppm Fig. 1? - Effect of exposure to high OC concentrations fiewired (304) Hhit: FER PIED A B1006-1018 Mif: O755-89779118/83278699/ 83278860 fit; www. apol lesz, com Fa he g im Il th 7c oZ 78 BF GOR Z@ ol 516033 f#H: 0755-83279283 BLA : Sensoar@apoal losz. camEe eee ee eee eet Figaro USA Inc. and the manufacturer, Figaro Engineering Inc. (together referred to as Figaro) reserve the right to make changes without notice to any products herein to improve reliability, functioning or design. Information contained in this document is believed to be reliable. However, Figara does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights, nor the rights of others. Figaro's products arenot authorized for use as critical components in life support applications wherein a failure or malfunction of the products may result in injury or threat to life. fe & Sw we) Bk BB im Wi th YZ 7 FBO 2 ol Hhik: Bev PIE AI 1006-1018 lta: 518033 Hid: OF55-85279118/832 79699832 78860 EH: 0756-83279284 faltit: www. apollosz. com Higa: Sensor@apoal losz. com