A Wearable Device Towards Automatic Detection and Treatment of Opioid Overdose

Abstract

Opioid-induced overdose is one of the leading causes of death among the US population under the age of 50. In 2021 alone, the death toll among opioid users rose to a devastating number of over 80,000. The overdose process can be reversed by the administration of naloxone, an opioid antagonist that rapidly counteracts the effects of opioid-induced respiratory depression. The idea of a closed-loop opioid overdose detection and naloxone delivery has emerged as a potential engineered solution to mitigate the deadly effects of the opioid epidemic. In this work, we introduce a wrist-worn wearable device that overcomes the portability issues of our previous work to create a closed-loop drug-delivery system, which includes (1) a Near-Infrared Spectroscopy (NIRS) sensor to detect a hypoxia-driven opioid overdose event, (2) a MOSFET switch, and (3) a Zero-Voltage Switching (ZVS) electromagnetic heater. Using brachial artery occlusion (BAO) with human subjects (n = 8), we demonstrated consistent low oxygenation events. Furthermore, we proved our device's capability to release the drug within 10 s after detecting a hypoxic event. We found that the changes in the oxyhemoglobin, deoxyhemoglobin and oxygenation saturation levels ( SpO₂) were different before and after the low-oxygenation events ( 0.001). Although additional human experiments are needed, our results to date point towards a potential tool in the battle to mitigate the effects of the opioid epidemic.

Fig. 1.

Electronic design of the drug delivery system. (a) Block diagram of the principal electronic elements of the NIRS sensor; (i) The 3.3 V supply from the voltage regulator; (ii) the ferrite bead and decoupling capacitor to stabilize the power supply signal; (iii) the photodiode from the SFH7050 and the power supply (lithium batteries); (iv) configuration of the TIA along with a low-pass filter to smooth the signal and; (v) the microcontroller of the system (SAMD21G18AU). (b) Block diagram of the Dual MOSFET trigger switch. (c) Block diagram of the ZVS electromagnetic field generator.

Fig. 2.

LED driver circuit with MOSFETS and resistors. (a) The power supply of 2 lithium batteries in series (7.4 V). (b) 3 LEDs of different colors for the NIRS approach. (c) Control signals handled by the microcontroller. (d) Representation of LEDs wavelengths penetration over the skin tissue to evaluate the changes in absorbance on the capillariess.

Fig. 3.

Block diagram of the components implemented for the benchtop experiments. (a) Schematic of the front side of the NIRS device. We activated a digital pin of the microcontroller to drive the switch and the ZVS module; (b) representation of the MOSFET switch driver to integrate the instrumentation circuit to the ZVS driver; (c) diagram of electromagnetic field generator, placed at different height levels to melt the PCM of our minimally invasive capsule.

Fig. 4.

Set up for the BAO trial mimicked with a conventional sphygmomanometer. Events during human trials: event (1): pre-occlusion section for a range of 60 seconds of resting time; event (2): low oxygen event due to BAO at 200 mmHg of pressure induced through the bracelet cuff; event (3): resting period after the BAO. The scale bar of this figure indicates 2 cm.

Fig. 5.

Design, fabrication, and testing of the NIRS wearable device. (a) SS heating element tube (b) HDPE tube and a PTFE sealing ball. (c) Final prototype of the drug reservoir sealed with PCM. (d) List of electronic components of the wearable device. (e) A fully assembled wearable device on a subject. (f) Evaluation of the wearable device to test the ZVS driver at different heights above the drug delivery capsule. (g) Time for the implantable drug delivery device to reach 42 °C at different distances. The scale bars for (a-c) is 1 mm; (d) is 1 cm; (e) is 5 mm; and (f) is 2 cm.

Fig. 6.

Human Experiments results and statistical analysis before, during and after the BAO trials. (a) Representative transient Infrared light intensity peak-peak values during a BAO experiment. (b) Infrared light intensity peak-peak values during the human trials: before, during and after the BAO events. (c) Representative transient red light intensity peak-peak values during a BAO experiment. (d) Red light intensity peak-peak values during the human trials: before, during and after the BAO events. (e) Representative transient $\Delta {HbO}_2$ concentration values during a BAO experiment. (f) $\Delta Hb{O}_2$ concentration values for pre-occlusion, during occlusion and after-occlusion. (g) Representative transient $\Delta \mathit{\text{HbR}}$ concentration values during a BAO experiment. (h) $\Delta \mathit{\text{HbR}}$ concentration values for pre-occlusion, during occlusion and after-occlusion. (i) Representative transient ${\mathit{\text{SpO}}}_2$ values during a BAO experiment. (j) ${\mathit{\text{SpO}}}_2$ levels during the human trials.

Fig. 7.

Noise induced by the wearable device within two frequency spectra and V_rms noise from the power supply. (a) Noise level between 30 kHz - 300 kHz. (b) Noise level between 300 kHz - 3 GHz. (c) V_rms noise of the power supply.