Micro-structured interdigital capacitors with synthetic antibody receptors for ABO blood-group typing

- The striking part of designed setup is that sensor layer retains its recognition features even after an extended coating life time. Furthermore, the reversibility of the system could be improved by adequate washing and rinsing. As a whole, this sensing setup offers selective, straightforward and cost effective ABO blood group typing.
- Sensor system of general interest in health care.
- Innovative materials based on synthetic antibodies.
- Cost effective transducer and sensor coatings.
- Reversible sensor system.

Interdigital capacitors coated with surface imprinted polymer layers can be designed for ABO-blood group typing. Measurements with 10 mm IDCs in deionized water suggested a change in dielectric properties by erythrocyte adhesion which leads to increase in capacitance. In hypotonic conditions, reduction in resistance was monitored as the erythrocytes interacted with imprinted polymer layers, subsequently the cells burst and the ions were enriched near interdigital electrodes. A clear differentiation among all ABO-blood groups was achieved even for A-subgroups, with selectivity factor as high as four i.e. in case of blood group B typing. The basis of these findings are selective interactions between erythrocyte antigens with imprinted sensor coatings. Under isotonic conditions, inclusion of erythrocytes into cavities leads to increase in resistance, because of closed pores in the polymer layers hinder ion diffusion. An enhancement of this sensor signal was observed by a factor of 10 through using smaller IDCs electrode width i.e. 5 μm. Reversibility was improved by using different concentrations of sodium chloride for washing. Optimal frequency was found to be 10 kHz for the measurements to be done. Capacitive measurements confirmed that sensor layers can be reused even after 300 h of operation for blood group typing.

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