In our attempt to provide some cost estimates for the development of a biosensor for different applications, we found that such data is difficult to obtain in the open literature. However, we provide two examples.
In one instance, the Swedish Rescue Service wanted an "artificial dog nose" to help localize minefields and free other areas of land. (Incidentally, this is also a high priority for the United Nations. For example, the estimated cost to clear Angola of minefields is about $40 billion or SEK 400 billion). Biosensor Applications (1999) in Sweden intended to deliver a prototype in August 1999 that would have cost SEK 1.1 million (roughly $100,000). Field testing in a central military field in Sweden was planned and an actual application in Angola was also being considered.
In another instance, a multianalyte biosensor instrument was proposed for the Environmental Protection Agency (EPA) for detecting phenolic compounds and for pathogens (Schmidt, 1997). The intent was to reduce the analysis turn-around time—from approximately 19 days to 15 minutes—and to reduce the annual cost of environmental analyses in the United States by more than $20 million. Schmidt emphasizes that the major barrier to the development of a biosensor for environmental measurement is the diversity of the environmental market. Thus, no one analyte application is large enough to justify the development cost of a specific biosensor instrument. This points out the need for a disposable biosensor that is capable of being adapted to dozens of analytes. Schmidt proposed that he could develop the required biosensor in 6 to 7 months at a cost of approximately $70,000.
Sensitive detection and rapid screening systems are critically needed to detect environmental chemicals that exhibit estrogenic and androgenic agonist and antagonist activities. For example, the pesticide methoprene binds to retinoic acid (vitamin A) receptors and results in developmental abnormalities. Similarly, the phytochemical diethylstilbestrol and the pesticide DDT interact with estrogen receptors and have been implicated in developmental and reproductive disorders as well as hormone-dependent cancers. Also, dioxin or TCDD, a by-product of manufacturing processes using trichlorophenols, also has been implicated in developmental defects and in tumor formation. Another example is the organophosphate insectide methyl parathion that disrupts neuronal networks in the central and peripheral nervous systems, resulting acutely in tremor, seizures, coma, or death and chronically in behavior abnormalities or sustained neuropathy. Thus, inexpensive in-vitro assays for the detection of steriodiogenic activity in environmental chemicals in the Mississippi River basin has been proposed (University of Mississippi, 2000). An initial estimate of $250,000-300,000
was obtained for the development of this biosensor with the time period of 12 years (Vo-Dinh, 2000). Sometimes, the high cost of development includes the high overhead charges of a particular institution or organization.
However, there is a critical need for such biosensors since, as Wiseman et al. (1999) indicate, there is increasing public concern about the gender hazard caused by environmental and dietary phytoestrogens and xenoestro-gens. This leads to increased risk of damage to species ecowebs (Polis, 1988). An early assessment of risk is required for the developing ecological disruption that includes in vitro assays for compounds known as estrogen mimics (Lynch and Wiseman, 1988) and in vivo bioindicators. Furthermore, Wiseman et al. suggest another approach that involves analyzing the ecoweb breakdown in five or more species (ecotranslators).
In their review of environmental biosensors, Rogers and Gerlach (1996) indicate that the new instruments and methods being developed do exhibit promise for the continuous in situ monitoring of toxic compounds. These authors compared two different detection systems (an immunoassay kit and a biosensor system) for the monitoring of groundwater pump-and-treat systems. Their projections were derived from cost-per-sample versus initial investment cost. They estimated the cost per assay for the immunoassay kits ranged from $50 to $75, and the cost for the biosensor was $8. The biosensor cost was slightly offset by the start-up costs for the immunoassay kits, which were considerably cheaper: The start-up costs for the immunoassay kits and the biosensor system were $3000 and $20,000, respectively.
Bradley (1998) indicates that a new class of sensors for environmental monitoring of gases such as C02, S02, 03 and nitrogen oxide has been described by Dasgupta et al. (1998). This sensor is based on an amorphous Teflon polymer. A 20-^m-thick tube filled with liquid acts as a liquid-core optical fiber. This is highly permeable to various gases, including those of environmental interest. Dasgupta et al. indicate that in its simplest form the sensor can be fabricated for less than $100, and it can be used to monitor pollutant gases at ambient temperature. Finally, the response times are less than 1 sec because the design facilitates diffusion, which is often a hindrance in biosensor development and in analyzing analyte-receptor binding kinetics.
Georgia Institute of Technology (1999) in Atlanta, Georgia, has developed a biosensor that is apparently expected to improve food safety. It identifies and determines concentrations of multiple pathogens such as E. coli 0157:H7 and Salmonella. This biosensor can detect these pathogens in food products in less than 2 hours while in operation on a processing plant floor. Of course, its most important contribution is the considerable reduction in time required to assess the presence of contamination. The biosensor designed costs $1000 to $5000 and can detect cells at levels of 500 cells per ml. Current laboratory techniques cost around $12,000 to $20,000 and can only detect cell levels of
5000 cells per ml. In addition, the laboratory techniques take from 8 to 24 hours to yield results.
We now discuss the products for the clinical glucose market. Weetall (1996) indicates that this market is unique in that it is large enough to encourage stand-alone products. In other words, it does not have to provide a menu of tests, to be competitive. In 1996, Weetall indicated that the products for this market range from several cents for paper strips to around a few dollars for disposable electrodes used in commercially available electrochemical devices. Present-day costs include, for example, around $60-$70 for the device that produces reliable results from a small blood spot (which is less traumatic than having to prick and press your finger to get a reasonable size spot as with some less expensive devices). The strips that are used to get a quantitative result cost around a dollar.
Finally, as a last example, we discuss the development of a biosensor that closely mimics biological sensory functions (Downard, 1998). No costs were available, but it took 10 years and a team of 60 scientists and engineers to convert this ion-channel switch (ICS) biosensor from a concept to a practical device (Cornell, 1997). The advantage of this sensor is that it directly provides a functional test of the interaction between a potential drug and an artificial cell membrane. According to Cornell, changes in the ion flux across the membrane may be detected as a change in the membrane's electrical conductance. This author indicates that in essence they have designed a tethered membrane that permits one to quickly screen drugs of importance very efficiently.
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