# A Soft, Biocompatible Magnetic Field Enabled Wireless Surgical Lighting Patty for Neurosurgery
## 3 Results
A highly deformable lighting surgical device can fit into difficult, narrow, or uneven surgical fields (Figure 3a). It provides the types of lighting required for the procedure while preventing a physical obstruction to the surgical field. Such surgical lighting devices can be given a specific conformation prior to implantation into the surgical area to provide certain functions during surgery. These functions involve the support of tissue, expanding the surgical field, and projection of light in a specific direction. Figure 3a shows the device bent to a radius of curvature R = 3 mm. The finite element analysis (FEA) revealed that for R = 3 mm, the maximum effective strain in copper traces is 0.1%, which is lower than its fracture strain (-5%) (Figure 3b) [14]. This suggests that surgical lighting  
Figure 2: Electrical characteristics of a surgical lighting party. **(a)** Circuit diagram of a surgical lighting party. Reed switch is denoted by S1. V\({}_{1}\) and V\({}_{2}\) represent a level of voltages at the NMOS2 gate and PMOS gate, respectively. V\({}_{3}\) indicates a level of voltage at the node. The value of capacitor and resistors are follows; C1 = 1 \(\mu\)F, R1 = 249 k\(\Omega\), R2 = 499 k\(\Omega\), and R3 = 10 k\(\Omega\). **(b)** A flowchart for device activation/deactivation by a magnet. **(c)** Plots of transient responses at V\({}_{1}\), V\({}_{2}\), and V\({}_{3}\) (S1), respectively. **(d)** Snapshot of a transient response at the NMOS2 gate node, V\({}_{1}\) at R4 = 10 k\(\Omega\) (left) and plot of threshold time for activation (LEDs on)/deactivation (LEDs off) as a function of resistance, R4 (right). **(e-l)** A series of circuit diagrams with voltages at nodes of interest labeled. devices can be applied to other organs systems, such as the human cochlea, men's endolymphatic canal, and adult brain (Figure 3c) [20; 21; 22]. Collectively, the deformability, memory, and size of LEDs make the device useful for narrow surgical corridors of corridors that naturally limit light, like the surgical abdomen viewed through a laparoscope. A set of batteries external to the surgical lighting device powers an electronic circuit including a control logic and LEDs. In this manner, the power supply can also be positioned outside of the surgical field during deployment of the lighting device. The encapsulated central lighting layer protects an electronic circuit, including a reed switch and logic circuits, from fluids and therefore ensures robust operation in a surgical field while managing fluids in the field (Figure 4a) (Video S2). The light intensity of a surgical lighting device is monitored when immersed in a fluid as a function of distance between a magnet and a device (Figure 4b) and time (Figure 4c). Unstable device operation or activation/deactivation by accident is associated with environmental noises, and management of such issues is critical for robust operation. Magnetic field intensity is inversely proportional to square distance, and its strength significantly reduces as it moves away from a source [23; 24]. This ensures robust operation in a manner that offers nearly complete insensitivity to surroundings provided limiting access of a magnet or environmental noise sources that may trigger the device at most 8 cm away from the device (Figure 4d). Figure 4e,f shows measurement setups. Here, we place a light sensor under a chunk of salmon and measure light intensity. For measurements of existing light instruments, we measured light intensity as a function of distance, ranging from 5 to 15 cm, between the surface of salmon and the lighting device. Since a surgeon's field of vision must be secured, we did not measure below 5 cm. Measurement results revealed that the wireless surgical lighting patty provides higher light intensity than existing light instruments do (Figure 4g). Understanding thermal characteristics of the lighting device is important since it may cause tissue damage by heating [25]. We assessed the thermal characteristics of the surgical lighting patty using an embedded temperature sensor.