Single-use equipment already plays an integral role in many bioprocesses. For example, disposable bag systems serve for storage, transportation and mixing. Single-use bioreactors are increasing in capacity and complexity and come supplied with single-use coupling and sampling components. Disposable equipment also can handle formulation, filtration and filling.
Manufacturers gain obvious benefits in terms of cost, cleanliness, validation and speed, but these shouldn't come at the expense of process performance. Optimal processing demands non-invasive single-use sensors to monitor parameters such as flow, pressure, pH, dissolved oxygen, conductivity and turbidity. So, suppliers are working hard to develop and enhance measurement technologies.
"What we are seeing is that the more heavily regulated processes are moving to single-use technology as a means to improve process efficiency, flexibility and conserve resources. It is common to eliminate hours or even days of production downtime while process piping and equipment is cleaned, sanitized and validated between production runs or changes in formulation. The potential annual cost savings from no longer needing clean water treatment for steam cleaning or wastewater treatment for the residue from cleaning can also add up to thousands of dollars. So engineers and scientists that work with these processes are pressing for accurate and reliable single-use sensors," says Curt Pinnow, new product development manager at fluid-handling specialist Cole-Parmer, Vernon Hills, Ill. He adds that units for pressure, conductivity, temperature and flow are the most common disposable sensors.
"Some of this need is simply the desire to have 100% of the process be single-use. However, another need is to be able to make a complete process sub-assembly portable. An example would be a tangential flow filtration (TFF) assembly (Figure 1), or a depth filtration skid," he adds. Bioreactor monitoring and filter screening sub-assemblies also are seeing increasing demand.
"One feature of the movement to single-use systems is the desire of the end-user to have a completely closed/sealed system, with no intrusions that may possibly damage or contaminate the contained biofluid. This has led to the development of non-contact/non-invasive sensors to measure attributes such as dissolved oxygen. While I don't know if these sensors are classified as disposable, the intent and usage is the same," notes Pinnow.
So for marketing purposes, Cole-Parmer combines these non-invasive sensors with disposable sensors into a new product category that allows users to address traditional measurement in new and innovative ways.
"The takeaway here is that the sensor manufacturers have managed to develop the technology in products priced so that they are truly single-use," he concludes.
"The interest in single-use/disposable systems has really taken off within the last ten years. In a nutshell, the cleaning/validation cycle of traditional stainless steel equipment takes time and requires a lot of high-cost, hard-plumbed steel equipment, as well as pure water and steam generation with associated energy costs, and waste disposal. Single-use systems enable a quick turnaround, lower investment, and minimization of errors during this cycle," says Dennis Annarelli, technical manager of sensor-maker PendoTECH, Princeton, N.J.