Optical microsensor for counting food substance particles in lab-on-a-chips

Integrated optical detection is considered to be an important operation in lab-on-a-chips. This paper presents an optical fiber-based micro-sensor that is capable of detecting food substance particles in a lab-on-a-chip. The system consists of a microcontroller and associated circuitry, a laser emitter, a laser receiver, fiber optic cables, a microfluidics chip, and the food substance samples to be tested. When the particles flow through the microfluidic channel in the chip, the receiver’s output voltage varies due to the particles blocking the passage of the laser ray. The changes in the collected signals are analyzed to count the number of particles. Experiments are conducted on several food substance samples including talcum powder, ground ginger, and soy sauce. The experimental results are presented and discussed.

Gaze behavior among experts and trainees during optic disc examination : does how we look affect what we see?

Purpose. The authors compared the visual gaze behaviors of glaucoma subspecialists with those of ophthalmology trainees during optic disc and retinal nerve fiber layer (RNFL) examination.

Methods. Seven glaucoma subspecialists and 23 ophthalmology trainees participated in the project. Participants were shown eight glaucomatous optic disc images with varied morphology. Eye movements during examination of the optic disc photographs were tracked. For each disc image, graders were asked to assign a presumptive diagnosis for probability of glaucoma. There was no time restriction.

Results. Overall, trainees spent more time looking at disc images than glaucoma subspecialists (21.3 [13.9–37.7] vs. 16.6 [12.7–19.7]) seconds; median [interquartile range (IQR)], respectively; P < 0.01) and had no systematic patterns of gaze behavior, and gaze behavior was unaltered by disc morphology or topographic cues of pathology. Experienced viewers demonstrated more systematic and ordered gaze behavior patterns and spent longer times observing areas with the greatest likelihood of pathology (superior and inferior poles of the optic nerve head and adjacent RNFL) compared with the trainees. For discs with focal pathology, the proportion of total time spent examining definite areas of pathology was 28.9% (22.4%–33.6%) for glaucoma subspecialists and 13.5% (12.2%–19.2%) for trainees (median [IQR]; P < 0.05). Furthermore, experts adapted their viewing habits according to disc morphology.

Conclusions. Glaucoma subspecialists adopt systematic gaze behavior when examining the optic nerve and RNFL, whereas trainees do not. It remains to be elucidated whether incorporating systematic viewing behavior of the optic disc and RNFL into teaching programs for trainees may expedite their acquisition of accurate and efficient glaucoma diagnosis skills.