Device design for global shutter operation in a 1.1-μm pixel image sensor and its application to near infrared sensing
Global shutter is a feature of some CMOS image sensors that allows capture of an entire image at a single point in time. We discuss how the device architecture of InVisage’s QuantumFilm enables global shutter operation by controlling the bias on the device stack without an additional transistor, giving high shutter efficiency in a 1.1 μm pixel CMOS image sensor. We use drift-diffusion device simulations to inform our design and reveal device and material properties that are key for carrier selectivity. Based on our device model, we fabricated global-shutter-enabled QuantumFilm devices for near infrared sensing applications and present a characterization of our devices.
Design and characterization of 1.1 micron pixel image sensor with high near infrared quantum efficiency
At the 940 nm wavelength, solar background irradiance is relatively low and device-mounted monochromatic LED emission can be used to illuminate and assess the shape, distance, and optical properties of objects. We report here NIR imaging that outperforms existing CMOS sensors by achieving record 42% quantum efficiency at 940 nm for a 1.1 μm pixel. The rationally engineered material properties of QuantumFilm allow tuning of the spectral response to the desired wavelength to achieve quantum efficiency that exceeds 40%. In addition, the combination of high QE with QuantumFilm’s distinctive film-based electronic global shutter mechanism allows for extremely low illumination power and therefore lowers time-averaged system power when imaging with active illumination.
Genotypic diversity in field isolates of Babesia bovis from cattle with babesiosis after vaccination.
OBJECTIVE
To determine whether particular genotypes of Babesia bovis were common to field isolates obtained from cattle properties in Queensland where the B bovis vaccine had apparently failed.


DESIGN
A comparative study of polymerase chain reaction genotypes in different populations of B bovis.


PROCEDURE
Two polymerase chain reaction assays were applied to analyse DNA extracts of B bovis vaccine (K, T and Dixie strains) and 27 field isolates from 24 properties where disease outbreaks had occurred despite the use of the vaccine. To evaluate the stability of the genotypes identified, 11 of the field isolates were inoculated into experimental cattle that had either been previously vaccinated with T strain or not vaccinated.


RESULTS
No particular genotype of B bovis was responsible for the problems observed in previously vaccinated herds. None of the isolates had genotypes identical to the vaccine strains used. No geographic trends among the genotypes were observed. Isolates that originated from the same property also had different genotypes. Blood passage of the 11 field isolates in either previously vaccinated or nonvaccinated cattle did not alter the original genotype.


CONCLUSION
No particular genotypes identified by the Bv80 and BvVA1 polymerase chain reaction assays could be associated with vaccine failures.