## 4 Conclusions  
The development of a paper-based device towards a low-cost, printed point-of-need potentiostat has been presented that could contribute in a variety of applications. Some initial experimentation has shown that the opportunity exists to perform various electrochemistry experiments using the paper-based potentiostat, which would otherwise need to be performed in a laboratory using expensive, large and specialized equipment or using relatively expensive commercial handheld potentiostats. Although optimization is still required, the developed paper-based potentiostat delivers promising results, similar to those produced by a lab-based potentiostat.  
The paper-based potentiostat in Figure 6 consists of an inkjet-printed paper-based sensor port and an inkjet-printed paper-based USB port, of which the first connects to the sensor temporarily (so that various sensors can be used) and the second connects to an Arduino microprocessor, as illustrated in Figure 3. The aim is to integrate the Arduino on to paper in future and use the paper-based USB port to connect to a smart device (smartphone, laptop, desktop etc.). The paper-based potentiostat tracks and connections can be inkjet-printed using silver and dielectric ink (pin connections, insulation layers, and circuit tracks) and populated with off-the-shelf silicon chips.  
The miniaturized paper-based potentiostat in Figure 6 is low-cost, disposable and allows for point-of-need electrochemistry experiments. By utilizing ink-jet printing, it allows for the manufacturing to be fully automated in future. The miniaturized paper-based potentiostat is small enough to be stored in a wallet and is easy to transport and a costing analysis shows that the paper-based potentiostat costs significantly less than the price of the commercially available handheld potentiostat, even when taking manufacturing work costs into account. With continued development and mass manufacturing the cost will decrease further. This system will allow the user to perform electrochemical experiments on-site and have the option to either dispose of or reuse this portable, disposable and low-cost solution. In the case that data is only required to be stored and later analyzed, a laptop USB port is sufficient to power the device, as well as various portable power sources such as coin cells, off-the-shelf AA batteries, or printed flexible batteries. Wireless communication of results is also a future possibility.  
The additive nature of manufacturing the potentiostat allows for the addition of other modules such as a card sized Arduino board, a display and a battery. Furthermore, by printing each module, full  
Figure 6: The packaged paper-based potentiostat including a custom-made paper-based sensor connected via paper-connections (Reprinted with permission from the Proceedings of the 13 th Edition of IEEE AFRICON 2017, Copyright © 2018 IEEE [7]).  
manufacturing automation can be realized in future. Parts of the system would remain customizable depending on the application. Furthermore, the design used for the prototype PCB potentiostat front-end was used directly to manufacture an inkjet-printed circuit, illustrating the ease of technology integration and support of rapid prototyping. Inkjet-printing enables conformal electronics creating the possibility to apply this technology for various scenarios. Likewise, the versatility of potentiostats allow the investigation of various analytes using the paper-based potentiostat. The next steps include testing a hybrid paper-based low-cost potentiostat for environmental monitoring applications.