Disposable Sensors Pass Litmus Test

Single-use instruments gain increasing favor as capabilities expand.

By Seán Ottewell, Editor at Large

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Portyrailo and his colleagues have been working on a technique that does away with costly proprietary RFID memory chips and their analog inputs in favor of passive 13.56-MHz RFID tags. These operate as inductively coupled sensors with 16-bit resolution provided by a sensor reader. "We have developed RFID sensors for the measurements of several critical manufacturing parameters such as pH, solution conductivity, temperature and pressure," he notes.

In over 500 hours of laboratory tests, the sensors have proven extremely accurate, both individually and when tested in different combinations.

The development process received a major boost in late January with the announcement of a partnership with Avery Dennison, Pasadena, Calif., to commercialize the RFID sensor technology.

"The goal of our partnership is to point these wireless RFID sensors to a series of applications ranging from food and beverage, to packaging, pollution prevention and industrial. While the full specification sheets for desired sensors in these and other applications are surely quite diverse, there are several common key requirements that are unmet by existing available sensors. These requirements include (1) high selectivity of measurements of chemicals of interest in the presence of high levels of interferences, and (2) achieving this selectivity without costly investments into electronic nose systems that are expensive, being $4,000–$50,000," explains Potyrailo.

Finesse Solutions, San Jose, Calif., chose Interphex 2011 in March in New York City to give bioprocessing companies a close-up look at its new single-use SensorPak. Integrated with its SmartBags plug-and-play bioprocessing containers, the sensors reportedly provide accurate, drift-free, in-situ pH and dissolved oxygen (DO) measurements for at least 21 days.

The SmartBag SensorPak leverages the company's TruFluor pH and DO phase fluorometric technology in a compact pre-calibrated assembly. The combined pH and DO optical reader uses advanced optical components including a large area photodiode that minimizes photo-degradation of the active sensing elements.

"This product is optimized for accuracy, lifetime, and ease of use. We anticipate that the SensorPak will provide a complete solution for single-use seed train bio-processing applications, which are still in great need of reliable and trustworthy key process parameter measurements," notes Mark Selker, the firm's chief technology officer.

The company also has released its T700 upstream processing platform for single-use bioreactors ranging from 25 L to 2000 L in size. Each turnkey system comprises TruViu G3 hardware, TruBio software, and TruFluor/TruTorr single-use sensors. The T700 platform brings the benefits of Emerson Process Management's DeltaV reliability for cGMP applications in an affordable package, with easy scalability to multiple process trains using the DeltaV TruLogic Controller, claims Finesse.

"We have worked closely with our end users to define the requirements for the next-generation single-use bioreactor controller. Seamless integration of single-use sensors and sensor redundancy were two key challenges to resolve. Our T700 platform allows end users to seamlessly transition from traditional to fully redundant single-use sensors. This represents a major advance in the control of single-use bioreactors," says John Greenwood, manager of integration and automation.

Finesse also has launched the core module of its VirtualTransmitter for interfacing to TruFluor pH and DO single-use sensors. "As single-use sensors become the de facto standard in bioprocessing, end users will expect them to be perfectly integrated into both the hardware and software of the control platform. VirtualTransmitter and TruFluor blades represent the next-generation evolution of our single-use bioreactor control product line," states CEO Barbara Paldus.

Meanwhile, SciLog of Madison, Wis., a developer of single-use sensors to measure conductivity, pressure and temperature, now is incorporating its sensors into disposable purification platforms — for TFF, normal flow filtration and chromatography.

Such platforms typically consist of an integrated assembly of filter elements or columns, flexible tubing, plastic connectors and bags, segments of peristaltic pump tubing, as well as sensors. They are designed and pre-assembled for a specific purification process and a given maximum process volume. In the final configuration, all elements of the purification platform are pre-sterilized, assembled and operated as a closed system.

SciLog's latest offering is the SciPure 200 automated single-use TFF system. Designed to meet cGMP and 21 CFR Part 11 standards for data-collection and security as a standalone device, the system is ideal for product development, process development and biomanufacturing, claims the company. Users can create and execute discrete or batch operations for filling, concentration and filtration via a color HMI touch screen and pre-installed software. All wetted flow-path manifold components are considered single-use consumables.

SciLog hopes to launch a range of sensors to measure parameters other than conductivity, pressure and temperature later in the year.


Seán Ottewell is Chemical Processing's Editor at Large. You can e-mail him at sottewell@putman.net.


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