ImmunoTouch is a self-contained, portable ELISA system composed of a handheld electronic reader and sample assay card. A sample (e.g. blood, milk or diluent) is applied to the card via a sampling strip. The ImmunoTouch card contains various reagents required for a specific ELISA procedure. Once the card is inserted into the reader the test begins.

The prototype system focuses on Fasciola hepatica infection as a model disease to assess the ImmunoTouch technology in field use. The instrument and associated technology has also been tested with other animal parasite diseases such as Ostertagia ostertagi (stomach worm).

ImmunoTouch reduces time to result from approximately five days for a standard laboratory test (this includes acquiring sample, delivery to laboratory, testing and analysis of results) to 15 – 20 minutes for an on-site test.

Rapid test results allow the user to take prompt action against disease thus reducing the risk and limiting the spread of infection, which can have a major impact on both productivity and cost.

Reagent System

The ImmunoTouch system consists of four sealed cavities to store micro-litre volumes of ELISA reagents. The tear-drop design of the reagent cavity allows hydraulic focusing of solution towards a pressure-sensitive valve. Actuation pins in the card reader force sample and reagents throughout a channel network to an immunoelectrode detector or reaction chamber.

Sampling

ImmunoTouch utilises a removable strip technology with capillary flow fluidics for sample collection. The strip has a filtration function to remove cells and fat from a sample (if required). Once inserted into the card and the card placed in the electronic reader, the membrane touch actuation automatically seals itself and releases a metered volume to the immunoreactor or detector.

Electrode Design

ImmunoTouch detection methodology is based on charge measurement or coulometry for the detection and the sensitive quantitation of peroxidase labels in ELISAs.

The detector can operate with on-electrode capture molecules such as antibodies or antigens – immunoelectrode detector, or with off-electrode capture molecules – immunoreactors. The latter requires additional micro-fluidics integrated to the ImmunoTouch detector. In this case the detector effectively remains isolated from the ELISA reagent system.

Detection

The ImmunoTouch detector is a series of electrodes coated with antigens specific for the target antibody, e.g. cathepsin L1 (CL1) proteinase from liver fluke. The detector measures peroxidase levels in a thin-layer flow cell.

Fluidics

Pressure-sensitive cavities are housed within the ImmunoTouch card. Reagents move throughout the ImmunoTouch card via a series of microchannels to the detector through pin actuation from the reader.

ImmunoTouch offers a number of unique advantages:

• Rapid and quantitative measurements
• Simple single use disposable cards, cost effective
• On-site testing with results in 15 – 20 min
• Minimal end-user input required (sample in-result out)
• Multiplexing technology which could be expanded to detect a wide variety of diseases/parasites within a wide range of industrial sectors