By harnessing the power of synthetic biology, we aim to enhance the functionality of myoelectric prosthetics. Despite technological advancements in prosthetic limbs, the challenge remains in replicating the intricate function of the innate limb, emphasising the need for further innovation. A major limiting factor for these prosthetics is signal interference caused by the use of dry metal electrodes. These electrodes are negatively influenced by sweat and the dynamic nature of the skin, resulting in motion artefacts (Qu et al., 2024). These motion artefacts lead to the misinterpretation of electromyographic (EMG) signals and can cause the delayed or unintended movement of prosthesis. To improve the human-machine interface, we propose engineering Escherichia coli to produce the electrically conductive pili (E-pili) derived from Geobacter sulfurreducens. These protein filaments exhibit conductive properties comparable to inorganic materials, such as silicon or carbon nanotubes (Adhikari et al., 2016). By combining the pilin monomer with a protein binding peptide at its carboxyl terminus, we aim to create nanowires that specifically bind to proteins on the skin surface. In addition, to further improve E-pili conductivity and reduce motion artefacts, spider silk will be used as an insulator.
Throughout our studies, we have been introduced to various genetic disorders and illnesses that result in limb loss or limb differences requiring amputation. It was through these studies that we also learned about the current issues with existing prosthetics being a poor substitution for a lost limb. The main issue is that there is a lack of a direct connection between the electrodes and the skin, which leads to a loss of signal. As a result, we wondered if there was a way to harness synthetic biology to facilitate a direct connection between the prosthetic and the user to improve the signal. It was at this stage that we came across the concept of biological nanowires and began to research the idea of creating the electrodes themselves using synthetic biology, rather than just facilitating the binding alone. The team was fascinated not only by the ingenuity of this novel idea, but also by the notion that we could potentially solve a great number of issues in various implanted medical devices, and not just in prosthetics
Adhikari R.Y., Malvankar N.S., Tuominena M.T., & Lovley D.R. (2016). Conductivity of Individual Geobacter Pili. RSC Advances, 6, 8354-8357.
Qu, M., Lv, D., Zhou, J., Wang, Z., Zheng, Y., Zhang, G. & Xie, J. (2024). Sensing and Controlling Strategy for Upper Extremity Prosthetics Based on Piezoelectric Micromachined Ultrasound Transducer. IEEE Trans Biomed Eng, 71, 1161-1169.