Michael J. Delwiche

Biosensor for on-line measurement of bovine progesterone during milking

Reproductive management is a major financial concern of the dairy industry, with missed estrus detection a main cause of lost income. A biosensor was developed for on-line measurement of progesterone in bovine milk and detection of estrus. The biosensor used an enzyme immunoassay format for molecular recognition, which was developed to run in approximately eight minutes. The sensor was designed to operate on-line in a dairy parlor using microinjection pumps and valves for fluid transport, fiber optics and photodiodes for light measurement, and a control computer for sequencing. Calibration showed a dynamic response between 0.1 and 5 ng/ml progesterone in milk. The reusability of the test well was evaluated. Thiocyanate (0.5 M, pH 5.1) quickly regenerated the antibody surface while maintaining antibody activity for 15-20 cycles, but noise from the residual enzyme limited reusability.

Towards Q-PCR of pathogenic bacteria with improved electrochemical double-tagged genosensing detection.

A very sensitive assay for the rapid detection of pathogenic bacteria based on electrochemical genosensing has been designed. The assay was performed by the PCR specific amplification of the eaeA gene, related with the pathogenic activity of Escherichia coli O157:H7. The efficiency and selectivity of the selected primers were firstly studied by using standard Quantitative PCR (Q-PCR) based on TaqMan fluorescent strategy. The bacteria amplicon was detected by using two different electrochemical genosensing strategies, a highly selective biosensor based on a bulk-modified avidin biocomposite (Av-GEB) and a highly sensitive magneto sensor (m-GEC). The electrochemical detection was achieved in both cases by the enzyme marker HRP. The assay showed to be very sensitive, being able to detect 4.5 ng microl(-1) and 0.45 ng microl(-1) of the original bacterial genome after only 10 cycles of PCR amplification, when the first and the second strategies were used, respectively. Moreover, the electrochemical strategies for the detection of the amplicon showed to be more sensitive compared with Q-PCR strategies based on fluorescent labels such as TaqMan probes.

An Impact Force Response Fruit Firmness Sorter

ABSTRACT Asingle lane firmness sorting system was developed which conveyed fruit horizontally at a constant speed (76.7 cm/s) and caused them to impact on a rigid surface. Impact force characteristics (C2 = (peak force)/(time to peak force)^) were used to sort fruit into hard, firm and soft categories, at 5.1 fruit/s. Correlation coefficients between C2, penetrometer firmness, and eleasticity were 0.84 and 0.90 for fresh market peaches, and 0.78 and 0.81 for processing pears. Approximately 74% of the peaches were sorted into the correct firmness range.

Theory of Fruit Firmness Sorting by Impact Forces

ABSTRACT THE impact forces of fruit striking a rigid surface were considered as a means for nondestructive determination of firmness. Impact forces were simulated with a simple elasticity model. Shape characteristics were evaluated as firmness predictors for variations in elasticity, mass, radius of curvature, and contact speed. The time characteristic (peak force)/(time to peak force squared) was sensitive to elasticity and relatively insensitive to fruit size. Frequency characteristics in the range 250 to 340 Hz exhibited a threshold relationship with elasticity and moderate sensitivity to size. All characteristics were sensitive to the speed at contact. Performance of several filter circuits to sense the designated frequency components was simulated. A Chebyshev filter gave better response than a biquad filter.

Comparison of primers for the detection of Salmonella enterica serovars using real‐time PCR

Aims:  To evaluate the specificity and sensitivity of PCR primers for the detection of Salmonella enterica in a real‐time PCR assay using pure cultures.

MANOMETRIC BIOSENSOR FOR ON-LINE MEASUREMENT OF MILK UREA

Performance of a prototype sensor for on-line measurement of urea in milk during milking was evaluated. The sensor was based on a manometric assay of the carbon dioxide generated by the enzymatic hydrolysis of urea. Temperature compensation of the sensor was described briefly, and was shown to be effective. The calibration of the sensor was described and resulted in a standard calibration error of about 0.15 mM of urea. The standard error of the sensor in milk was shown to be about 0.25 mM (given a physiological range of about 2-7 mM in cow milk). The sensor was simple, inexpensive, suffered from no interferences in raw milk, and completed a measurement cycle in about 5 min (less than the time to milk a typical cow). A custom made sampling device, whereby milk was passively collected from the milk line under vacuum, was shown to collect an ample volume within 10 s to run a test with the sensor. No measurable bubbles or foam were introduced from the sampling mechanism so that the milk sampled was not diminished in density compared to samples taken by other methods.

Finite element analysis of particle and liquid flow through an ultraviolet reactor

A computational fluid dynamics program was used to simulate liquid flow through an ultraviolet (UV) reactor. Salt tracer tests were performed at different flow rates to validate results from the program. Temporal and spatial descriptions of particle trajectories from the flow model were used to quantify flow pathways through the UV reactor. Particle trajectory information was then used in a separate numerical program to estimate temporal distribution of particles exiting the domain during discrete time steps for the flow solution. From these data, the exit time for particles transported through the modeled flow domain were compared with experimental tracer results. At low flow rates, the simulation results were within 95% confidence intervals established from the experimental data. At higher flow rates, the simulation results tended to predict a shorter exit time for particles than that observed experimentally with salt tracer studies. The results of this research can be used to compare UV disinfection efficacy on low transmission liquids without the need for extensive experiments or construction of prototypes.

Control of individual microsprinklers and fault detection strategies

Based on yield variability in orchards, it is evident that many trees receive too much or too little water and fertilizer under uniform management. Optimizing water and nutrient management based on the demand of individual trees could result in improved yield and environmental quality. A microsprinkler sensor and control system was developed to provide spatially variable delivery of water and fertilizer, and a prototype was installed in a nectarine orchard. Fifty individually addressable microsprinkler nodes, one located at every tree, each contained control circuitry and a valve. A drip line controller stored the irrigation schedule and issued commands to each node. Pressure sensors connected to some of the nodes provided lateral line pressure feedback. The system was programmed to irrigate individual trees for specific durations or to apply a specific volume of water at each tree. Time scheduled irrigation demonstrated the ability to provide microsprinkler control at individual trees, but also showed variation in discharge because of pressure differences between laterals. Volume scheduled irrigation used water pressure feedback to control the volume applied by individual microsprinklers more precisely, and the average error in application volume was 3.7%. Fault detection was used to check for damaged drip lines and clogged or damaged emitters. A pressure monitoring routine automatically logged errors and turned off the microsprinklers when drip line breaks and perforations caused pressure loss. Emitter diagnosis routines correctly identified clogged and damaged microsprinkler emitters in 359 of 366 observations. Irrigation control at the individual tree level has many useful features and should be explored further to characterize fully the benefits or disadvantages for orchard management.

Wireless mesh network for irrigation control and sensing.

Variations in plant water and nutrient demand and environmental regulations to protect water quality provide significant justification for site-specific irrigation and fertigation systems. We have developed wireless valve controllers that self-assemble into a mesh network. Mesh networking means that controllers pass messages to extend the effective communication range without using high-power radios. Solar energy is collected with a 200 mW panel to operate each controller node without yearly battery replacement. Nine nodes were tested in a mesh network, and each properly responded to commands. Measurements of battery voltage, solar panel voltage, enclosure temperature, and external sensors were transmitted every 10 min. Irrigation schedules were stored locally on each node and executed automatically. Schedules for each node were unique, based on the needs of the particular area being irrigated. Internal clock drift was an average 6.3 s per day. Clock offset was removed using daily time stamps. One-hop transmission range using 916 MHz radios varied from 20.9 m with a whip antenna at ground level to 241.1 m with a dipole antenna at 3 m. Node commands were acknowledged after an average of 2.7 s per hop. Charge consumption was approximately 7.03 mA·h per day for the node circuit and 1 mA·h per day for battery self-discharge. The solar panel produced 26.0 to 81.3 mA·h in direct sunlight and 6.5 to 13.7 mA·h in shade. Node operation is expected to be continuous with occasional sunlight exposure. Soil moisture, pressure, temperature, and other environmental sensors will be used for feedback control and detection of problems. Such a network of intelligent valve controllers will allow growers in orchards, vineyards, nurseries, greenhouses, and landscapes to develop management practices that improve water- and fertilizer-use efficiency.

Adaptation of a manometric biosensor to measure glucose and lactose

A manometric sensor previously developed to measure urea was modified to measure glucose and lactose through enzymatic oxidation. Change in pressure in an enclosed cavity was correlated to the depletion of oxygen resulting from the enzymatic oxidation of glucose or lactose. The response of the sensor was linear and could be made adjustable over a large range by adjusting the amount of sample loaded into the fixed volume reactor. Because of the slow mutarotation of glucose, the oxidation of glucose was not allowed to proceed to completion. Therefore, the precision of the sensor (approximately 0.2 mM in a range from 0 to 5 mM) was limited by variations in the oxidation rate of glucose by glucose oxidase. Because the assay for lactose measured glucose subsequent to the hydrolysis of lactose by beta-galactosidase, the same degree of precision was observed in lactose. Milk lactose, typically at concentrations of about 150 mM, was estimated using the lactose assay after first diluting the samples. For many fluids such as milk, the use of manometric sensors for oxidizable substrates may be preferable to optical and electrochemical methods because they are robust and suffer a low degree of optical and chemical interferences. Glucose and lactose are representative of many important oxidizable substrates, which may be determined in this manner, many of which do not suffer from limitations caused by mutarotation. In theory, detection limits less than 1 microM may be achieved using these methods.