# A Soft, Biocompatible Magnetic Field Enabled Wireless Surgical Lighting Patty for Neurosurgery
## 4 Discussion  
Battery or near-field powered microcontroller chips could enable similar levels of functionalities, remote control of light delivery, or activation/deactivation of light sources. Their power requirement for wireless operation ranges from a few mA to tens of mA. It could be delivered by near-field couplings between a transmission coil and a receiver coil if the dimensions of a receiver coil are realistic, for example, 3 by 3 cm. Otherwise, power transmission efficiency significantly drops as the receiver coil is scaled down below 1 by 1 cm, similar to the minimum size of a surgical lighting patty [26]. Moreover, a battery (capacity of 10 mAh) powered microcontroller chip could last at most 1 h. On the other hand, an actuating mechanism enabled by a customized circuit, including a reed switch, allows for low power wireless operation (a few uA) in a manner that is impossible with near-field powered microcontroller chips (a few mA) [27]. Battery with the same capacity, 10 mAh, is enough to operate the customized circuit, up to 10 h. Existing lighted instruments, such as an endoscope, suction device, or bipolar forceps, with light sources attached at the tip could also achieve a similar level of functions. However, such lighted instruments can provide light with a narrow angle of view or only when they are applied to a surgical field. Their form factors also make them less ideal for applications in surgery that require deep dissection, such as brain surgery or lung cancer [28]. For example, aneurysm surgery requires deep dissection where access to targeted tissues or regions is allowed only through a narrow opening. Existing lighted instruments could access and deliver light through wide openings; however, we cannot avoid damage of nearby cells associated with removals of surrounding tissues. Similarly, surgery processes for a brain tumor or lung cancer could be facilitated by our surgical lighting patty. Photodynamic therapy (PDT) is a treatment that uses a photosensitizer and a particular type of light. When photosensitizers are exposed to a specific wavelength of light, they produce oxygen radicals  
Figure 4: Demonstration of a surgical lighting patty in a biofluidic environment and assessment of its characteristics. (**a**) Picture of an experimental setup for light intensity measurement. Here, a patty is immersed in saline solution. (**b**) Plot of light intensity of surgical lighting devices as a function of distance from the device. (**c**) Plot of light intensity of the device as a function of time. Here, a set of batteries up to three with a capacity of 11 mAh are connected in series. (**d**) Dynamic range of wireless operation. The results indicate the effective range at which a reed switch in the surgical lighting patty is activated by magnets. Threshold for an activation of a reed switch is 4 mT. Pictures of experimental setup for light intensity measurement of existing lighted instruments (**e**) and the surgical lighting device (S.L.D) (**f**). (**g**) Comparisons of light intensity with existing lighting instruments (E.L.I). (**h**) Thermal assessments of the surgical lighting patty. that kill nearby cells; in particular, tumor cells [29]. Here, continuous, uniform light delivery is critical for achieving high cure rates [30]. Access to tumor cells in the brain or organ systems is difficult, while skin tumors allow easy access to light. Our thin, miniaturized flexible surgical lighting patty can represent an attractive alternative. Lastly, alternative approaches described above except for suction devices cannot manage biofluids in a surgical field. Collectively, a hundred-folds reduction in power consumption, miniaturized dimensions, and multimodalities represent essential features of the wireless surgical lighting patty. The power supply can take a variety of forms. In some embodiments, the power supply can be integrated within or positioned along the light-emitting element.