Hybrid GaSb/Si swept-wavelength laser sensor technology for next generation wearable healthcare device platform

Spectral region beyond 1.7 mu m is particularly interesting for biomedical spectroscopic sensing applications due to the presence of strong and molecule-specific ro-vibrational overtone and combination absorption bands for a number of important analytes such as glucose, lactate, urea, human serum albumin among others. However, this spectral region has been largely unexplored for applications targeting wearable device technology due to the absence of commercially available semiconductor light source technology. In this work we report on recent progress in developing beyond-state-of-the-art GaSb-based swept-wavelength laser technology as a key building-block of the proposed spectroscopic sensor concept. To demonstrate the capability of the technology, we provide experimental data of in vitro sensing concentrations down to the normal physiological range and beyond for glucose, lactates, urea and bovine serum albumin. Furthermore, we provide initial experimental evidence of non-invasive in vivo sensing experiment with extracted absorbance signature of human serum albumin collected from the wrist and demonstrate a clear path towards sensing other analytes. Finally, to demonstrate the full potential of the spectroscopic sensor technology for the wearable device market, we present results of our initial effort to realize a complete spectroscopic sensor system-on-a-chip based on hybrid GaSb/Si material platform and manufactured using conventional 200 mm silicon-on-insulator CMOS technology process in a commercial high-volume foundry

Thermal and Optical Properties of Red Luminescent Glass Forming Symmetric and Non Symmetric Styryl-4H-Pyran-4-Ylidene Fragment Containing Derivatives

Dyes with amorphous structure deposited from organic solvents and having good fluorescence properties show potential for photonic device applications. Organic glass-forming symmetric and non symmetric styryl- derivatives of 2(2,6-substituted-4H-pyran-4-ylidene)-malononitrile (it has backbone of known laser dye 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino)styryl]-4H-pyran), 2(2,6-substituted- 4H-pyran-4-ylidene)-1H-indene-1,3(2H)-dione and 2(2,6-substituted-4H-pyran-4-ylidene)-pyrimidine- 2,4,6(1H,3H,5H)-trione were synthesized and investigated. Glass transition temperatures higher than 110 C were achieved. The absorption bands in dichloromethane solution cover the spectral region from 450 nm to 600 nm with fluorescence maxima between 580 nm and 690 nm. Photoluminescence quantum yields of the compounds in solution are between 0.3 and 0.54, which is reduced by one order in thin amorphous film prepared from volatile organic solvents. Incorporation of bulky trityloxyethyl groups in the derivatives results in significant reduction of aggregate formation. Thus fluorescence concentration quenching is reduced, enabling higher doping levels as compared to the unsubstituted 4-(dicyanomethylene)- 2-methyl-6-[p-(dimethylamino)styryl]-4H-pyran dye

Orthogonal Solution-Processable Electron Transport Layers Based on Phenylpyridine Side-Chain Polystyrenes

This article reports the synthesis and characterization of a series of polystyrenes containing phenylpyridine moieties as side chains. Methanol solubility of these polymers is induced if the relative pyridine content of the overall aromatic units of the side chains is larger than 0.5. This allows for orthogonal processing of multilayered organic light emitting diode (OLED) stacks fabricated from solutions. The polymers show high thermal stability due to their glass-transition temperatures ranging from 136 up to 247 °C. High triplet energies of up to 2.8 eV are obtained by combination of the side-chain aromatic rings in the meta position. The use of the methanol soluble side-chain polymers as an electron transport layer (ETL) is demonstrated in an orthogonally processed three-layer green-emitting OLED stack. When depositing the ETL from methanol, redissolution of the underlying emission layer does not occur

Structure Properties Relationship of Donor–Acceptor Derivatives of Triphenylamine and 1,8-Naphthalimide

Solution-processable donor–acceptor molecules consisting of triphenylamine core and 1,8-naphthalimide arms were designed and synthesized by palladium-catalyzed Heck reaction. Dilute solutions of the synthesized compounds show strong absorption peaks in the visible wavelength range from 400 to 550 nm, which can be ascribed to the intramolecular charge transfer. Fluorescence quantum yields of dilute solutions of the synthesized materials range from 0.45 to 0.70, while those of the solid samples are in the range of 0.09–0.18. The synthesized molecules exhibit high thermal stability with the thermal degradation onset temperatures ranging from 431 to 448 °C. The compounds form glasses with glass-transition temperatures of 55–107 °C. DFT calculations show that HOMO and LUMO orbitals are almost entirely localized on the donor and acceptor moieties, respectively. Consequently, the frontier orbital energies for the three synthesized compounds are similar and practically do not depend on the number of 1,8-naphthalimide moieties. Ionization potentials of the solid samples (5.75–5.80 eV) are comparable. The charge-transporting properties of the synthesized materials were studied using xerographic time-of-flight method. Hole mobilities in the layers of the compounds having one and two 1,8-naphthalimide moieties exceed 10^–3 cm²·V^–1·s^–1 at high electric fields at room temperature. The differences on the hole mobilities between the three synthesized compounds are discussed in the frame of Marcus theory by comparing the reorganization energy and electronic coupling parameters