A 10 mm3 Inductive Coupling Radio for Syringe-Implantable Smart Sensor Nodes

We present a near-field radio system for a millimeter-scale wireless smart sensor node that is implantable through a 14-gauge syringe needle. The proposed system integrates a radio system on chip and a magnetic antenna on a glass substrate within a total dimension of 1 x 1 x 10 mm(3). We demonstrate energy-efficient active near-field wireless communication between the millimeter-scale sensor node and a base station device through an RF energy-absorbing tissue. The wireless transceiver, digital baseband controller, wakeup controller, on-chip baseband timer, sleep timer, and MBUS controller are all integrated on the SoC to form a millimeter-scale sensor node, together with a 1 x 8 mm(2) magnetic antenna fabricated with a 1.5-mu m-thickness gold on a 100 mu m-thickness glass substrate. An asymmetric link is established pairing the sensor antenna with a codesigned 11x11 cm(2) base station antenna to achieve a link distance of up to 50 cm for sensor transmission and 20 cm for sensor reception. The transmitter consumes a 43.5 mu W average power at 2 kb/s, while the receiver power consumption is 36 mu W with a -54 dBm sensitivity at 100 kb/s. When powered by a 1x2.2 mm(2) thin-film battery (2 mu Ah, 4.1 V), the designed system has a two week expected lifetime without battery recharging when the system wakes up and transmits and receives 16 b data every 10 min.