A protein-engineered triblock copolymer hydrogel composed of two self-assembling domains (SADs) has been fabricated by a photoactivatable diazirine group followed by ultraviolet (UV)-mediated crosslinking. The photocrosslinkable protein polymer CEC-D has been patterned into various features including different micrometer-scale stripes by using lithographic techniques. The patterned hydrogels are important for encapsulation of small molecules where a photopatterned fraction of 50% is optimal for maximum absorption. Stripe-patterned CEC-D100–100 exhibits slightly lower swelling ratios, an 8.9 times lower erosion profile, and a 2.6-fold higher drug release compared to the unpatterned hydrogel control, CEC-D0. Our studies demonstrate the potential of photocrosslinkable protein polymer hydrogels to be used as scaffolds for therapeutic delivery of small molecules. Through photolithographic techniques on the protein hydrogel, a variety of functionalities can be achieved by patterning different features enabling the mimicry of biological systems.

We demonstrate a method for simultaneously measuring the back-scattering patterns and images of single laser-trapped airborne aerosol particles. This arrangement allows us to observe how the backscattering patterns change with particle size, shape, surface roughness, orientation, etc. The recoded scattering patterns cover the angular ranges of =167.7∘−180∘ including at 180∘exactly and =0∘−360∘ in spherical coordinates. The patterns show that the width of the average speckle intensity islands or rings is inversely proportional to particle size and how the shape of these intensity rings or islands also depends on the surface roughness. For an irregularly shaped particle with substantial roughness, the back-scattering patterns are formed with speckle intensity islands, the size and orientations of these islands depend more on the overall particle size and orientation, but have less relevance to the fine alteration of the surface structure and shapes. The back-scattering intensity at 180° is very sensitive to the particle parameters. It can change from a maximum to a minimum with a change of 0.1% in particle size or refractive index. The method has potential use in characterizing airborne aerosol particles, and may be used to provide back-scattering information for LIDAR applications.

Mercury cadmium telluride (HgCdTe) processing must be performed at a low temperature in order to reduce Hg depletion. To meet demand, low-temperature plasma enhanced atomic layer deposition (PE-ALD) is an emerging deposition technology for highly conformal thin films. We comparatively studied the effectiveness of low-temperature PE-ALD by measuring the ALD film roughness, thickness, and dielectric values. Conformal deposition was investigated through scanning electron microscopy images of the Al 2 O 3 film deposited onto high aspect ratio features dry-etched into HgCdTe. PE-ALD demonstrated conformal coatings of trenches, pillars and holes in advanced HgCdTe infrared sensor architectures.

We are developing resonator-quantum well infrared photodetectors (R-QWIPs) for long-wavelength applications. Detector pixels with 25 μm pitch were hybridized to fan-out circuits for radiometric measurements. With a moderate doping of 0.5×10¹⁸ cm^-3, we achieved a quantum efficiency (QE) of 37% and conversion efficiency (CE) of 15% in a 1.3 μm thick active material and 35% QE and 21% CE in a 0.6 μm thick active material. Both detectors are cutoff at 10.5 μm with a 2 μm bandwidth. The temperature at which photocurrent equals dark current is about 65 K under F/2 optics. The thicker detector shows a large QE polarity asymmetry due to nonlinear potential drop in the QWIP material layers.

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