23: A portable and modular readout solution for electrochemical measurements

Fejzo, Aldo; Stergiou, Ionnias; Orawez, Georg; Markocic, Miha; Cattaneo, Stefano

  1. CSEM, Regional Center Landquart, Landquart, Switzerland

The need for fully integrated and automated diagnostics solutions for human health is increasing, fueled by the widespread tendency of the industry to offer portable approaches enabled by the latest technological improvements in many medical sectors. CSEM has been working towards a highly versatile, easily customizable, and intuitively usable solution that allows non-invasive, point-of-care body fluid testing even for non-medically skilled users. Assays sensitive to pH, glucose and sodium have been developed and validated, with the possibility to expand measurements to several other biomarkers.

To circumvent the use of error prone measuring methods such as color-changing dipsticks, CSEM has developed electrochemical sensor solutions that directly acquire measurements through industry standard analog front-ends, leaving no space for human misinterpretation of the data. The now quantitative and digital measurements are accessible by the user through several means of communication for analysis and diagnosis. For example, with a Bluetooth connection and a smartphone application, the data analysis possibilities are highly improved with respect to what simple embedded processors can offer. This also allows to obtain a cost effective, rugged, and low-to-no maintenance design of the electronics side, since the data visualization is detached from the measuring device, allowing a considerable degree of flexibility for the different possible use cases.

The modularity of the system derives from the stacking strategy used throughout the design phase. A main board, housing the microcontroller, memory, Bluetooth chip and battery, is acting like a central computer and a board-to-board connector allows this main board to communicate with other peripheral boards, including the analog front-end board that carries out the electrochemical measurements.

The electrochemical reader measures electrical signals generated by the analytes on a turnkey designed sensor array. It interfaces with a cartridge, the disposable part of the system, which houses the electrochemical sensor array. Within several development projects, CSEM refined the cartridge assembly design and has reached, following multiple revisions, a very promising stage of evolution for the electrochemical sensor itself, fabricated through low-cost printing and deposition techniques. The sensors show very good reproducibility and outstanding agreement with laboratory measurement instruments. In addition, the cartridge assembly allows calibration solutions, buffers, analytes and rinsing solutions to be applied sequentially on the sensor array. Currently, this is still done manually; A fluidic actuation board capable of automating all liquid handling procedures is now in development to improve the readout solution and eliminate one more possible source of error from the system.

The result is therefore a versatile, high-performance electro-chemical reader, pocket sized but just as capable as other commercially available but much more bulky and expensive solutions. This reader along with a microfluidic cartridge integrating a range of different sensor assays and coupled to a smartphone, allows users to perform automated electrochemical measurements far away from a laboratory and at a far lower cost and footprint. Future developments will focus further on miniaturizing and integrating the solution into everyday use items, making non-invasive electrochemical monitoring accessible in everyday life.