**Author details**

78 Cellulose – Medical, Pharmaceutical and Electronic Applications

desirable this kind of implantable micro power sources.

electrodes.

**5. Conclusion** 

diagnosing and energy harvesting.

monolithic structure in which the separator and the electrodes are physically integrated into a thin and flexible polymeric structure. A highly porous structure is produced by electrospinning to work as a bio-battery after the deposition of metallic layers (electrodes) in each one of the faces (Figure 4). In order to power electronic medical implants, powersupply systems must be able to operate independently over a prolonged period of time, without the need of external recharging or refueling. This cellulose-based structure demonstrated the ability to generate electrical energy from physiological uids showing a power density of 3µW.cm-2 [54]. This is a really promising achievement since a typical power required for a pacemaker operation is around 1µW. Besides the supplying of low power consumption devices, biochemical monitoring systems and artificial human muscles stimulation mechanisms can also be foreseen as potential field of applications where it is

**Figure 4.** Schematic and macroscopic image of the bio-battery developed by our group. It consists in a cellulose acetate membrane, produced by electrospinning, covered with metallic layers to form the

The inspiring advances in the development of innovative cellulose-based bioelectronic devices and its promising perspectives make it a challenging field of study. Electronics can be made lightweight, flexible, and capable of intimate, non-invasive integration with the soft, curvilinear surfaces of biological tissues offering important opportunities for

Cellulose and its derivatives have demonstrated to be a versatile material with a unique chemical structure which provides a good platform for the construction of new biomaterials and biodevices. Indeed, the high density of free hydroxyl groups in the cellulose structure makes it a helpful solid substrate that can undergo functionalization allowing the production of new materials for novel advanced applications. From biological immobilization to energy storage devices, the progresses in cellulose functionalization are described as innovative and challenging. Future advances in cellulose-based devices can envisage the development of essential medical implantable devices and healthcare systems.

Ana Baptista, Isabel Ferreira and João Borges\* *CENIMAT/I3N and Materials Science Department, Faculty of Science and Technology of New University of Lisbon (FCT/UNL), Portugal* 
