Skip to main content

Polymer Microfibers Incorporated with Silver Nanoparticles: a New Platform for Optical Sensing

A Correction to this article was published on 04 September 2019

This article has been updated


The enhanced sensitivity of up-conversion luminescence is imperative for the application of up-conversion nanoparticles (UCNPs). In this study, microfibers were fabricated after co-doping UCNPs with polymethylmethacrylate (PMMA) and silver (Ag) solutions. Transmission losses and sensitivities of UCNPs (tetrogonal-LiYF4:Yb3+/Er3+) in the presence and absence of Ag were investigated. Sensitivity of up-conversion luminescence with Ag (LiYF4:Yb3+/Er3+/Ag) is 0.0095 K−1 and reduced to (LiYF4:Yb3+/Er3+) 0.0065 K−1 without Ag at 303 K under laser source (980 nm). The UCNP microfibers with Ag showed lower transmission losses and higher sensitivity than without Ag and could serve as promising candidate for optical applications. This is the first observation of Ag-doped microfiber via facile method.


Up-conversion nanoparticles (UCNPs) after co-doping with lanthanides ions have drawn much attention due to application in imaging, laser materials, display technologies, and solar cells [1,2,3]. The low fluorescence emission efficiency of UCNPs can be caused by the small absorption coefficients of lanthanide ions. The nanoscale dispersion of metal nanoparticles in polymeric and inorganic substrates has triggered a great interest in novel physical, chemical, and biologic properties of the nanocomposite materials [4]. For potential applications of the further miniaturization of electronic components, optical detectors, chemical and biochemical sensors, and devices are exciting possibilities with metal nanoparticles. Additionally, the semiconductors have been used as sensitizers for widening absorption range, such as CdSe, CdS, PbS, WO3, and Cu2O [5, 6]. Among these semiconductors, Cu2O is an interesting candidate due to its narrow band gap of ~ 2.1 eV, non-toxicity, low cost and abundance but heterostructure of Cu2O/ZnO is a promising material structure. It leads to a functional intergration, novel interface effect's properties of Cu2O and ZnO material [7]. On the other hand, UCNPs depicts superior properties relative to semiconductor quantum dots for instance the absence of autofluorescence tissue penetrability near-infrared laser excitation, non-blinking, and high chemical stability [8]. The synthesis of lanthanide-doped materials with spherical nanoparticles and nanorods has been studied by many research groups [9]. The issue of UCNPs oxidation occurs at high temperature significantly which reduced their applications. To avoid oxidation, core/shell structure overcomes oxidation whereas SiO2 shell grows around nanocrystals. Nanocrystal integration on chip as microstructure light detector is difficult. Therefore, microtubes, quantum dot-doped nanofibers, and dye-doped polymer nanowires have been employed in microstructural optoelectronics technology after successful investigation [10]. Correspondingly, nanowires, microtubes, and nanofibers have been fabricated and utilized to discuss the thermal sensing behavior by different research groups [11, 12].

However, metal nanoparticles (MNPs) have been considered to enhance UCNPs efficiency. Different strategies including chemical modification, crystal structure, and local field adjustment of metal have been proposed to improve the efficiency and sensitivity [13]. Investigations on rare earth ion-doped luminescence materials for luminescence enhancement of metal nanostructure such as Er3+/Yb3+ co-doped bismuth-germinate glasses containing Ag nanoparticles and Er3+/Yb3+ co-doped β-NaLuF4 nanocrystals which are spin-coated over gold NPs have been reported with inconsistent results and high sensitivity [14]. Moreover, aggregation-induced emission (AIE) is a distinctive fluorescence phenomenon which suggested that few dyes can emit stronger fluorescence in their solid state than in dispersion solution [15,16,17]. Different mechanism including J-aggregate formation, conformational planarization, and twisted intramolecular charge transfer for the AIE phenomenon has been previously proposed by researchers [18,19,20,21,22]. Besides, materials with AIE characteristics have attracted more research attention for potential application in various field organic light-emitting diode, chemosensing, and bioimaging [23,24,25,26,27]. Especially, the preparation of AIE-active fluorescent organic nanoparticles has attracted attention recently. These materials containing AIE dyes could emit strong luminescence in physiological solution which effectively conquers the aggregation-caused quenching effect of fluorescent organic nanoparticles based on typical organic dyes [28, 29]. Although many strategies for the preparation of AIE-active fluorescent organic nanoparticles have been developed, the preparation of AIE-active through facile and effective multicomponent reaction (MCR) has received rarely attention due to mismatch with experimental data [30,31,32,33,34]. So, the unique AIE properties of dyes showed very promising for the fabrication of ultra-bright luminescent polymeric nanoparticles [35, 36].

In maximum experimental study, powder samples were used to perform the spectral measurements that increased the concerns regarding the influence of aggregation inter-reflection. Therefore, it is necessary to establish a facile and simple strategy to overcome the abovementioned drawbacks. Thus, Ag nanoparticles after co-doping with UCNPs and PMMA solution were used in microfibers to enhance the luminescence. However, no results have been described focusing on Ag co-doped UCNPs to microfibers (UCNPs-MF).

Herein, we present a facile method to prepare microfibers from UCNPs/PMMA with and without Ag solutions. Especially, the photoluminescence properties of Ag and absence of Ag co-doped microfibers are studied at various excitation point of microfibers. Moreover, UC luminescence characteristics of a microfiber is investigated by exciting 980 nm diode laser source at different temperature for the purpose of temperature sensing. The dependence of the integrated FIR on temperature is obtained and the experimental data can be fitted well with an exponential function. Thus, a single microfiber having transitions 2H11/2→4I15/2 and 4S3/2→4I15/2 levels at 522 and 541 nm is used to calculate the thermal sensitivities.

Experimental and Method Section


The silver (Ag) powder, chloroform, cyclohexane, NaOH, NH4F, and ethanol were purchased from Shanghai Chemical Company, China. These chemicals were of analytic grade and used without further purification.

Preparation of Tetrogonal-LiYF4: Yb3+/Er3+ Nanoparticles

UCNP (tetrogonal-LiYF4:Yb3+/Er3+) was prepared using thermal decomposition technique. The three-necked flasks of 100 mL were used which contain rare earth ions with LnCl3 (Ln=Lu, Yb, Er) having a molar ratio of 78:22:1, respectively. The solution includes 15 mL 1-octadecene (ODE) and 6 mL oleic acid (OA). The mixture was heated up to 150 °C to obtain a pellucid solution and cooled up to room temperature after eliminating oxygen and residual water. Four millimoles of NH4F and 2.5 mmol of NaOH were added slowly into a flask containing 10 mL solution of methanol. To confirm, fluoride was dissolved entirely by stirring process up to 30 min after that prepared solution was heated at 300 °C at a rate of 50 °C/min for 1 h under argon atmosphere. The precipitates were separated at the rate of 4000 rpm and cooled down to room temperature, washed with ethanol, and dried at 60 °C for 12 h.

Fabrication of Ag Co-doped Fibers

In a typical fabrication process, 0.003 g of Ag, 0.005 g of tetrogonol-LiYF4:22%Yb3+/1%Er3+, and 0.6 g of PMMA were mixed separately in 15 ml, 12 ml, and 18 ml of cyclohexane (C6H12) and chloroform (CHCl3) solution, respectively. Afterwards, the mixture of PMMA gradually dispensed into Ag and UCNP solutions and stirred for 30 min until a transparent solution was obtained. A fiber probe with a tip several microns in size was fabricated using the flame-heated drawing technique. After the mixed solution was dropped on the glass substrate, a fiber probe was then dipped into the mixed solution and withdrawn rapidly to fabricate the microfibers. The microfibers were then drawn and cut into small pieces, as shown in Fig. 1.

Fig. 1
figure 1

Fabrication process of Ag co-doped microfibers (a) Pulling of microfibers from PMMA+NPs+Ag solutions. b Cutting view of fabricated microfibers into small pieces

Spectra Measurement

Figure 2 demonstrates the experimental setup, to study the thermal and optical properties of microfibers. The microfibers were illuminated using an excitation source of 980 nm after depositing on a glass substrate. In order to measure the transmission losses of microfibers, ×20 objective (NA = 0.4) was used. The charge-coupled device (CCD, ACTON) camera was applied to obtain emission spectra of a microfiber, and ocean optics spectrometer was used to record the spectra for temperature-sensing measurement. The excitation of microfibers having different diameter was demonstrated with 980 nm laser source under 0.998 mW laser power to study microscopic thermal properties.

Fig. 2
figure 2

Experimental setup of wave-guiding phenomena

Results and Discussion

Structure and Transmission Properties

Phase purity and crystal structure of UCNPs were studied by applying X-ray diffraction (XRD, Rigaku Miniflex II) technique. The observed XRD peak patterns (Fig. 3a) are well indexed and in agreement with JCPDS card # 17-0874. Fig. 3(b) displays scanning electron microscopy (SEM, NOva Nano-SEM 650) images of a microfiber. One of the SEM image could be clearly seen (see the inset) which suggests that a microfiber has a uniform diameter, together with a smooth surface. For better resolution, we used transmission electron microscopy (TEM, Tecnai G2F30) and energy-dispersive X-ray analysis (EDS, Tecnai G2F30) to investigate individual Ag co-doped microfibers. Figure 3(c, d) shows TEM and EDS images, respectively, which confirm the strong evidence of uniform dispersion of Ag co-doped nanoparticles in a single microfiber.

Fig. 3
figure 3

Characterization process of LiYF4:Yb3+/Er3+ and Ag co-doped microfibers. a XRD of LiYF4:Yb3+/Er3+. b SEM of Ag co-doped microfiber. c TEM Of Ag co-doped microfiber. d EDS of Ag co-doped microfiber

Furthermore, X-ray photoelectron spectroscopy (XPS, Thermofisher Escalab 250Xi) was used to determine the successful incorporation of rare earth ions and Ag ions into the LiYF4 host material as shown in Fig. 4a–f. The XPS survey spectrum (Fig. 4a) shows the presence of Li, Y, F, Yb, Er, and Ag elements, and the peak at 55.25 eV can be assigned to the binding energy of Li 1s (Fig. 4b). The peaks observed at 158.08 eV (Fig. 4c) can be assigned to the Y 3d. The peak at 684.08 eV is attributed to the binding energy of F1s (Fig. 4d). The Yb 4d and Er 4d peaks (Fig. 4e) can be observed at 186.08 and 164.08 eV, respectively. The peak located at 359.08 eV is related to the binding energy of Ag 3d. This confirms the successful tridoping of Ag ions in LiYF4:Yb3+/Er3+ nanoparticles [37].

Fig. 4
figure 4

XPS a survey, b Li 1s, c Y 3d, d F 1s, e Yb and Er 4d, and f Ag 3d spectra of LiYF4:Yb3+/Er3+ NPs doped with Ag

Figure 5a shows Fourier transform infrared ray (FTIR, Nicolet50 NTA449F3) spectra of LiYF4:Yb3+/Er3+/Ag nanoparticles in the region 400–4000 cm−1. The studies were carried out in order to ascertain the purity and nature of nanoparticles. The peaks observed at 3452 cm−1 are may be due to O-H stretching and deformation. The bands at 2925 and 2848 cm−1 are associated to the asymmetric (uas) and symmetric (us) stretching vibration of methylene (−CH2) in the long alkyl of oleate molecule, respectively. The bands at 1566 and 1469 cm−1 can be assigned to the asymmetric (uas) and symmetric (us) stretching vibration of the carboxylic group, respectively. The spectra contain a peak at 1740 cm−1 due to C=O stretching vibration. The peak located at 1383 cm−1 corresponds to the C-H deformation vibration. The spectra also contain a peak at 910 and 669 cm−1 which is due to asymmetric stretching vibration and Ag-O deformation vibrations. It implies that FTIR results are in accordance with literature values [38].

Fig. 5
figure 5

a FTIR spectra of LiYF4: Er3+/Yb3+/Ag. b TGA spectra LiYF4: Er3+/Yb3+/Ag

To better understand the formation mechanism of Ag-doped microfibers, the thermal gravimetric analysis (TGA, NETZSCH) was conducted under a dry airflow from 293–393 K temperature. It is observed in Fig. 5b that a microfiber shows roughly two degradation steps. The first weight loss below 333 K could be attributed to loss of absorbed moisture/with the evaporation of trapped solvent (H2O or CHCl3) which is independent of sample composition. In graph, second weight loss happens from 333 K to 393 K which clearly represents the polymeric degradation process. Hence, Ag co-doped microfibers are polymer-based fibers which cannot stand with the temperature above 332 K [4].

In order to investigate individual optical properties of Ag-doped and undoped microfibers, laser light (980 nm) was employed from standard optical fiber to expose microfibers at oblique angles with respect to microfibers along axis. Figure 6a shows Ag co-doped microfiber (diameter ~ 6 μm) which was vertically excited under dark background with 980 nm and appeared that light spread in whole fiber because of Ag co-doped nanoparticles served as light transmitter. Conversely, Fig. 6d depicts without Ag co-doped microfiber (diameter ~ 6.5 μm) which was excited under dark background at top position with 980 nm laser source. It suggests that light cannot transmit equally in fiber due to high self-absorption and Rayleigh scattering phenomena. A microfiber (diameter ~ 6 μm) containing Ag co-doped NPs shows high green light emission than undoped Ag (diameter ~ 6.5 μm) having the same excitation of laser source under dark field. It is observe that bright end spots with no cluster having optical waveguides intend Ag co-doped microfiber absorbs near IR light and conduct alike toward end points. Moreover, Fig. 6b and c indicate that the Ag co-doped fibers having different diameters (~ 15.55 and ~ 9.15 μm) were excited at five different positions and exhibited green light emissions toward end points. Conversely, 980 nm laser source was applied to excite microfibers (without Ag NPs) at different five position having different diameters (~ 11.89 and 14.57 μm) which are shown in Fig. 6e–f, indicating less green light emission toward end points. The photoluminescence (PL) intensity of excited points against end spots was performed to elaborate the wave-guiding performance of microfibers (with and without Ag NPs) quantitatively [39]. We used adobe photoshop to convert spot images from RGB to gray styles, these gray values were evaluated by using MATLAB to characterize the corresponding intensities. After normalizing end points of photoluminescence intensities toward excited points, decay curves dependent of light propagation distance were obtained.

Fig. 6
figure 6

Photoluminescence images with different diameter of microfibers. ac Luminescence of Ag microfiber under dark background. df Excitation without Ag microfiber under black background

The transmission losses were measured using equation [40]:

$$ \frac{I_{\mathrm{endpoint}}}{I_{\mathrm{O}}}=\exp \left(-\upalpha \mathrm{d}\right) $$

Here, Eq. (1) shows that excited spots distance increases which results exponentially decrease of photoluminescence intensity. The relationship between photoluminescence intensity as a function of guiding distance of fibers (~ 15.55 and ~ 9.15 μm) with Ag NPs is shown in Fig. 7a, b. The emitted spectra were collected at five positions along the axis of microfibers which specifies the transmission of laser light with transmission loss coefficients α = 108.94 cm−1 and 91.05 cm−1. Conversely, Fig. 7c, d demonstrates the transmission loss coefficients of microfibers (without Ag NPs) having a diameter of 11.89 and 14.57 μm are about 231.72 and 274.84 cm−1, respectively. It is noteworthy that when the light is guided through Ag co-doped microfibers, it maintains small mode areas along the entire length of fiber. It enables strong interaction between light and Ag nanoparticles in cascade and leading to light transfer with high efficiency relative to microfibers without Ag. Ag co-doped nanoparticles have highly efficient photon to plasmon conversion in wave-guiding microfibers and facilitated enhanced light matter interactions within a highly localized area [41]. It accelerates opportunities for developing Ag-based photonic components and devices having high compactness, low optical power consumption, and reduced sizes. It is noted that simultaneous multiphoton excitation has been widely applied in fluorescent optical microscopy to show increased resolution and decreased specimen autofluorescence, as well as increased imaging depth. However, the low NIR absorption cross-section of multiphoton labels requires this technique to subject to the use of high-peak power ultrashort-pulsed laser. Principally distinct from simultaneous multiphoton process in dyes and QDs, which involves the use of a virtual energy level, photon up-conversion in UCNPs relies on the sequential absorption of low energy photons through the use of ladder-like energy levels of lanthanide doping ions. This quantum mechanical difference makes UCNP orders of magnitude more efficient than multiphoton process, allowing excitation with a low-cost continuous-wave laser diode at low-energy irradiance, typically as low as  10−1−2 [42]. The microfibers (UCNPs/PMMA/Ag) possess favorable transmission properties. Thus, the proposed microfibers (UCNPs/PMMA/Ag) have advantages of easy fabrication, low cost, strong plasticity, and unique optical properties of UCNPs such as large anti-stokes shift and abundant emission bands, further supporting their applications based on optical signal transmission, sensors, and optical components. Consequently, our estimated results of wave-guiding performances show well agreement with reported work [43, 44].

Fig. 7
figure 7

a, b Fitting lines between photoluminescence (PL) intensity and guiding distance of different diameter of microfibers with Ag co-doped under different excitation point. cd Fitting lines between photoluminescence (PL) intensity and guiding distance of different diameter of microfibers without Ag co-doped under different excitation point

Energy Levels and Thermal Effects

To elaborate the energy level diagram of UCNPs (Yb3+/Er3+), two dominant green emission bands around 522 and 541 and a red emission band centered at ~ 660 nm were observed. These observed emission lines are originated from 2H11/2 → 4I15/2, 4S3/2 → 4F9/2, and 4S3/2 → 4I15/2 of Er3+ ions, respectively. Energy levels 2H11/2 and 4S3/2 are populated by two photon processes. For population system of Yb3+/Er3+ ions, Yb3+ ions are excited by the pumping photons to populate consecutive three levels of Er3+ ions which are demonstrated as 4I11/2, 4F9/2, and 2H11/2 levels. It is observed that the population of 2H11/2 is obtained from given process 4I15/2 → 4I11/2 (Er3+): 4I11/2 → 2H11/2 (Er3+) levels. This phenomenon is caused by temperature excitation between thermally coupled levels. Therefore, the populations of 2H11/2 and 4S3/2 satisfy the Boltzmann statistics resulting in variation of population rates of 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 levels [45]. The mechanism of up-conversion process in Er3+/Yb3+ is illustrated in Fig. 8.

Fig. 8
figure 8

Energy level diagram of LiYF4:Yb3+/Er3+

The Ag co-doped UCNPs in fibers showed spectra with 980 nm laser source. The up-conversion (UC) luminescence is suitable for temperature-sensing applications. Therefore, Figs. 9a and 10a depicted the emission spectra of Ag and without Ag co-doped NPs which ranged from 400 to 750 nm under fiber laser excitation source, and spectra were collected with an average increment of 5 °C in temperature regime (303–348 K). Interestingly, by increasing temperature, the emission intensities were decreased significantly, therefore using 0.998 mW laser powers to avoid from thermal effects, clearly indicating the temperature-dependent behavior. While UCNPs-MF was heated in the temperature domain of 348–303 K, all photoluminescence was restored to original position whereas intensities showed significant reduction upon increasing the temperature. Therefore, this significant reduction in intensity is attributed to the escalation of variety of relative intensity corresponding to several multiphonon relaxation rates to diverse multiphonon relaxation rate. The luminescent intensity is significantly increased by introducing Ag in a microfiber under same experimental condition. Typically, heat energy is generated by laser light near irradiated area whose temperature is measured by applying thermal sensors, to estimate temperature of irradiated point with great accuracy. Fluorescence intensity ratio technique is a versatile technique widely used for temperature estimation. We discussed Ag and without Ag co-doped fibers upon temperature fluctuation; populations of 2H11/2 and 4S3/2 followed the Boltzmann distribution which resulted in variable population rates of 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2. Temperature sensing can be calculated using intensity ratio between 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions. Fluorescence intensity ratio (FIR) method can be expressed from the following equation [46]:

$$ \mathrm{FIR}=\frac{I_{522\mathrm{nm}\kern0.75em }}{I_{541\mathrm{nm}}}=C\exp \left(-\frac{\Delta E}{kT}\ \right) $$
Fig. 9
figure 9

a 3D up-conversion emission spectra of Ag co-doped microfiber under 980 nm excitation source. b Fitted curves between fluorescence intensity ratio and temperature. c Fitted data between sensitivity (K−1) and temperature (K) of Ag co-doped microfiber

Fig. 10
figure 10

a 3D up-conversion emission spectra without Ag under 980 nm excitation source. b Fitted curves between fluorescence intensity ratio and temperature without Ag. c Fitted data between sensitivity (K−1) and temperature (K) without Ag

Here, I522nm and I541nm are the relative intensities, C is the proportionality constant, ΔE is the energy gap between 522 and 540 nm, T is the absolute temperature, and k is the Boltzmann constant. Moreover, Figs. 9b and 10b display the variation of FIR with temperature; Eq. (2) determined that observed experimental data have a good linear fitting relationship. It is worth to investigate another key parameter that is the thermal-sensing mechanism of Ag- and without Ag-doped microfiber. Therefore, sensitivity (S) can be written as follows [47]:

$$ {S}_{\mathrm{a}}=\frac{\mathrm{FIR}}{\mathrm{dT}}=\mathrm{FIR}\left(\frac{\Delta E}{kT^2}\right) $$

Here, Sa is the absolute sensitivity of Ag and without Ag co-doped microfibers. The curves are exhibited in Figs. 9c and 10c, but digital values (FIR, ΔE, and k) for Ag and without Ag are obtained by fitted curves presented in Figs. 9b and 10b. Maximum sensor sensitivities for LiYF4:Yb3+/Er3+ and LiYF4:Yb3+/Er3+/Ag demonstrated to be 0.0065 and 0.0095 K°1 at 303 K, respectively. The optical temperature sensor’s sensitivities in different host materials are listed in Table 1. Although other sensitivities have a higher value as compared to without Ag UCNPs, LiYF4:Yb3+/Er3+/Ag is superior to host materials.

Table 1 The sensitivity values of optical temperature sensors in different host materials

This may be linked to the highest sensitivity among other host materials, as displayed in Table 1. Furthermore, we observed that sensitivity of LiYF4:Yb3+/Er3+/Ag at 303 K is also higher than LiYF4:Yb3+/Er3+ manifested to a highly efficient photon to plasmon conversion of Ag nanoparticles in microfibers. The Ag co-doped microfibers are intrinsically immune to photobleaching which provided high stability dopant for optical sensing. It suggests that Ag co-doped fibers due to significant sensing properties are suitable for temperature recognition. As a result, the utilization of Ag nanoparticles in a microfiber is beneficial to increase the luminescence and to tailor thermal sensing properties, suggesting a promising sensitive temperature sensor.


In summary, tetrogonal-LiYF4:Yb3+/Er3+ were prepared via thermal decomposition method and fibers were fabricated after co-doping PMMA solution with Ag and UCNPs. Successful Ag incorporation in UCNPs was supported through SEM, TEM, EDS, XPS, FTIR, and TGA analysis. The Ag co-doped polymer microfibers with a wave-guiding excitation approach and demonstrated potential use in thermal sensor were investigated. The intensity-dependent temperature sensitivity of Ag microfiber (0.0095 K°1) is higher than undoped Ag (0.0065 K°1) at 303 K, proposing Ag-doped microfibers are potential candidates for upgrading intensity-based temperature sensitivity at room temperature, which opens up new opportunities for developing compact photonic and plasmonic devices with low optical power. In the development of a newly employed method of microfibers with specified properties, significant improvements in up-conversion enhancement may be possible, leading to a more efficient up-converter, thereby enabling many of the technological applications of these materials.

Availability of Data and Materials

All data are fully available without restriction.

Change history

  • 04 September 2019

    Please note that following publication of the original article [1], these three sentences have been removed from the Background section of the article.



Joint committee on powder diffraction standards


Charge-coupled device


Up-conversion nanoparticles microfibers





Ln3+ :

Trivalent lanthanide ions

LiYF4:Er3+/Yb3+ :





Rare earth ions


X-ray diffraction


Transmission electron microscope


Scanning electron microscope


Energy dispersive X-ray spectroscopy


X-ray photoelectron spectroscopy


Fourier transform infrared rays


Thermal gravimetric analysis


Fluorescence intensity ratio


Energy difference


Absolute sensitivity


  1. Elizabeth D, Lambertus H, John R, Roger M (1996) A three-color, solid-state, three-dimensional display. Sci 276:1185–1189

    Google Scholar 

  2. Yi G, Lu H, Zhao S, Ge Y, Yang W, Chen D, Guo L-H (2004) Synthesis, characterization and biological application of size-controlled nanocrystalline NaYF4:Yb,Er infrared-to-visible up-conversion phosphors. Nano Lett 4:2191–2196

    CAS  Article  Google Scholar 

  3. Jian Y, Yuxue L, Duanting Y, Hancheng Z, Chunguang L, Changshan X, Li M, Xiaojun W (2016) A vacuum-annealing strategy for improving near-infrared super long persistent luminescence in Cr3+ doped zinc gallogermanate nanoparticles for bio-imaging. Dalton Trans 45:1364–1372

    Article  Google Scholar 

  4. Xin W, Huiqing F, Pengrong R, Huawa Y, Jin L (2012) A simple route to disperse silver nanoparticles on the surface of silica nanofibers with excellent photocatalytic properties. Mater Res Bull 47(7):1734–1739

    Article  Google Scholar 

  5. Xinwei Z, Huiqing F, Yuming T, Mingang Z, Xiaoyan Y (2012) Chemical bath deposition of Cu2O quantum dots onto ZnO nanorod arrays for application in photovoltaic devices. RSC Adv 5(30):23401–23409

    Google Scholar 

  6. Xiaohu R, Huiqing F, Chao W, Jiangwei M, Hua L, Mingchang Z, Shenhui L, Weijia W (2018) Wind energy harvester based on coaxial rotatory freestanding triboelectric nanogenerators for self-powered water splitting. Nano energy 50:562–570

    Article  Google Scholar 

  7. Xin W, Huiqing F, Pengrong R (2103) Self-assemble flower-like SnO2/Ag heterostructures: correlation among composition, structure and photocatalytic activity. Colloids Surf A 419:140–146

    Google Scholar 

  8. Gnach A, Bednarkiewicz A (2012) Lanthanide-doped up-converting nanoparticles: merits and challenges. Nano Today 7:532

    CAS  Article  Google Scholar 

  9. Wang X, Zheng J, Xuan Y, Yan X (2013) Optical temperature sensing of NaYbF4: Tm3+ @SiO2 core-shell micro-particles induced by infrared excitation. Opt Express 21:21596–21606

    CAS  Article  Google Scholar 

  10. Fujiwara M, Toubaru K, Noda T, Zhao HQ, Takeuchi S (2011) Highly efficient coupling of photons from nanoemitters into single mode optical fibers. Nano Lett 11:4362–4365

    CAS  Article  Google Scholar 

  11. O'Carroll D, Lieberwirth I, Redmond G (2007) Melt-processed polyfluorene nanowires as active waveguides. Small 3:1178–1183

    CAS  Article  Google Scholar 

  12. Rai V-K (2007) Temperature sensors and optical sensors. Appl Phys B 88:297–303

    CAS  Article  Google Scholar 

  13. Yuan G, Yuebo H, Peng R, Dacheng Z, Jianbei Q (2016) Effect of Li+ ions on the enhancement upconversion and stokes emission of NaYF4:Tb, Yb co-doped in glass-ceramics. J Alloy Compd 667:297–301

    Article  Google Scholar 

  14. Jun D, Zhenglong Z, Hairong Z, Mentao S (2015) Recent progress on plasmon-enhanced fluorescence. Nanophotonics 4:472–490

    Google Scholar 

  15. Jianzhao L, Jacky W-Y-L, Ben Z-T (2009) Acetylenic polymers: syntheses, structures, and functions. Chem Rev 11:5799–5867

    Google Scholar 

  16. Qing W, Qiang H, Meiying L, Dazhuang X, Hongye H, Xiaoyong Z, Yen W (2017) Aggregation-induced emission active luminescent polymeric nanoparticles: non-covalent fabrication methodologies and biomedical applications. Appl Mater Today 9:145–160

    Google Scholar 

  17. Liu C-M, Yanz H-L, Saijiao Y, Yongxiu L, Xiaoyong Z, Yen W (2019) Recent advances and progress of fluorescent bio-/chemosensors based on aggregation-induced emission molecules. Dyes Pigm 162:611–623

    Article  Google Scholar 

  18. Ruming J, Meiying L, Tingting C, Hongye H, Qiang H, J T YW, Qian-yong C, Xiaoyong Z, Yen W (2018) Facile construction and biological imaging of cross-linked fluorescent organic nanoparticles with aggregation-induced emission feature through a catalyst-free aside-alkyne click reaction. Dyes Pigm 148:52–60

    Article  Google Scholar 

  19. Xiaoyong Z, Ke W, Meiying L, Xiqi Z, Tao L, Yiwang C, Yen W (2015) Polymeric AIE-based nano probes for biomedical applications: recent advances and perspectives. Nanoscale 7:11486–11508

    Article  Google Scholar 

  20. Xiaoyong Z, Xiqi Z, Bin Y, Meiying L, Wan L, Yi C, Yen W (2014) Polymerizable aggregation-induced emission dye-based fluorescent nanoparticles for cell imaging applications. Polym Chem 5:356–360

    Article  Google Scholar 

  21. Xiaoyong Z, Xiqi Z, Bin Y, Meiying L, Wanyun L, Yiwang C, Yen W (2014) Fabrication of aggregation induced emission dye-based fluorescent organic nano particles via emulsion polymerization and their cell imaging applications. Polym Chem 5:399–404

    Article  Google Scholar 

  22. Zi L, Meiying L, Ruming J, Qing W, Liu C-Mao, Y. W, Feng J-D, Xiaoyong Z, Yen W, (2017) Preparation of water soluble and biocompatible AIE-active fluorescent organic nanoparticles via multicomponent reaction and their biological imaging capability. Chem Eng J 308:527-534

    Article  Google Scholar 

  23. Zi L, Liu C-M, Meiying L, Qing W, Yiqun W, Xiaoyong Z, Yen W (2017) Marrying multicomponent reactions and aggregation-induced emission (AIE): new directions for fluorescent nano probes. Polym Chem 8(37):5644–5654

    Article  Google Scholar 

  24. Zi L, Meiying L, Ke WFD, Dazhuang X, Liangji L, Yiqun W, Xiao YZ, Yen W (2016) Facile synthesis of AIE-active amphiphilic polymers: self-assembly and biological imaging applications. Mater Sci Eng C 66:215–220

    Article  Google Scholar 

  25. Long H, Saijiao Y, Junyu C, Jianwen T, Qiang H, Hongye H, Yuan QW, Feng JD, Xiao YZ, Yen W (2019) A facile surface modification strategy for fabrication of fluorescent silica nanoparticles with the aggregation-induced emission dye through surface-initiated cationic ring opening polymerization. Mater Sci Eng C 94:270–278

    Article  Google Scholar 

  26. Ruming J, Meiying L, Hongye H, Liucheng M, Qiang H, Yuanqing W-Q-C, Jianwen T, Xiaoyong Z, Yen W (2018) Facile fabrication of organic dyed polymer nanoparticles with aggregation-induced emission using an ultrasound-assisted multicomponent reaction and their biological imaging. Chem Eng J 519:137–144

    Google Scholar 

  27. Junyu C, Meiying L, Qiang H, Long H, Hongye H, Fengjie D, Yuanqing W, Jianwen T, Xiaoyong Z, Yen W (2018) Facile preparation of fluorescent nanodiamond-based polymer composites through a metal-free photo-initiated RAFT process and their cellular imaging. Chem Eng J 337:82–90

    Article  Google Scholar 

  28. Hongye H, Meiying L, Ruming J, Junyu C, Liu CM, Yuan QW, Jian WT, Naigen Z, Xiaoyong Z, Yen W (2018) Facile modification of nanodiamonds with hyper branched polymers based on supramolecular chemistry and their potential for drug delivery. J Colloid Interface Sci 513:198–204

    Article  Google Scholar 

  29. Hongye H, Meiying L, Qing W, Ruming J, Dazhuang X, Qiang H, Yuanqing W, Fengjie D, Xiaoyong Z, Yen W (2018) Facile fabrication of luminescent hyaluronic acid with aggregation-induced emission through formation of dynamic bonds and their theranostic applications. Mater Sci Eng C 91:201–207

    Article  Google Scholar 

  30. Ruming J, Han L, Meiying L, Jianwen T, Qiang H, Hongye H, Yuanqing W, Qianyong C, Xiaoyong Z, Yen W (2017) A facile one-pot mannich reaction for the construction of fluorescent polymeric nanoparticles with aggregation-induced emission feature and their biological imaging. Mater Sci Eng C 81:416–421

    Article  Google Scholar 

  31. Ruming J, Meiying L, Cong L, Qiang H, Hongye H, Qing W, Yuanqing W, Qianyong C, Xiao YH, Yen W (2017) Facile fabrication of luminescent polymeric nanoparticles containing dynamic linkages via a one-pot multicomponent reaction: synthesis, aggregation-induced emission and biological imaging. Mater Sci Eng C 80:708–714

    Article  Google Scholar 

  32. Qian YC, Ruming J, Meiying L, Qing W, Dazhuang X, Tian J, Hongye H, Yuanqing W, Xiaoyong Z, Yen W (2017) Microwave-assisted multicomponent reactions for rapid synthesis of AIE-active fluorescent polymeric nanoparticles by post-polymerization method. Mater Sci Eng C 80:578–583

    Article  Google Scholar 

  33. Qian YC, Ruming J, Meiying L, Qing W, Dazhuang X, Jian W-T, Hongye H, Yuanqing W, Xiaoyong Z, Yen W (2017) Preparation of AIE-active fluorescent polymeric nanoparticles through a catalyst-free thiolyne click reaction for bioimaging applications. Mater Sci Eng C 80:411–416

    Article  Google Scholar 

  34. Jian WT, Ruming J, Peng G, Dazhuang X, Liucheng M, Guangjian Z, Meiying L, Fengjie D, Xiaoyong Z, Yen W (2017) Synthesis and cell imaging applications of amphiphilic AIE-active poly (amino acid). Mater Sci Eng C 79:563–569

    Article  Google Scholar 

  35. Yanzhu L, Liucheng M, Xinhua L, Meiying L, Dazhuang X, Ruming J, Fengjie D, Yongxiu L, Xiaoyong Z, Yen W (2017) A facile strategy for fabrication of aggregation-induced emission (AIE) active fluorescent polymeric nanoparticles (FPNs) via post modification of synthetic polymers and their cell imaging. Mater Sci Eng C 79:590–595

    Article  Google Scholar 

  36. Hongye H, Dazhuang X, Meiying L, Ruming J, Liucheng M, Qiang H, Qing W, Yuanqing W, Xiaoyong Z, Yen W (2017) Direct encapsulation of AIE-active dye with β cyclodextrin terminated polymers: self-assembly and biological imaging. Mater Sci Eng C 78:862–867

    Article  Google Scholar 

  37. Parthiban R, Prakash C, Seog WR, Jinkwon K (2013) Enhanced upconversion luminescence in NaGdF4:Yb,Er nanocrystals by Fe3+ doping and their application in bioimaging. Nanoscale 5:8711–8717

    Article  Google Scholar 

  38. Singho N-D, Lah N-A-C, Johan M-R, Ahmad R (2012) FTIR studies on silver-poly (methylmethacrylate) nanocomposites via in-situ polymerization technique. Int J Electrochem Sci 7:5596–5603

    CAS  Google Scholar 

  39. Niu N, Yang P, He F, Zhang X, Gai S, Li C, Lin J (2012) Tunable multicolor and bright white emission of one dimensional NaLuF4:Yb3+, (Ln= Er, Tm, Ho, Er/Tm, Tm/Ho) microstructure. J Mater Chem 22:10889–10899

    CAS  Article  Google Scholar 

  40. Beer (1852) Bestimmung der absorption desrothen lichts in farbigen flussigkeiten (determination of absorption of red light in coloured liquids). Ann. Phys. 86:78–88

    Article  Google Scholar 

  41. Wang P, Zheng L, Xia Y, Tong L, Xu X, Ying Y (2012) Polymer nanofibers embedded with aligned gold nanorods: a new platform for plasmonic studies and optical sensing. Nano let 12:3145–3150

    CAS  Article  Google Scholar 

  42. Heer S, Kompe K, Gudel H-U, Haase M (2004) Highly efficient multicolour upconversion emission in transparent colloids of lanthanide-doped NaYF4 nanocrystals. Adv Mater 16:2102–2105

    CAS  Article  Google Scholar 

  43. Muhammad K-S, Yundong Z, Lugui C, Lu L, Mehwish K-B, Hanyang L (2018) Dispersing upconversion nanocrystals in PMMA microfiber: a novel methodology for temperature sensing. RSC Adv 8:19362–19368

    Article  Google Scholar 

  44. Jiang S, Zeng P, Liao L-Q, Tian S-F, Guo H, Chen Y-H, Duan C-K, Yi M (2014) Optical thermometry based on up-converted luminescence in transparent glass ceramics containing NaYF4:Yb3+/Er3+ nanocrystals. J Alloys Compd 617:538–541

    CAS  Article  Google Scholar 

  45. Chengqi E, Yanyan B, Lan M, Xiaohong Y (2017) Tm3+ Modified optical temperature behavior of transparent Er3+-doped hexagonal NaGdF4 glass ceramics. Nanoscale Res Lett 12:402

    Article  Google Scholar 

  46. Muhammad K-S, Yundong Z, Muhammad U-K, Xiao S, Lu L, Hanyang L (2018) Upconversion thermometer through novel PMMA fiber containing nanocrystals. Opt Mater Express 8:332796–332804

    Google Scholar 

  47. Zheng H, Chen B-J, Yu H-Q, Zhang J-S, Sun J-S, Li X-P, Sun M, Tian B, Zhong H, Fu S-B, Hua R-N, Xia H-P (2014) Temperature sensing and optical heating in Er3+ single-doped and Er3+/Yb3+ codoped NaY(WO4)2 particles. RSC Adv 4:47556–47563

    CAS  Article  Google Scholar 

  48. Dong B, Cao B, He Y, Liu Z, Li Z, Feng Z (2012) Temperature sensing and in vivo imaging by molybdenum sensitized visible upconversion luminescence of rare earth oxides. Adv Mater 24:1987–1993

    CAS  Article  Google Scholar 

  49. Zou H, Wang X, Hu Y, Zhu X, Sui Y, Song Z (2014) Optical temperature sensing by upconversion luminescence of Er doped Bi5TiNbWO15 ferroelectric materials. AIP Adv 4:127157

    Article  Google Scholar 

  50. Muhammad K-S, Yundong Z, Muhammad U-K, Harse S, Muhammad I (2019) Optical thermometry probe via fiber containing β-NaLuF4:Yb3+/Er3+/Tm3+. Curr Appl Phys 19:739–744

    Article  Google Scholar 

  51. Xu W, Zhang Z, Cao W (2012) Excellent optical thermometry based on short wavelength upconversion emissions in Er3+/Yb3+ codoped CaWO4. Opt Lett 37:4865–4867

    CAS  Article  Google Scholar 

  52. Dey R, Rai V-K (2014) Yb3+ sensitized Er3+ doped La2O3 phosphor in temperature sensors and display devices. Dalton Trans 43:111–118

    CAS  Article  Google Scholar 

  53. Aihua Z, Feng S, Yingdong H, Feifei S, Dandan J, Xueqin W (2018) Simultaneous size adjustment and upconversion luminescence enhancement of β-NaLuF4:Yb3+/Er3+,Er3+/Tm3+ microcrystals by introducing Ca2+ for temperature sensing. CrystEngComm 20:2029–2035

    Article  Google Scholar 

Download references


We acknowledge the characterization contribution of Engr. Muhammad Zeeshan Farooq from the Department of Material Science and Engineering, Harbin Institute of Technology, China, and the hard work of each member in our group. The authors do not have any kind of funding for this study.

Author information

Authors and Affiliations



MKS and AR performed the whole experiments and wrote the manuscript. YZ provided the novel idea to carry out the experiment. AA participated in the analyzes of the results and discussion of this study. MI, KQ, MUK, and MJA revised the manuscript and corrected the English. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Yundong Zhang or Abdulaziz Alhazaa.

Ethics declarations

Competing Interests

The authors declare that they have no competing interests.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Shahzad, M.K., Zhang, Y., Raza, A. et al. Polymer Microfibers Incorporated with Silver Nanoparticles: a New Platform for Optical Sensing. Nanoscale Res Lett 14, 270 (2019).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:


  • Microfibers
  • Up-conversion luminescence
  • Er3+
  • Ag
  • Transmission losses
  • Sensitivity