3D-printed carrageenan-based nanocomposites for force-sensing applications

3D-P in ed Ca ageenan-Based Nanocomposi es o Fo ce-Sensing Applica ions Ve a M. Macedo, Nelson Pe ei a, Ca men R. Tubio, Ped o Ma ins, Ca los M. Cos a,* and Senen xu Lance os-Mendez 1. In oduc ion A apid echnological e olu ion is aking place linked o he In e ne o Thing (IoT) concep and he digi aliza ion o he soci- e y. [1] The IoT concep is based on he in e connec ion o physical and i ual objec s h ough senso s, ac ua o s, and he in e ne . [2] The in e connec ion be ween elec onic de ices allows he con inuous moni o ing, op imiza ion, and con ol in in elligen , dis ibu ed, sel -o ganizing and ene gy- cons ained ne wo ks, [2b] using communi- ca ion echnologies such as mobile and wi eless ne wo ks and iden ifica ion by adio equency, global posi ion sys ems (GPS), and Blue oo h sys ems, [2a] which c ea e a comple e sys em, ac ing as a whole. IoT is becoming widesp ead in a eas including secu i y, sma heal h sys ems, ag icul u e, anspo , indus y, and cons uc ion, among o he s. [2b] In he indus ial sec o , IoT allows op imi- za ion o p ocesses, e ec i e p oduc ion imes, and educed manu ac u ing cos s. [1] The me - i s o he IoT concep s ongly ely on he imp o emen in ma e ials and manu ac u ing echniques, ela ed o he Indus y 4.0 pa a- digm. [1,2] Sma ma e ials implemen a ion has become a co ne s one o he echnological e olu ion due o hei ac i e ole in imp o ing ma e ials esponse and in eg a ion. [3] Sma ma e ials can be desc ibed as a ma e ial ha senses en i onmen al changes and esponds, in a p edic able way, o he espec i e ex e nal s imulus. Depending on he sma ma e ial g oup, hey eac o di e en s imuli and p o ide a specific ou pu o ice e sa. [2a,4] Ac i e sma ma e ials g oups include piezoelec ic, piezo esis i e, magne o heological, V. M. Macedo, C. R. Tubio, S. Lance os-Mendez BCMa e ials Basque Cen e o Ma e ials, Applica ions and Nanos uc u es UPV/EHU Science Pa k 48940 Leioa, Spain N. Pe ei a, P. Ma ins, C. M. Cos a, S. Lance os-Mendez Physics Cen e o Minho and Po o Uni e si ies (CF-UM-UP) Uni e si y o Minho 4710-053 B aga, Po ugal E-mail: cmscos a@fisica.uminho.p The ORCID iden ifica ion numbe (s) o he au ho (s) o his a icle can be ound unde h ps://doi.o g/10.1002/adem.202201806. © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley- VCH GmbH. This is an open access a icle unde he e ms o he C ea i e Commons A ibu ion-NonComme cial License, which pe mi s use, dis ibu ion and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed and is no used o comme cial pu poses. DOI: 10.1002/adem.202201806 N. Pe ei a Cen o ALGORITMI Uni e si y o Minho Campus de Azu ém, 4800-058 Guima ães, Po ugal P. Ma ins, C. M. Cos a, S. Lance os-Mendez Labo a o y o Physics o Ma e ials and Eme gen Technologies (LapMET) Uni e si y o Minho 4710-057 B aga, Po ugal C. M. Cos a Ins i u e o Science and Inno a ion o Bio-Sus ainabili y (IB-S) Uni e si y o Minho 4710-053 B aga, Po ugal S. Lance os-Mendez Ike basque Basque Founda ion o Science 48009 Bilbao, Spain Technological de elopmen is leading o an exponen ial g ow h in he imple- men a ion o senso s and ac ua o s whe e he conce n abou en i onmen al p oblems is also ocusing on elec onic was e (e-was e), which is composed o haza dous ma e ials, co esponding o a la ge pa o u ban was e, and has a s ong en i onmen al impac . The e o e, mo e en i onmen ally iendly elec- onic componen s a e equi ed, na u al polyme s being a sui able app oach o sol e o a enua e hose p oblems. This wo k epo s on a bio-based polyme , ca ageenan, embedded wi h dielec ic ba ium i ana e (BTO) nanopa icles o ailo he elec ical esponse. The inclusion o he fille induces sligh modifi- ca ions in he he mal cha ac e is ics and on he physicochemical p ope ies o he polyme ma ix. On he o he hand, he mechanical and dielec ic p ope ies imp o e wi h he addi ion o BTO and a high dielec ic cons an o ε 013 000 is ob ained o he composi e wi h 20 w % BTO con en . The inc ease o he dielec ic cons an is accompanied by a high AC elec ical conduc i i y, leading o a high- ε 0–high-loss ma e ial. The 20 w % BTO composi e is used o p oduce a o ce measu ing senso , due o he highes dielec ic esponse. The unc ional esponse o he sensing sys em shows good s abili y o e cycling. RESEARCH ARTICLE www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (1 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH magne oelec ic, shape memo y, elec o heological, ch omic, sel -healing, and pH-sensi i e ma e ials, among o he s. [5] Since hese ma e ials possess a g ea capabili y o espond upon an ex e nal s imulus, hey a e excellen o sensing applica ions. Fe oelec ic ce amic–polyme composi es a e examples o sma ma e ials, since combine he bes o he e oelec ic ce amic p ope ies (high dielec ic and piezoelec ic coe ficien s, low dielec ic and mechanical losses and good he mal s abili y) wi h he ad an ages o he polyme ma ices (low densi y, flexibili y, excellen in eg abili y and p ocessable by addi i e manu ac u ing echniques), [6] which make i highly sui able o a la ge a ie y o sensing, elec ic powe and elec onics sys ems. [7] In his a ea, he p oduc ion o senso s based on sma ma e ials has ypically elied in syn he ic polyme s, as hey p o ide an e ficien way o achie e he desi ed p ope ies, h ough hei chemical and s uc u al modifica ion. Howe e , elec onic equipmen is mass p oduced, leading o a s ong inc ease o he so-called elec onic was e (e-was e). I e-was e is no managed p ope ly, i can lead o con amina ion by oxici y and heal h isks, comp omising he su ounding communi y. [8] E-was e has a po en ial o eco e aluable ma e i- als as i on, aluminum, coppe , gold, sil e , and a e ea h me als; ha is why i is globally ecognized as a esou ce o hese elemen s/ma e ials. [9] The ecycling o me als om elec onic de ices may educe he need o mining i gin ma e ials. None heless, e-was e collec ion a es and poo ecycling o ine - ficien end p ocessing o elec ical o elec onic equipmen , and consequen ly hese aluable esou ces a e was ed. [9a] Thus, a di e en s a egy mus be implemen ed. In o de o achie e mo e sus ainable sma ma e ials and o de elop a he same ime mo e sus ainable enginee ing p inciples, na u al polyme s can be used as an al e na i e o syn he ic ones. The ad an age o na u al polyme s is hei (bio)deg adabili y, non ox- ici y, and he possibili y, in some cases, o be p ocessed by addi- i e manu ac u ing wi h wa e as a sol en . [10] In elec onic echnologies, na u al polyme s can acili a e he ecycling p o- cess due o deg adabili y. They can also lead o less oxic compo- nen s which a e also biocompa ible, pa icula ly ele an o wea able senso s. [10] The wo main ypes o na u al polyme - based ma e ials mo e sui able on elec onic applica ions a e poly- saccha ides (chi osan, aga ose, A abic gum, dex an, hyalu onic acid, algina e, ca ageenan) and p o eins (albumin, gela ine, soy, and collagen). [11] Ca ageenan is a na u al polyme ha has shown g ea po en- ial o se e al applica ions, including sma packaging, [12] d ug deli e y, [13] and biomedicine. [14] Ca ageenan is a na u al sul a ed and anionic polysaccha ide (ca bohyd a e) ex ac ed om he mul icellula wall o ce ain species o ed algae sea- weeds o he Rhodophyceae amily such as Chond us c ispus, Giga ina, Euchuema, and Hypnea. Ca ageenan exis s in la ge abundance in na u e a low cos . [15] Usually, na u al polysaccha ides a e hyb ids and con ain epe i i e disaccha ide uni s o se e al ca ageenan ypes a ached in a single-polyme chain. [16] Depending on he numbe and posi ion o sul a e g oups in he disaccha ide epea ing uni , h ee main ypes o ca ageenan can be ound: kappa (κ), io a (ι), and lambda (λ), whe e i s sul a e con en is 20%, 33%, and 41% (w/w), espec i ely. [11,13,15b,17] Ca ageenan wi h highe le els o sul a ion ends o dec ease gel s eng h and solubili y empe a u e. [15b] This is he eason o selec ing io a (ι)-ca ageenan o a la ge a ie y o applica ions, since i s sul a ion is an in e media e alue. [18] Ca ageenan is a na u al polyme ha has shown g ea po en- ial o se e al applica ions, including sma packaging, [12] d ug deli e y, [13] biomedicine, [14] uel cells, [19] elec och omic de ices, [19] and solid polyme elec oly es. [16] As ep esen a i e examples, a polyme –sal complex based on ι-ca ageenan and ammonium b omide (NH 4 B ) has been p oduced by solu ion- cas ing me hod, leading o a maximum ionic conduc i i y o 1.46 10 5 Scm 1 and an elec ochemical s abili y window o 2.1 V. [20] NH 4 NO 3 wi hin ι-ca ageenan has been applied o elec ochemical de ices [19] and solid polyme elec oly es ha e been de eloped wi h ι-ca ageenan as polyme hos and li hium chlo ide (LiC) as fille , leading o a high oom empe a u e conduc i i y o 5.33 10 3 Scm 1 o he 1.0 g ι-ca ageenan: 0.3 g LiCl sample. [16] The p ope ies ha d ew a en ion in ca ageenan o be used as a polyme ma ix o addi i e manu ac u ing echnolo- gies, in addi ion o i s eco iendly beha io and being soluble in wa e , we e i s heology and s ong gel p ope ies a e cooling. [11,15b,17,21] Owing he capabili y o c ea e a wa e - e aining hyd ogel, ι-ca ageenan is sui able o being used in 3D p in ing echni- ques. [22] Ne e heless, despi e hei in e es ing p ope ies, he e a e also limi a ions in e ms o mechanical and elec ical p ope ies o some applica ion a eas. [23] Thus, in mos na u al polyme s, nanopa icles a e being used o de elop polyme com- posi es, allowing o in oduce and/o une specific p ope ies o he ma e ial by combining hei indi idual p ope ies o polyme and fille . [23b] Ba ium i ana e (BTO, BaTiO 3 ) is cha ac e ized by high dielec ic esponse and ionic conduc i i y cha ac e is ics and appea s o be a good candida e o nex gene a ion o ma e- ials wi h high-ε0–high-loss ma e ial, in combina ion wi h na u al polyme s. [24] BTO is a e oelec ic ma e ial, wi h high dielec ic cons an and spon aneous pola iza ions and low dielec ic losses. [25] Despi e i s po en ial in e es o uning polyme ma ix elec ical esponse, no s udies ha e been epo ed ega ding ca ageenan composi es wi h BTO nanopa icles, in any o ca ageenan ypes. The combina ion o ca ageenan/BTO and hei p ocessabili y by addi i e manu ac u ing, mo e p ecisely by di ec ink w i ing (DIW), can allow a new gene a ion o elec oac i e ma e ials wi h educed ma e ial was e du ing p ocessing and imp o ed sus ain- abili y due o he bio-based o igin o he polyme ma ix. [26] In pa icula , DIW allows o de elop bo h simple and complex cus- omizable senso designs o imp o e de ice in eg a ion, while being a scalable, low-cos , sus ainable, and high-accu acy p in - ing echnology. [27] Thus, his wo k p esen s a new composi e o ι-ca ageenan wi h BTO nanopa icles, p ocesses by 3D p in ing, in o de o de elop a dielec ic high ε0–high loss ma e ial, op imized o ouch sensing applica ions. www.ad ancedsciencenews.com www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (2 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH 15272648, 2023, 11, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/adem.202201806 by Uni e sidade Do Minho, Wiley Online Lib a y on [18/02/2025]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License 2. Expe imen al Sec ion 2.1. Ma e ials Io a-ca ageenan was pu chased om Al a Aesa . Ul apu e wa e was ob ained om a Milipo e-Q sys em. Ba ium i ana e (BTO, BaTiO 3 ), wi h 100 nm pa icle size and he su ac an T i on X-100, we e pu chased om SkySp ing Nanoma e ials and Sigma-Ald ich, espec i ely. 2.2. Sample P epa a ion BTO nanopa icles in di e en fille con en s (nea ca ageenan sample, 0, 1, 5, 10, 20 and 40 w %) we e dispe sed o 3 h in a mix u e o ul apu e wa e wi h he su ac an i on X-100 (0.01 w %), p e iously homogenized in an ul asound ba h (ATU, model no. ATM40-3LCD, 50 W) o 1 h o p omo e BTO nanopa icles dispe sion. Fu he , 3 w % o ca ageenan was added in o he solu ion and s i ed o ano he 3 h a 150 pm. The main s eps o he composi e o ca ageenan/ BTO nanopa icle p oduc ion a e desc ibed in Figu e 1a. 2.3. P in ing P ocess The p oduced gel was in oduced in o he sy inge and, in o de o emo e he bubbles, he sy inge was isola ed wi h pa afilm in bo h edges (so ha he gel does no leak) and placed in o a cen- i uge (MRC Lab) o 15 min a 2500 pm. The sy inge wi h ee bubbles gel was placed in he biop in e (Single Head 3D Biop in e - 3D Cul u es Tissue Sc ibe, 10 mL nozzle) and, a e an op imiza ion p ocedu e, he ollowing pa ame e s we e used o he p in ing p ocess: needle o 0.41 mm, space line o 0.51, o a oid o e lay o lines on he same plane, 30 mm s 1 p in ing speed, and 0.008 ex usion mul iplie . Then a 3D o m was p in ed, which esul ed in o a film, due he cu ing p ocess and wa e e apo a ion, wi h final hickness o 80 μm. Figu e 1b desc ibes he main p in ing s eps. 2.4. Samples Cha ac e iza ion The mo phology o he composi es was analyzed ia scanning elec on mic oscopy (SEM) using a Ca l Zeiss EVO-40 equipped wi h an ene gy-dispe si e spec oscopy (EDS) de ec o . To e alua e he polyme s uc u e and possible in e ace bonding be ween polyme and fille , Fou ie - ans o m in a ed spec oscopy (FTIR) was pe o med in a Jasco FT/IR-4100 sys- em. Measu emen s we e pe o med a oom empe a u e, in he a enua ed o al eflec ion (ATR) mode, be ween 600 and 4000 cm 1 , using 64 scans a a esolu ion o 4 cm 1 . The mal p ope ies o he sample we e e alua ed by di e en- ial scanning calo ime y (DSC) using a Me le Toledo DSC 822e appa a us equipped wi h a sample obo unde ni ogen flow o 20 mL min 1 . The scans we e ca ied ou om 20 o 150 °C a a hea ing a e o 10 °C min 1 . The samples we e weighed and com- pac ed in an aluminum c ucible, wi h a small hole on he op. Figu e 1. Schema ic ep esen a ion o he expe imen al s eps o a) composi e solu ion p epa a ion and o he b) p in ing p ocess. www.ad ancedsciencenews.com www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (3 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH 15272648, 2023, 11, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/adem.202201806 by Uni e sidade Do Minho, Wiley Online Lib a y on [18/02/2025]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License The mog a ime ic analysis (TGA) measu emen s we e pe o med in a TGA/SDTA 851e Me e Toledo appa a us. The samples we e hea ed om 30 o 600 °C, a a a e o 10 °C min 1 , wi h a ni ogen flow a e o 50 mL min 1 . The oom- empe a u e mechanical p ope ies o he compo- si es we e e alua ed unde ensile s ess a a cons an de o ma- ion o 50 μms 1 wi h a load cell o 200 N in a Linkam Scien ific Ins umen s TST 360. Samples we e p epa ed in ec angula shape wi h dimensions o 20 mm 10 mm 80 μm. The esul s we e p o ided as he a e age o fi e specimens. Dielec ic measu emen s we e pe o med, in samples wi h he same hickness (80 μm) and elec ode a ea, by ob aining he capaci y, C, and he dielec ic losses, an δ, using a Quad ech 1920 induc ance–capaci ance– esis ance (LCR) p ecision me e , a oom empe a u e, in he 20 Hz–1 MHz equency ange and wi h an applied ol age o 0.5 V. In each composi e, ci cula gold elec odes o 5 mm diame e we e deposi ed in bo h sides in a magne on spu e ing SC502 spu e coa e . The eal pa o he dielec ic unc ion (ε0), an δ, and he eal pa o he elec ical conduc i i y (σ0) we e de e mined h ough he ollowing equa ions ε0¼C:d ε0:A(1) an δ¼ε00 ε0(2) and σ0ðωÞ¼ε0ωε00 ðωÞ(3) whe e Cis he measu ed capaci ance, ε 0 is he pe mi i i y o ee space, Ais he elec ode a ea (m 2 ), dis he hickness o samples (m), and ω¼2π is he angula equency. [28] 3. Resul s and Discussion 3.1. Mo phological Analysis The su ace mo phology o he samples was analyzed using he ep esen a i e SEM images p esen ed in Figu e 2. Fo nea ca ageenan (Figu e 2a), a homogeneous fla su ace wi h low oughness is ob ained. The addi ion o he fille s (Figu e 2b–d) leads o oughe su ace due o bo h he p esence o he fille s and, in pa icula , o he numbe o well-dis ibu ed agglome a es ha inc ease wi h inc easing fille con en , being pa icula ly e idenced o he sample wi h 40 w % BTO con en . EDS images om Figu e 2e–g confi m his ac by he iden ifi- ca ion o he dis ibu ion o ba ium in he samples (p esen ed in blue) co esponding o he nanopa icles loca ion. 3.2. Physical–Chemical, The mal, and Mechanical P ope ies FTIR-ATR spec a o nea ca ageenan and BTO/ca ageenan composi es wi h di e en BTO con en s a e shown in Figu e 3a. Fo nea ca ageenan, he ypical ib a ion bands a 805, 845, 905, 930, and 1070 cm 1 a e obse ed, ha co espond o he C─O─SO 3 bonds o 3,6-anyhyd ogalac ose in C2, C4, and C6 o he galac ose uni y and he C─O bond o 3, 6-anyhyd ogalac se, espec i ely. [20] Fu he , he abso p ion bands o galac ose g oups and S═O bond o sulpha e es e s we e de ec ed a 970–975 and 1240–1260 cm 1 , espec i ely. The C═O asymme ic s e ch/N–H de o ma ion and he OH/NH s e ch- ing a e iden ified a 1635 and 3400 cm 1 , espec i ely. [29] No significan a ia ions a e obse ed in he spec a, independen o he fille con en compa ed o he FTIR spec a o BTO nano- pa icles, indica ing ha he e a e no new bonds o s ong in e - ac ions be ween he fille and he polyme ma ix. The DSC measu emen s (Figu e 3b) e eal ha he endo he - mic peak co esponding o he in insic wa e emo al and glass ansi ion empe a u e o he polyme dec eases wi h inc easing BTO con en , anging om app oxima ely 100 °C o he p is ine polyme [19,30] o 80 °C o he composi e wi h 40 w %. F om TGA analysis (Figu e 3c), he fi s mass loss, ela ed o wa e e apo a ion, [31] occu ed a empe a u es a ound 25–100 °C. The mass loss dec eases wi h dec easing BTO con en , being pa - icula ly e iden o he 40 w % BTO con en sample. I can be associa ed o he mois u e encapsula ed in he polyme ma ix. The highe mass loss was eached a 200–250 and 300 °C, which is ela ed o he ca ageenan polyme ic backbone deg ada ion. [32] A he end o he es (600 °C), he amoun o composi es mass de ec ed is ound o be di ec ly p opo ional o he fille con en . Figu e 3d shows he s ess–s ain cu es ob ained by mechanical es s in he ensile mode o all samples. I is obse ed he ypical mechanical esponse o he ca ageenan polyme [33] and ha he addi ion o he BTO con en imp o es he mechanical p ope ies, he BTO nanopa icles ac as a mechanical ein o cemen , as well as he obse ed educed amoun o wa e which inc eases he s i ness. [34] This beha io is de ec ed o all fille con en s, e en he smalles ones. The composi es o 20 and 40 w % BTO con en seem o ha e an iden ical mechanical beha io (Figu e 3d). Young’smodulus was de e mined by he angen me hod in he elas ic egion [35] (inse o Figu e 3d), whe e he samples wi h 10 w % BTO con en showed highe Young’sModulus,yields eng h,and ul ima e/ up u e s eng h p obably due o be e dispe sion o he BTO nanopa icles. The inco po a ion o fille s in o a polyme ma ix ypically enhances i s mechanical s eng h ( igidi y, ha dness, ac u e oughness, among o he s) due he high su ace a ea- o- olume a io o he fille s, which imp o es he in e ac ion be ween bo h ma ix and fille and is di ec ly influenced by he fille ’s size, shape and dis ibu ion, concen a ion, and specific in e ac ion wi h he ma ix. [36] In his way, he mechanical p ope ies o ne ca ageenan a e imp o ed (Figu e 3b, inse o he Young modulus) o he composi es up o 10 w % BTO con en . Fo fille concen a ions abo e 10 w % BTO, he e is a dec ease in mechanical p ope ies, as la ge fille concen a ions lead o fille agglome a es (Figu e 2), ac ing as de ec s unde mechanical de o ma ion. 3.3. Dielec ic Beha io Figu e 4a shows he eal (ε0) pa o he dielec ic cons an o nea ca ageenan and BTO/ca ageenan composi es a oom www.ad ancedsciencenews.com www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (4 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH 15272648, 2023, 11, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/adem.202201806 by Uni e sidade Do Minho, Wiley Online Lib a y on [18/02/2025]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License empe a u e, as a unc ion o equency. F om Figu e 4a, i is obse ed ha ε0dec eases wi h inc easing equency, indepen- den o he BTO con en , co esponding o slow dipola mobili y. [28] A high dielec ic esponse is obse ed o nea ca ageenan, (Figu e 4a) due o he high hyd ogen bonds, pola g oups, and wa e con en , con ibu ing bo h o he dielec ic esponse (Figu e 4a) and o conduc i i y (Figu e 4b). I is obse ed ha ε0inc eases wi h inc easing BTO con en due o he inc eased mobile cha ge ca ie s and in e acial cha ge con ibu ions o he Maxwell–Wagne –Silla s (MWS) e ec . [28] This e ec is obse ed in Figu e 4c o ε0as a unc ion o BTO con en a 10 kHz. Figu e 4b shows he AC elec ical conduc i i y, σ0, alue as a unc ion o equency calcula ed om Equa ion (3) o all sam- ples, showing ha σ’inc eases wi h inc easing equency, due o he inc eased cha ge ca ie mobili y in localized s a es. In addi- ion, i is no iced ha he AC conduc i i y inc eases wi h BTO con en , as he inclusion o he fille s inc eases he in e acial and wa e e ec s. [37] Figu e 4c shows he ε0o he samples a 10 kHz as a unc ion o BTO con en a oom empe a u e. A linea beha io o ε0is obse ed as a unc ion o fille con en up o fille con en o 20 w % and a dec ease o he dielec ic esponse is obse ed o he 40 w % BTO samples, due o he la ge fille agg ega es, ha educe he wa e e ec . The highes dielec ic cons an o BTO/ca ageenan composi es is 13 000 o he sample wi h 20 w % BTO con en . Thus, i is e ified ha ε0inc eases wi h inc easing BTO con en due in e acial and space cha ge pola iza ion, he composi e wi h 20 w % BTO wi h he la ges dielec ic esponse a 10 kHz. Figu e 2. Su ace SEM images o nea ca ageenan a) and he composi es wi h di e en BTO con en s: b) 1 w %, c) 10 w %, and d) 40 w % o BTO. EDS mapping images o Ba (Ba ium, blue) o samples wi h e) 1 w % o BTO, ) 10 w % o BTO, and g) 40 w % o BTO. www.ad ancedsciencenews.com www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (5 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH 15272648, 2023, 11, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/adem.202201806 by Uni e sidade Do Minho, Wiley Online Lib a y on [18/02/2025]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License 3.4. Fo ce Senso De elopmen and Func ional Response Figu e 5 shows he schema ic ep esen a ion o he senso (a), i s wo king p inciple (b), and he ac ual image (c). A o ce senso has been de eloped wi h he BTO/ca ageenan composi e wi h 20 w % o BTO conside ing i s high dielec ic alue. The sample was placed be ween wo conduc i e PET/ITO films wi h a PET sepa a o . The geome y o he de el- oped senso allows he measu emen o a comp ession o ce based on a 200 μm ai gap, c ea ed by he sepa a o and he BTO/ca ageenan composi e wi h 20 w % o BTO. The gap educes i s size wi h he p essu e, which changes he dis ance be ween he wo elec odes, changing he elec ical esponse o he senso , measu ed as a capaci y signal. The esul s o Figu e 6a show he capaci y alue o he sample a a equency o 1 kHz while applying a o ce om 0 o 10 N (0–55 kPa) a 1 N s 1 . Figu e 6a,b shows he no malized capaci y a ia ion unde cyclic applied o ce o 80 and 70 (de ail) cycles, espec i ely. Figu e 6c shows he sensi i i y o he sample. I is shown ha he o ce senso p esen s good epea abili y o o e 80 cycles. Figu e 6c shows ha he sample p esen s good linea i y un il he 30 kPa ange, wi h a sensi i i y o 0.0667 kPa 1 ( he sensi i i y is defined as S=(ΔC/C 0 )/p, 1000 1500 2000 2500 3000 3500 4000 BTO (a) 40w .%BTO 1w .%BTO T ansmi ance / a. u. Wa enumbe / cm -1 C-O-C O=S=O -O-SO C-O C-H O-H 0w .%BTO 5w .%BTO 10w .%BTO 20w .%BTO 20 40 60 80 100 120 140 endo (b) Hea Flow / W.g -1 Tempe a u e / ºC 80 ºC 89 ºC 100 ºC 99 ºC 102 ºC 40w .% BTO 20 w .% BTO 10 w .% BTO 5 w .% BTO 1 w .% BTO 0w .% BTO 105 ºC 100 200 300 400 500 600 20 30 40 50 60 70 80 90 100 (c) Weigh / % Tempe a u e / ºC 0 w .% BTO 1 w .% BTO 5 w .% BTO 10 w .% BTO 20 w .% BTO 40 w .% BTO 0 4 8 1216202428 0 10 20 30 40 50 60 (d) S ess / MPa S ain / % 0 w .% BTO 1 w .% BTO 5 w .% BTO 10 w .% BTO 20 w .% BTO 40 w .% BTO Figu e 3. a) FTIR-ATR spec a, b) DSC scans, c) TGA he mog ams, and d) s ess–s ain mechanical cu es (inse : Young’s modulus as a unc ion o BTO con en in he composi es) o nea ca ageenan and BTO/ca ageenan composi es con aining di e en BTO con en s. 10 2 10 3 10 4 10 5 10 6 10 2 10 3 10 4 10 5 (a) / Hz 10 2 10 3 10 4 10 5 10 6 / Hz 0w .% BTO 1w .% BTO 5w .% BTO 10w .% BTO 20w .% BTO 40w .% BTO 1E-3 0,01 0,1 (b) 0w .% BTO 1w .% BTO 5w .% BTO 10w .% BTO 20w .% BTO 40w .% BTO ' / S.m -1 010203040 4000 6000 8000 10000 12000 14000 (c) w .% o BTO 10kHz Figu e 4. a) ε0and b) σ0 o nea ca ageenan and BTO/ca ageenan nanocomposi es. c) Va ia ion o he dielec ic cons an as a unc ion o BTO con en a 10 kHz. www.ad ancedsciencenews.com www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (6 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH 15272648, 2023, 11, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/adem.202201806 by Uni e sidade Do Minho, Wiley Online Lib a y on [18/02/2025]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License whe e Cand C 0 deno e he capaci y wi h and wi hou applied p essu e, and pdesigna es he applied p essu e), he signal s a - ing o sa u a e o highe comp ession o ces. Once cha ac e ized, he de eloped o ce senso was connec ed o an elec onic ci cui based on a mic ocon olle A duino Uno (Figu e 7a,b). The ci cui sends a con inuous signal a 1 kHz o one o he elec odes o he senso and eads he alue on he o he elec ode ha is connec ed o he mic ocon olle analog– o-digi al con e e (ADC). A digi al Bu e wo h low-pass fil e wi h a cu equency o 10 Hz was implemen ed in he mic ocon olle fi mwa e, in o de o fil e he high- equency signal, while lea ing he signal om he p essu e e en . Figu e 7c shows he da a ecei ed by he mic ocon olle ADC ha was sen o a g aphical use in e ace (GUI) c ea ed in QT C ea o , whe e he da a can be isualized in eal ime (see sup- plemen a y ideo). The esul s show good co ela ion wi h he p e ious es s using he LCR me e . The senso can de ec a fin- ge p essu e and quan i y an inc ease o dec ease in p essu e. In Figu e 5. a) Schema ic diag am o he senso , b) senso wo king p inciple, and c) pic u e o he ab ica ed o ce/ ouch senso . -10 0 10 20 30 40 50 60 P essu e / kPa 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -0,5 0,0 0,5 1,0 1,5 2,0 2,5 3,0 P essu e C/C 0 Time / s C/C0 -10 0 10 20 30 40 50 60 P essu e / kPa 500 550 600 650 700 750 -0,5 0,0 0,5 1,0 1,5 2,0 2,5 (b) (a) P essu e C/C 0 Time / s C/C 0 0 102030405060 -0,5 0,0 0,5 1,0 1,5 2,0 2,5 3,0 (c) C/C0 P essu e / kPa Mean+ SD Fi Figu e 6. a) BTO/ca ageenan composi e wi h 20 w % o BTO unde 80 cycles o comp ession wi h a ying p essu e om 0 o 55 kPa. b) Magnifica ion a ea o he cycles ( ec angle in a)) and c) sensi i i y o he sample. www.ad ancedsciencenews.com www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (7 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH 15272648, 2023, 11, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/adem.202201806 by Uni e sidade Do Minho, Wiley Online Lib a y on [18/02/2025]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License o de o isola e a ouch e en om he hand (p oximi y o he finge o he elec odes), a polylac ic acid (PLA) od was also used o es he p essu e de ec ion. The demons a ed simple-ci cui implemen a ion shows he e sa ili y o he de eloped senso o ouch/p essu e de ec ion applica ions. I is he fi s ime ha a o ce senso based on ca ageenan wi h BTO nanopa icles has been epo ed and i s beha io is compa able o senso s epo ed in he li e a u e based on composi es p oduced by syn he ic polyme s such as, ca bon nano ube/polydime hylsiloxane (PDMS), [38] MXene/ poly inylidene fluo ide, [39] and BTO wi h PDMS. [40] The dielec ic esponse o he BTO/ca ageenan nanocompo- si es as a o ce senso was demons a ed in a unc ional de ice, opening new a enues o he de elopmen o en i onmen ally iendly composi e ma e ials o elec onic applica ions. 4. Conclusion Ca ageenan-based composi es wi h BTO nanofille s ha e been de eloped by di ec ink w i ing o o ce-sensing applica ions. Fu he , he influence o BTO nanofille s con en , up o 40 w %, on he composi e physical–chemical p ope ies has been also add essed. The samples showed a compac mic os uc u e, he BTO fille being homogeneously dis ibu ed in o he ma ix and obse ing an inc ease in fille agg ega ion o he samples wi h la ge nanopa icle con en . The he mal p ope ies o he samples depend on BTO fille con en , T g alues, and endo he mic peak in ensi y, dec easing wi h inc easing fille con en . Mechanical and dielec ic p ope ies we e also a ec ed by he BTO con en . Mechanically, he bes sample was he one wi h 10 w % o BTO, ac ing as be e mechanical ein o cemen . Dielec ic p ope ies o he composi es we e gene ally imp o ed upon BTO addi ion. In pa icula , o he 20 w % BTO con en sample, he dielec ic cons an was 13 000, showing also an AC conduc i i y o 0.011 S m 1 a 10 kHz, being he e o e a high-ε0–high-loss ma e ial. Wi h espec o senso applica ion, a good epea abili y in he senso elec ical esponse has been ob ained wi h he 20 w % BTO sample o o e 80 cycling es s o o ce a ia ion be ween 0 and 10 N. A good linea i y has been ob ained o o ces up o 5 N ange (a ound 86.7 pF N 1 ), s a ing o sa u a e a highe comp ession o ces. In summa y, he de eloped BTO/ca ageenan composi es exhibi a sui able sensing esponse, hus allowing o de elop o ce senso s o sus ainable elec onics. 0102030405060708090100110120 200 300 400 500 600 (c) Value / a.u. Time / s (a) (b) Figu e 7. a) Pho og aphy o he elec onic ci cui and capaci i e senso , b) schema ic o he elec onic ci cui , and c) da a ecei ed om he elec onic ci cui when a p essu e e en occu s. www.ad ancedsciencenews.com www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (8 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH 15272648, 2023, 11, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/adem.202201806 by Uni e sidade Do Minho, Wiley Online Lib a y on [18/02/2025]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License Acknowledgemen s The au ho s hank he Fundação pa a a Ciência e Tecnologia (FCT) o financial suppo unde he amewo k o S a egic Funding g an s UIDB/04650/2020, UID/FIS/04650/2020, UID/EEA/04436/2020, and UID/QUI/0686/2020 and unde p ojec s POCI-01-0145-FEDER-028157 and PTDC/FIS-MAC/28157/2017 unded by na ional unds h ough FCT and by he ERDF h ough he COMPETE2020—P og ama Ope acional Compe i i idade e In e nacionalização (POCI). The au ho s also hank he FCT o financial suppo unde g an SFRH/BD/131729/2017 (N.P.) and con ac s unde he S imulus o Scien ific Employmen , CEECIND/03975/2017 (P.M.) and 2020.04028.CEECIND (C.M.C.). Financial suppo om he Basque Go e nmen Indus y Depa men unde he ELKARTEK p og am is acknowledged. The au ho s hank ech- nical and human suppo p o ided by SGIke (UPV/EHU/ERDF, EU). 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Mena d, Dynamic Mechanical Analysis: A P ac ical In oduc ion, CRC P ess, Boca Ra on, FL 1999. [36] N. Elshe eksi, A. Much a , C. Azha i, Polym. Polym. Compos. 2021,29, 484. [37] a) H. S. Dahiya, N. Kisho e, R. M. Meh a, J. Appl. Polym. Sci. 2007, 106, 2101; b) C. Liu, L. Zheng, L. Yuan, Q. Guan, A. Gu, G. Liang, J. Phys. Chem. C 2016,120, 28875; c) L. Zhang, P. Bass, Z.-Y. Cheng, Appl. Phys. Le . 2014,105, 042905. [38] J.-S. Kim, G.-W. Kim, Senso s 2017,17, 229. www.ad ancedsciencenews.com www.aem-jou nal.com Ad . Eng. Ma e . 2023,25, 2201806 2201806 (9 o 10) © 2023 The Au ho s. Ad anced Enginee ing Ma e ials published by Wiley-VCH GmbH 15272648, 2023, 11, Downloaded om h ps://onlinelib a y.wiley.com/doi/10.1002/adem.202201806 by Uni e sidade Do Minho, Wiley Online Lib a y on [18/02/2025]. See he Te ms and Condi ions (h ps://onlinelib a y.wiley.com/ e ms-and-condi ions) on Wiley Online Lib a y o ules o use; OA a icles a e go e ned by he applicable C ea i e Commons License