IEEE Robotics & Automation Magazine - March 2021 - 91

he outbreak of COVID-19 has caused immeasurable loss to the world. The highly contagious
virus poses a challenging risk to public health,
especially medical doctors, who are in close
contact with patients. Thus, robots can help
reduce the risk of medical professionals conducting massive
testing with throat swabs. Soft robots, fabricated with
compliant materials, allow for low-cost development and
safe interaction with humans and show promising
potentiality in testing.
In this article, we developed a new soft robot for effectively collecting pharyngeal samples from the throat (see Figure 1).
The robotic prototype consists of a conical-shaped
Yoshimura origami as the tip collecting segment and a
tapered soft bending actuator as the base to generate
motions that mimic a medical doctor's operational movements. Optimized taper angles enhance the elongating and
twisting of the origami tip while bending stability is
enhanced by the base actuator's tapering shape. The soft
robotic swab can achieve rapid (11 s/test) and stable collection with a collecting area up to 218 mm2.
Through studying the robot's interaction with a 3D printed throat model, the collecting motion (amplitude and frequency) and the force output of the soft robotic swab were
similar to a sophisticated medical doctor. We validated the
soft robotic swab system with human volunteers and proved
its effectiveness. This study provides design insights into
creating disposable robotic samplers for an autonomous
throat testing system in response to a global epidemic, such
as COVID-19.
Background
In 2020, more than 90 million people were infected by
COVID-19. This new virus possesses the characteristics of
high mortality, infectiousness, and difficulty in detection.
Being able to perform rapid testing is essential to cutting
virus transmission. As recommended by the World Health
Organization, nasopharyngeal swab collection is widely
applied for the detection of the virus [1]. Commonly, nurses and doctors stand face-to-face in front of the patients
and use a rigid, slim swab to scrape the patients' throats
and collect sputa (laryngeal epithelial cells) (see the third
section of the supplementary video). Nevertheless, this
approach leads to a high-intensity workload and exposes
medical workers to the risk of infection. Regarding this
risk, developing a robot to replace the medical doctors
would be of great benefit.
Existing laryngeal robots apply cotton swabs with rigid
sticks and then control the motion of the cotton swab through
a rigid robotic arm [2], [3]. There are two primary issues with
this rigid robotic approach: 1) the robotic arm mediates the
swab movement in front of the patient, and its overall movement causes discomfort [4]; and 2) involuntary movement of
the tongue may disturb the swab's motion, resulting in an offset of the collection position. Thus, developing a robotic system that can reduce the patient's concern and efficiently

collect throat sputa by preventing the disturbance of the
tongue would be essential. Soft materials are flexible, low cost,
and safe when interacting with humans [5]-[11]. With these
advantages, soft robots have drawn profound interest in medical applications, and existing examples include soft actuators
for minimally invasive surgery [12], [13], drug delivery [14],
[15], and medical monitoring [16], [17]. These exciting features also provide promising cues for soft robots to be applied
to throat testing.
In this work, we developed a soft robotic swab capable of
bending, twisting, and elongating to improve patients'
comfort. Sampling through a rigid cotton swab relies on the
motion of the robotic arm. However, the robotic arm's movement near a human face can cause discomfort and panic
[3]. With a soft robotic swab that can be pneumatically
actuated to deform inside
the human mouth, the
robotic arm's movement
will no longer be requirExisting laryngeal robots
ed during the sampling
process. The soft robotapply cotton swabs with
ic swab consists of two
components. The first is a
rigid sticks and then
Yoshimura origami-based
soft collecting segment
control the motion of the
capable of elongating and
twisting. Yoshimura origacotton swab through a rigid
mi structures have been
proven to have excellent
robotic arm.
elongation properties [18],
[19], and we improved the
origami structure to couple the twisting motion to offer more friction for sampling. The
second component is a soft bending actuator capable of horizontal bending to mimic the left-right collecting motion of
a medical doctor as well as increase the working stability
under a vertical tongue force. Another feature of the soft
robotic swab is that the collecting segment and bending
Clinical Subject

Soft Robotic
Throat Swab

Robotic Arm

Camera

Figure 1. An overview of the soft robotic throat swab system
(scale bar = 5 cm).

MARCH 2021

IEEE ROBOTICS & AUTOMATION MAGAZINE

IEEE Robotics & Automation Magazine - March 2021

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