Platinum Thin Films Research Articles

The Role of Local Heating and Phosphate Poisoning during the Oxygen Reduction Reaction in Solid Acid Fuel Cells

With the ongoing effort to decarbonize and decentralize the electricity infrastructure by shifting to renewable energy sources, fuel cells and in particular intermediate temperature fuel cells receive a growing interest as a promising technology for a highly efficient, on demand transformation of chemical into electrical energy. Since the 2000s, fuel cells have cycled from high expectations to disillusion, caused by the high production cost an insufficient stability. High temperature polymer electrolyte membrane fuel cells (HT PEM FC) are a prominent and well investigated candidate for the intermediate temperature range. However, the usage of concentrated, highly corrosive phosphorous acid as membrane dopant required expensive production materials and causes deterioration of the catalyst over time. Changing from a liquid to a solid electrolyte can simultaneously improve the long term stability and reduce the construction price. A suitable solid acid is CsH2PO4. It is a non-toxic and less corrosive electrolyte with a proton conductivity of 2*10-2 S/cm at 240°C.[1] Since first demonstrated for fuel cell fabrication in 2003,[2] the platinum utilization and power densities have been improved ever since.[3,4] Solid acid fuel cells (SAFC) are already used in industry in a small scale, but the development has been hampered by the poor stability of the cathode electrode. The rate limiting reaction step is the complex oxygen reduction reaction (ORR) at the cathode side. During operation, it is the largest source of overpotential and hence waste heat generation.[5] For an active site, the current collector, electrolyte and gas phase need to be in direct contact with each other to provide all necessary reactants, thereby the interface resistance between the current collector and the catalyst is crucial for the performance.In the work we are going to present, we investigated electrodes based on a platinum thin film catalyst layer.[6,7] These electrodes enable us to investigate degradation effects on a reasonable time scale. We will show that only a few areas close to the current collectors meet the requirements for active sites and consequently generating most of the measured current, leading to a localized heating. We observed a current density depended morphology chance of CsH2PO4 during operation at these active sites, located close to the current collector. While a variety of degradation processes can result from this process, we determined a phosphate adsorption on the catalyst as the most pronounced one. Similar to HT PEM FC, phosphate species from the electrolyte can adsorb at the platinum surface and act as catalyst poison.[8–10] We will present, that these poisoning effects can be reversed but not prevented by cyclic voltammetry (CV) measurements. After reactivating the cell by CV measurements, the cell performance increased to the initial value before degrading again. The reversibility of the process was shown for five reactivations over a period of 50 h. Overall, we identified the cause and nature of the main degradation mechanism in solid acid fuel cells with platinum thin film electrodes and will present different design optimizations for a stable, high performance fuel cell which arise from our findings.

Platinum metallization on silicon and silicates

Abstract

Compact analytical flow system for the simultaneous determination of l-lactic and l-malic in red wines

During the malolactic fermentation of red wines, l-malic acid is mainly converted to l-lactic acid. Both acids should be precisely measured during the entire process to guarantee the quality of the final wine, thus making real-time monitoring approaches of great importance in the winemaking industry. Traditional analytical methods based on laboratory procedures are currently applied and cannot be deployed on-site. In this work, we report on the design and development of a bi-parametric compact analytical flow system integrating two electrochemical biosensors that could be potentially applied in this scenario. The developed flow-system will allow for the first time the simultaneous measurement of both acids in real scenarios at the real-time and in remote way. Miniaturized thin-film platinum four-electrode chips are fabricated on silicon substrates by standard photolithographic techniques and further implemented in a polymeric fluidic structure. This includes a 15 µL flow cell together with the required fluidic channels for sample and reagent fluid management. The four-electrode chip includes counter and pseudo-reference electrodes together with two working electrodes. These are sequentially modified with electropolymerized polypyrrole membranes that entrap the specific receptors for selectively detecting both target analytes. The analytical performance of both biosensors is studied by chronoamperometry, showing a linear range from 5 × 10−6 to 1 × 10−4 M (LOD of 3.2 ± 0.3 × 10−6 M) and from 1 × 10−7 to 1 × 10−6 M (LOD of 6.7 ± 0.2 × 10−8 M) for the l-lactate and the l-malate, respectively. Both biosensors show long-term stability, retaining more than the 90% of their initial sensitivity after more than 30 days, this being a prerequisite for monitoring the whole process of the malolactic fermentation of the red wines (time between 20 and 40 days). The flow system performance is assessed with several wine samples collected during the malolactic fermentation process of three red wines, showing an excellent agreement with the results obtained with the standard method.

Surface engineering of Pt thin films by low energy heavy ion irradiation

A systematic study of nanostructuring of platinum (Pt) thin films of different thicknesses deposited on silicon substrates has been performed under the irradiation of low energy Kr+ ions. First, Pt thin films of various thicknesses (~2–6 nm) were grown on the Si substrates, which were subsequently irradiated with 100 keV Kr+ ions as a function of ion fluence. The resultant surface modifications after irradiation are studied by atomic force microscopy (AFM), which reveals that higher ion fluence and larger thickness of Pt thin films are more favorable for nanostructures formation. Surface growth features have been analysed using kinetic roughening of surfaces. Scaling components (roughness and growth components) reveals that the sputtering is the principal factor causing surface nanostructuring in platinum (Pt) thin films. For higher thicknesses ion beam induced adatoms diffusion is favoring the surface roughning. The mechanism of nanostructuring on different thicknesses of Pt films has been analyzed using Rutherford backscattering spectrometry (RBS) study and SRIM-TRIM calculations. For higher thickness of Pt film, irradiating projectile ions results in high energy deposition in the film. Thus, thickness-dependent sputtering yield and adatoms surface diffusions play an important role in nanostructuring of Pt thin films under ion irradiation.

Attenuation of pulsation and oscillation using a disk at mid-section of spiked blunt body

The two most important modes of flow instability are observed on a flat-faced cylinder fitted with a spike, namely, pulsation and oscillation. A new technique is proposed in this article to attenuate both pressure and aerothermal fluctuations over the cylinder by using a circular disk at the mid-length of the sharp-tipped spike, which splits the separation region in front of the cylinder. Shock tunnel experiments are carried out at a free stream Mach number of M∞ = 5.7 and a Reynolds number of RD = 0.5 × 106 (based on the cylinder diameter, D). Aeroheating is measured using platinum thin film sensors painted over the front face of the cylinder. It is shown that the flow pulsation can be totally mitigated for the ratio of spike length to diameter (L/D = 1.0) by using a disk of diameter d/D = 28% at the mid-section of the spike, and the oscillation flow is suppressed using the same disk diameter with L/D = 1.5. This phenomenon is well evident from the measured heat transfer and schlieren data. Besides, a similar analysis showed that the flow fluctuation over an aerospike mounted on a hemispherical blunt body can be diminished with the use of double-aerospike, which, in turn, decreases the heat flux peak in the proximity of the reattachment. This is an effective means of flow fluctuation mitigation and presents to be a good thermal protection for the fore body.

Optical properties of tungsten trioxide, palladium, and platinum thin films for functional nanostructures engineering.

In recent years, we have been witnessing the intensive development of optical gas sensors. Thin palladium and platinum films as well as tungsten trioxide films with palladium or platinum catalysts are widely used for hydrogen detection, and the optical constants of these materials are required for sensor development. We report the optical parameters retrieved from a set of ellipsometric and transmission spectra for electron-beam evaporated palladium, platinum, and tungsten trioxide films. The tungsten trioxide films were 81 nm, 162 nm, and 515 nm thick and the metal films were as thin as 5-7 nm. Ultrathin palladium and platinum films were shown to be successfully described by local and isotropic permittivity, which is quite different from known bulk values. However, this permittivity showed a strong dependence on adjacent materials, thus illustrating that the ultrathin metallic films can be considered composites characterized by effective permittivity. With the obtained refractive indices and permittivities, the optical spectra of fabricated WO3/Pd and WO3/Pt nanostructures incorporating 1D grating of Al2O3 were in an excellent agreement with the calculated ones without requiring any additional fitting procedures or inclusion of surface roughness layers in numerical models.

Microstructural Evolution and ORR Activity of Nanocolumnar Platinum Thin Films with Different Mass Loadings Grown by High Pressure Sputtering

Nanocolumnar platinum thin films (Pt-TFs) with different Pt mass loadings were grown by high pressure sputtering (HIPS) and investigated as oxygen reduction reaction (ORR) electrocatalysts for polymer electrolyte membrane fuel cell applications. Mass loading was controlled by changing the sputter deposition time. A cauliflower-like columnar microstructure was achieved by depositing the Pt-TFs onto a microporous layer (MPL)-like surface composed of carbon particles in order to mimic catalyst-coated gas diffusion electrodes. Microstructural evolution of HIPS Pt-TFs and their ORR activity were investigated. Electrochemical characterization of the nanocolumnar Pt-TFs was performed by cyclic voltammetry and rotating disk electrode measurements on Pt-TF/MPL-like-layer/glassy-carbon samples in an aqueous perchloric acid electrolyte. The electrochemically active surface area increased from 18 to 39 m2 g−1 as the Pt mass loading was decreased. Specific activity of the films was similar (∼600 μA cm−2) for all Pt mass loadings, due to the similar nanoparticle sizes of ∼5 nm as observed by transmission electron microscopy and X-ray diffraction. Mass activity of the films increased from 0.11 to 0.26 A mg−1 as the Pt mass loading was decreased, which is an indication of the effective Pt utilization and better access through the catalyst layer at lower Pt mass loadings.

Shape Effect of Surface Defects on Nanohardness by Quasicontinuum Method.

Nanoindentation on a platinum thin film with surface defects in a rectangular shape and triangular shape was simulated using the quasicontinuum method to study the shape effect of surface defects on nanohardness. The results show that the nanohardness of thin film with triangular defects is basically larger than those with rectangular defects, which is closely related to the height of the surface defects at the boundary near to the indenter. Moreover, the triangular defect might have an enhancement effect on nanohardness by a certain size of the defects and the boundary orientation of the defect, where such an enhancement effect increases as the defect grows. Furthermore, the nanohardness decreases when the defect is folded from wide to narrow in the same atom cavity, and particularly expresses a more obvious drop when the height of the defects increases. In addition, larger sizes of the rectangular defect induce more reduction in nanohardness, while the nanohardness of the triangular surface defect is sensitive to the periodic arrangement of atoms changed by the boundary orientation of the defect, which is well explained and demonstrated by the calculation formula theory of necessary load for dislocation emission.

Mechanisms of Pulsed Laser-Induced Dewetting of Thin Platinum Films on Tantalum Substrates—A Quantitative Study

The mechanism of pulsed laser-induced dewetting (PLiD) of Pt thin films in the thickness range from 3.2 to 8.9 nm was investigated on smooth chemically polished Ta (PT) and patterned dimpled Ta (DT) substrates, both of which have a thin Ta2O5 layer on the surface. Complete dewetting was achieved for a film thickness of 3.2–4.6 nm. Beyond that, a distinct morphological evolution in the intermediate stages from bicontinuous to polygonal structures was observed with the change in thin-film thickness, enabling the determination of the transition thickness for Pt on Ta2O5/DT substrates to be between 5.9 and 7.7 nm. Furthermore, by examining the dependence of Pt nanoparticle (NP) size (D), nearest neighbor interparticle distance (L), and NP surface density (N) on the Pt film thickness (h), quantitative evidence was provided to demonstrate that PLiD of Pt thin films on Ta2O5/Ta substrates occurred via the spinodal dewetting mechanism. In particular, a power-law fit to the data obtained from Pt NPs on the Ta2O5/PT substrate showed that L has a quadratic dependence on h, that is, L = 5.13 h2.04. Also, the thickness dependence of D and N on Ta2O5/PT showed a power-law relationship of D = 3.74 h1.76 and N = 2.93 × 1012 h-4.03, respectively. These results are in excellent agreement with predictions from the spinodal dewetting theory. It has also been shown that the patterned DT surface underneath the Pt films exerted extra control on the NP morphology, causing a deviation from the power law as predicted by the spinodal dewetting mechanism. From the thickness dependence of L, D, and N, the Hamaker constant (A) of Pt, the proportional constant (a) correlating the characteristic spinodal length scale (Λ) and L, and the geometric factor (f (θ)) were determined.

M13 Bacteriophage-Assisted Morphological Engineering of Crack-Based Sensors for Highly Sensitive and Wide Linear Range Strain Sensing.

Despite their extraordinary mechanosensitivities, most channel-like crack-based strain sensors are limited by their poor levels of stretchability and linearity. This work presents a simple yet efficient way of modulating the cracking structure of thin metal films on elastomers to facilitate the development of high-performance wearable strain sensors. A net-shaped crack structure based on a thin platinum (Pt) film can be produced by coating an elastomer surface with M13 bacteriophages (phages) and consequently engineering the surface strain upon stretching. This process produces a Pt-on-phage (PoP) strain sensor that simultaneously exhibits high levels of stretchability (24%), sensitivity (maximum gauge factor ≈ 845.6 for 20-24%), and linearity (R2 ≈ 0.988 up to 20%). In addition, the sensor performance can be further modulated by either changing the phage coating volume or adding a silver nanowire coating to the PoP sensor film. The balanced strain-sensing performance, combined with fast response times and high levels of mechanical flexibility and operational stability, enables the devices to detect a wide range of human motions in real time after being attached to various body parts. Furthermore, PoP-based strain sensors can be usefully extended to detect more complex multidimensional strains through further strain engineering on a cross-patterned PoP film.

Polyimide-based Thin Film Conductors for High Frequency Data Transmission in Ultra- Conformable Implants

Abstract Application-specific integrated circuits (ASICs) embedded in polymers have been subject in implant manufacturing for the recent years. The increased functionality combined with good biocompatibility due to flexibility of thin implants makes them interesting for further studies. Thin-film ASICs can be used for the recording and processing of a high amount of biological signals, improving the performance of neural implants. Fabrication and analysis of gold and platinum thin-film connections are subject of this study, especially their capability as high frequency data transmission lines. Three layers of polyimide are used as flexible substrate and insulator of the traces. Various test structures were designed and fabricated, to investigate the resistance and reactance up to GHz frequencies, crosstalk and influence of vias between metallization layers. All conducting structures have a comparable design with a length of 50 mm and a metal thickness of 300 nm, while the line widths were varied. In this configuration gold and platinum thinfilm conductors are both suitable for high-frequency data transmission up to 100 MHz. This transmission frequency limit and impedances are unaffected by a wet environment and in accelerated aging tests. However, both metals show a high pass filter behavior, whose frequency behavior is mostly dependent by the self-inductance and resistance. A simplified ideal transmission model predicts the electrical behavior sufficiently and can be used to design the favored line impedance matching input impedances of the connected ASICs.

Transient heat transfer measurements on pulsating and oscillating flows in a shock tunnel

Flow field over high-speed vehicles can be changed drastically with the addition of a spike. These spiked bodies are associated with pulsation and oscillation unsteady flow phenomena on a spiked-body configuration. The flow separation leads to fluctuations in pressure and heat transfer of high amplitude and frequency. An investigation is made in this study, to measure the heat flux using platinum thin film sensors for these two unsteady flow characteristics, which would provide additional insights and may lead to better understanding of such type of flows. Experiments are carried out on a sharp-tipped spike attached to a flat face cylinder in a shock tunnel operating at Mach 5.7. Provisions are made to vary the spike length to diameter ratio (L/D), ranging from L/D = 0.75, 1, 1.25 and 1.5 for current investigation. The measured heat transfer varied from 100 W/cm2 to 10 W/cm2 for a pulsation case (L/D = 0.75) and whereas for the oscillation case (except for the corner gauges) the sensors indicate a heat transfer variation between 50 W/cm2 to 5 W/cm2. In additions, the corner gauge shows a heat transfer of around 120 W/cm2 to 10 W/cm2. This indicates the region of shock-shock interaction. The results from schlieren technique, used for visualization of the flow field is compliments the quantitative results.

Atomically Thin Film Platinum Supported Sub-Stoichiometric Titania: A Tunable Electrocatalyst for Fuel Cell Reactions

Designing efficient catalyst for fuel cell devices has gained an increasing amount of attention over the last decade for chemical to electrical energy conversion. The widespread commercialization of fuel cells, such as proton exchange membrane fuel cells, are hindered by the sluggish kinetics of the cathodic oxygen reduction reaction, the costly platinum catalyst employed within the cell, along with long-term catalyst degradation. One approach aimed at simultaneously addressing these drawbacks is to synthesize atomically thin film platinum on a robust support. While many catalysts are being investigated for fuel cell reactions, Pt based catalysts are in high demand due to stability, high activity, and low overpotential. We demonstrate an unprecedented electrochemical deposition of Pt on graphene/sub-stoichiometric titania supports (Ti2O3 and Ti3O5).Ti2O3 and Ti3O5 films were deposited on silicon wafers via pulsed laser deposition. Four-point probe measurements, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), ultraviolet photoelectron spectroscopy (UPS), and Scanning Electron Microscopy (SEM) were used to examine the chemical, electrical, and morphological properties of the sub-stoichiometric supports. Chemical vapor deposited graphene on copper foil was transferred through a series of etchants to produce the Gr/TixO2x-1 (x=1 or 2) support. Incorporating a graphene interfacial layer between Pt and TixO2x-1 served as a platform for large-area, fully wetted growth of two-dimensional Pt films. Pt thin films were electrochemically co-deposited on Gr/TixO2x-1 supports in an aqueous solution consisting of Pt2+ and Cu2+.The chemical and morphological properties of the electrochemically deposited Pt films were investigated using XPS and SEM, respectively. Pt films were found to exist in a metallic state. The functionality of the synthesized catalyst was tested using major fuel cell reactions including, oxygen reduction, methanol oxidation, and ammonia oxidation reactions. Overall, varying the stoichiometry of the TixO2x-1 supports leads to reaction overpotential tunability as predicted by fluctuations in the work-function of the support. This study provides insights on the preparation of a novel Pt/Gr/TixO2x-1 catalyst aimed at developing clean energy devices.

Fabrication of platinum thin films for ultra-high electrocatalytic hydrogen evolution reaction

While the noble metals (e.g., platinum, (Pt)) remain the benchmark electrocatalyst for the hydrogen evolution reaction (HER), their mass production require a reduced metal loading and faster fabrication protocols. The aim of the present work is to prepare Pt thin films by simple and fast fabrication technique, and to evaluate their performance for HER. The thin films of Pt are grown on two substrates, namely titanium foil (Ti) and nickel foam (NF), using a single step aerosol assisted chemical vapor deposition (AACVD) method. The film deposition time are varied from 20 to 60 min. Microscopic analyses suggest a gradual evolution of the films into percolated and/or porous nanostructures, a feature that remains highly desired to allow the maximum access of active sites. The performance of the as-prepared electrodes is evaluated by monitoring the HER in acidic electrolyte. The Pt film on nickel foam (Pt/NF) exhibits better electrical conductivity and smaller charge transfer resistance, while the film deposited on the Ti foil (Pt/Ti) demonstrates superior catalytic activity per active sites. The as-prepared Pt/Ti and Pt/NF electrodes produce 10 mA cm−2 at overpotential of 28 mV and 26 mV, respectively, better in performance than commercial Pt/C electrode (~39 mV), set a new bench mark electrocatalyst for the HER.

Investigations on sputter deposited lithium nickel manganese oxide thin film cathodes for micro battery applications

Abstract Lithium manganese oxide thin films have been deposited on nickel (Ni) and platinum (Pt) coated stainless steel substrates at room temperature using powder target by Radio Frequency (rf) reactive magnetron sputtering. The samples are exposed to heat treatment at 500 °C to form crystalline phase. Nickel and platinum thin film coatings have been carried out using direct current (DC) sputtering. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrochemical characterizations have been carried out. XPS spectra indicate the presence of all elements present in the powder target. A discharge capacity of 54 µAh µm−1 cm−2 and 48 µAh µm−1 cm−2 has been obtained from charge discharge studies in the potential range 2.0 to 4.4 V for the thin film samples deposited on Ni and Pt coated SS substrates correspondingly Charge discharge cycles are conducted up to 40 cycles.

Stable and Active Oxygen Reduction Catalysts with Reduced Noble Metal Loadings through Potential Triggered Support Passivation

AbstractThe development of stable, cost‐efficient and active materials is one of the main challenges in catalysis. The utilization of platinum in the electroreduction of oxygen is a salient example where the development of new material combinations has led to a drastic increase in specific activity compared to bare platinum. These material classes comprise nanostructured thin films, platinum alloys, shape‐controlled nanostructures and core–shell architectures. Excessive platinum substitution, however, leads to structural and catalytic instabilities. Herein, we introduce a catalyst concept that comprises the use of an atomically thin platinum film deposited on a potential‐triggered passivating support. The model catalyst exhibits an equal specific activity with higher atom utilization compared to bulk platinum. By using potential‐triggered passivation of titanium carbide, irregularities in the Pt film heal out via the formation of insoluble oxide species at the solid/liquid interface. The adaptation of the described catalyst design to the nanoscale and to high‐surface‐area structures highlight the potential for stable, passivating catalyst systems for various electrocatalytic reactions such as the oxygen reduction reaction.

Copper, gold, and platinum under femtosecond irradiation: Results of first-principles calculations

The paper investigates the interaction of femtosecond laser pulses with the thin films of copper, gold, and platinum. It considers electron-phonon relaxation processes and melting in the metal system nonequilibrium heated by laser radiation. Instead of the approximated formula by Wang et al. [Phys. Rev. B 50, 8016 (1994)], which is widely used to determine the temperature dependence of the electron-phonon coupling factor, we propose an improved approach for its more accurate calculation from first principles. Comparison with experiments and other calculations shows our approach to provide good calculation accuracy. Melting time versus absorbed energy density was estimated for the films and shown to be markedly sensitive to latent heat at low absorbed energy densities $(l1$ MJ/kg). Our calculations taken to study the temporal evolution of the (220) diffraction peak intensity after femtosecond irradiation show good agreement between experimental and theoretical data, which was attained due to higher accuracy in our determination of the temperature dependence electron-phonon coupling factor.

Effect of high temperature annealing on resistivity and temperature coefficient of resistance of sputtered platinum thin films of SiO2/Pt/SiOx interfaces

The influence of high temperature annealing up to 800∘C on electrical resistivity and temperature coefficient of resistance of magnetron sputtered platinum films were investigated experimentally and theoretically. Highly adherent platinum films were manufactured on silicon oxide interfaces without using additional adhesion layers like titanium or tantalum. Such platinum films can be extremely useful for the fabrication of microelectromechanical sensors. X-ray diffraction studies exhibit grain sizes in the range of 39 nm for the as-deposited case to 162 nm after annealing at 800 ∘C. Thereby film resistivity values decrease from 16.8 ± 0.4 µΩ cm to 12.7 ± 0.2 µΩ cm and temperature coefficient of resistance values increase from 2180 ppm/K to 2810 ppm/K. A good accordance to the model of Mayadas and Shatzkes for resistivity as well as Tellier and Tosser for temperature coefficient of resistance could be found. The reflection coefficient for electrons at grain boundaries is extracted for both models.

Highly textured Pt thin film grown at very low temperature using Ca2Nb3O10 nanosheets as seed layer

The decrease of the growth temperature of platinum (Pt) thin film on silicon substrate was studied using Ca2Nb3O10 nanosheets (CNOns) as seed layer. These nanosheets were obtained by the delamination of the layered perovskite KCa2Nb3O10 and they were deposited on silicon substrates by the Langmuir–Blodgett method. Pt thin films were sputtered on silicon coated by CNOns (CNOns/SiO2/Si), and on TiO2/SiO2/Si substrates for comparison, at temperatures ranging from room temperature up to 625 °C. X-ray diffraction, scanning electron microscopy, and atomic force microscopy were used to characterize the crystalline quality, thickness, surface morphology and roughness of the Pt thin films. Highly (111) textured Pt thin films were obtained on CNOns/SiO2/Si at substrate temperature as low as 200 °C. The full width at half maximum of the rocking curve of the (111) X-ray peak was about one degree, indicating a high crystalline orientation. The resistivity was measured at room temperature by the four point probes method to confirm the quality of Pt thin films elaborated at low temperatures. These results pave the way for easier integration of highly textured platinum thin film in low temperature microelectronic processes.

A Multi-Channel System for Temperature Sensing of Neural Stem Cells in Adherent Culture.

Neural stem cells (NSCs) can gradually proliferate or differentiate during adherent culture. It is found that stem cells have different temperature characteristics in different physiological states. In order to detect the temperature of NSCs during adherent culture, in this study, we have designed a temperature monitoring system, in which a thin-film platinum resistor was used as the sensor. The NSCs were seeded on the sensor, and the data acquisition device was connected to the host computer via Bluetooth. Results indicate that there are about 5000 cells attached on the surface of each sensor, and the cell viability is maintained at about 90% after 24 h culture. An electrostatic force microscope (EFM) result proves that there is no electric field on the sensor surface to influence the activity of NSCs. This system can work continuously for more than 24 h with 0.05 °C detection sensitivity. Furthermore, the significant temperature change of NSCs is observed when stimulated by different concentrations of thyroid hormone, which demonstrates that the temperature change related to cell activity. Therefore, by detecting the temperature of the cell population, the fabricated system can provide reference information for studying the metabolic state of NSCs, as well as physiological responses of cells under various conditions in biomedical applications.